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Re: [PATCH, PR43864] Gimple level duplicate block cleanup.
- From: Tom de Vries <vries at codesourcery dot com>
- To: Richard Guenther <richard dot guenther at gmail dot com>
- Cc: Steven Bosscher <stevenb dot gcc at gmail dot com>, gcc-patches at gcc dot gnu dot org
- Date: Sun, 17 Jul 2011 20:33:01 +0200
- Subject: Re: [PATCH, PR43864] Gimple level duplicate block cleanup.
- References: <4DEF4408.4040001@codesourcery.com> <BANLkTimAvGy1jRniWftbEvLnGwEN_0Ma8Q@mail.gmail.com> <4DF24C2C.7080808@codesourcery.com> <BANLkTi=rU-E3R8tSkN=iZWvZJ4DcTe-RCg@mail.gmail.com> <4E1C3A19.8060706@codesourcery.com> <CAFiYyc2VhgbAZ8U2iDMJqApzHR+GyCdOfskMEVvr5Mf2TwB8_A@mail.gmail.com>
On 07/12/2011 04:07 PM, Richard Guenther wrote:
> On Tue, Jul 12, 2011 at 2:12 PM, Tom de Vries <vries@codesourcery.com> wrote:
>> Hi Richard,
>>
>> here's a new version of the pass. I attempted to address as much as possible
>> your comments. The pass was bootstrapped and reg-tested on x86_64.
>>
>> On 06/14/2011 05:01 PM, Richard Guenther wrote:
>>> On Fri, Jun 10, 2011 at 6:54 PM, Tom de Vries <vries@codesourcery.com> wrote:
>>>> Hi Richard,
>>>>
>>>> thanks for the review.
>>>>
>>>> On 06/08/2011 11:55 AM, Richard Guenther wrote:
>>>>> On Wed, Jun 8, 2011 at 11:42 AM, Tom de Vries <vries@codesourcery.com> wrote:
>>>>>> Hi Richard,
>>>>>>
>>>>>> I have a patch for PR43864. The patch adds a gimple level duplicate block
>>>>>> cleanup. The patch has been bootstrapped and reg-tested on x86_64, and
>>>>>> reg-tested on ARM. The size impact on ARM for spec2000 is shown in the following
>>>>>> table (%, lower is better).
>>>>>>
>>>>>> none pic
>>>>>> thumb1 thumb2 thumb1 thumb2
>>>>>> spec2000 99.9 99.9 99.8 99.8
>>>>>>
>>>>>> PR43864 is currently marked as a duplicate of PR20070, but I'm not sure that the
>>>>>> optimizations proposed in PR20070 would fix this PR.
>>>>>>
>>>>>> The problem in this PR is that when compiling with -O2, the example below should
>>>>>> only have one call to free. The original problem is formulated in terms of -Os,
>>>>>> but currently we generate one call to free with -Os, although still not the
>>>>>> smallest code possible. I'll show here the -O2 case, since that's similar to the
>>>>>> original PR.
>>>>>>
>>>>
>>>> Example A. (naming it for reference below)
>>>>
>>>>>> #include <stdio.h>
>>>>>> void foo (char*, FILE*);
>>>>>> char* hprofStartupp(char *outputFileName, char *ctx)
>>>>>> {
>>>>>> char fileName[1000];
>>>>>> FILE *fp;
>>>>>> sprintf(fileName, outputFileName);
>>>>>> if (access(fileName, 1) == 0) {
>>>>>> free(ctx);
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> fp = fopen(fileName, 0);
>>>>>> if (fp == 0) {
>>>>>> free(ctx);
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> foo(outputFileName, fp);
>>>>>>
>>>>>> return ctx;
>>>>>> }
>>>>>>
>>>>>> AFAIU, there are 2 complementary methods of rtl optimizations proposed in PR20070.
>>>>>> - Merging 2 blocks which are identical expect for input registers, by using a
>>>>>> conditional move to choose between the different input registers.
>>>>>> - Merging 2 blocks which have different local registers, by ignoring those
>>>>>> differences
>>>>>>
>>>>>> Blocks .L6 and.L7 have no difference in local registers, but they have a
>>>>>> difference in input registers: r3 and r1. Replacing the move to r5 by a
>>>>>> conditional move would probably be benificial in terms of size, but it's not
>>>>>> clear what condition the conditional move should be using. Calculating such a
>>>>>> condition would add in size and increase the execution path.
>>>>>>
>>>>>> gcc -O2 -march=armv7-a -mthumb pr43864.c -S:
>>>>>> ...
>>>>>> push {r4, r5, lr}
>>>>>> mov r4, r0
>>>>>> sub sp, sp, #1004
>>>>>> mov r5, r1
>>>>>> mov r0, sp
>>>>>> mov r1, r4
>>>>>> bl sprintf
>>>>>> mov r0, sp
>>>>>> movs r1, #1
>>>>>> bl access
>>>>>> mov r3, r0
>>>>>> cbz r0, .L6
>>>>>> movs r1, #0
>>>>>> mov r0, sp
>>>>>> bl fopen
>>>>>> mov r1, r0
>>>>>> cbz r0, .L7
>>>>>> mov r0, r4
>>>>>> bl foo
>>>>>> .L3:
>>>>>> mov r0, r5
>>>>>> add sp, sp, #1004
>>>>>> pop {r4, r5, pc}
>>>>>> .L6:
>>>>>> mov r0, r5
>>>>>> mov r5, r3
>>>>>> bl free
>>>>>> b .L3
>>>>>> .L7:
>>>>>> mov r0, r5
>>>>>> mov r5, r1
>>>>>> bl free
>>>>>> b .L3
>>>>>> ...
>>>>>>
>>>>>> The proposed patch solved the problem by dealing with the 2 blocks at a level
>>>>>> when they are still identical: at gimple level. It detect that the 2 blocks are
>>>>>> identical, and removes one of them.
>>>>>>
>>>>>> The following table shows the impact of the patch on the example in terms of
>>>>>> size for -march=armv7-a:
>>>>>>
>>>>>> without with delta
>>>>>> Os : 108 104 -4
>>>>>> O2 : 120 104 -16
>>>>>> Os thumb: 68 64 -4
>>>>>> O2 thumb: 76 64 -12
>>>>>>
>>>>>> The gain in size for -O2 is that of removing the entire block, plus the
>>>>>> replacement of 2 moves by a constant set, which also decreases the execution
>>>>>> path. The patch ensures optimal code for both -O2 and -Os.
>>>>>>
>>>>>>
>>>>>> By keeping track of equivalent definitions in the 2 blocks, we can ignore those
>>>>>> differences in comparison. Without this feature, we would only match blocks with
>>>>>> resultless operations, due the the ssa-nature of gimples.
>>>>>> For example, with this feature, we reduce the following function to its minimum
>>>>>> at gimple level, rather than at rtl level.
>>>>>>
>>>>
>>>> Example B. (naming it for reference below)
>>>>
>>>>>> int f(int c, int b, int d)
>>>>>> {
>>>>>> int r, e;
>>>>>>
>>>>>> if (c)
>>>>>> r = b + d;
>>>>>> else
>>>>>> {
>>>>>> e = b + d;
>>>>>> r = e;
>>>>>> }
>>>>>>
>>>>>> return r;
>>>>>> }
>>>>>>
>>>>>> ;; Function f (f)
>>>>>>
>>>>>> f (int c, int b, int d)
>>>>>> {
>>>>>> int e;
>>>>>>
>>>>>> <bb 2>:
>>>>>> e_6 = b_3(D) + d_4(D);
>>>>>> return e_6;
>>>>>>
>>>>>> }
>>>>>>
>>>>>> I'll send the patch with the testcases in a separate email.
>>>>>>
>>>>>> OK for trunk?
>>>>>
>>>>> I don't like that you hook this into cleanup_tree_cfg - that is called
>>>>> _way_ too often.
>>>>>
>>>>
>>>> Here is a reworked patch that addresses several concerns, particularly the
>>>> compile time overhead.
>>>>
>>>> Changes:
>>>> - The optimization is now in a separate file.
>>>> - The optimization is now a pass rather than a cleanup. That allowed me to
>>>> remove the test for pass-local flags.
>>>> New is the pass driver tail_merge_optimize, based on
>>>> tree-cfgcleanup.c:cleanup_tree_cfg_1.
>>>> - The pass is run once, on SSA. Before, the patch would
>>>> fix example A only before SSA and example B only on SSA.
>>>> In order to fix example A on SSA, I added these changes:
>>>> - handle the vop state at entry of bb1 and bb2 as equal (gimple_equal_p)
>>>> - insert vop phi in bb2, and use that one (update_vuses)
>>>> - complete pt_solutions_equal_p.
>>>>
>>>> Passed x86_64 bootstrapping and regression testing, currently regtesting on ARM.
>>>>
>>>> I placed the pass at the earliest point where it fixes example B: After copy
>>>> propagation and dead code elimination, specifically, after the first invocation
>>>> of pass_cd_dce. Do you know (any other points) where the pass should be scheduled?
>>>
>>> It's probably reasonable to run it after IPA inlining has taken place which
>>> means insert it somewhen after the second pass_fre (I'd suggest after
>>> pass_merge_phi).
>>>
>>
>> I placed it there, but I ran into some interaction with
>> pass_late_warn_uninitialized. Addition of the pass makes test
>> gcc.dg/uninit-pred-2_c.c fail.
>>
>> FAIL: gcc.dg/uninit-pred-2_c.c bogus uninitialized var warning
>> (test for bogus messages, line 43)
>> FAIL: gcc.dg/uninit-pred-2_c.c real uninitialized var warning
>> (test for warnings, line 45)
>>
>> int foo_2 (int n, int m, int r)
>> {
>> int flag = 0;
>> int v;
>>
>> if (n)
>> {
>> v = r;
>> flag = 1;
>> }
>>
>> if (m) g++;
>> else bar ();
>>
>> if (flag)
>> blah (v); { dg-bogus "uninitialized" "bogus uninitialized var warning" }
>> else
>> blah (v); { dg-warning "uninitialized" "real uninitialized var warning" }
>>
>> return 0;
>> }
>>
>> The pass replaces the second call to blah with the first one, and eliminates
>> the if. After that, the uninitialized warning is issued for the line number
>> of the first call to blah, while at source level the warning only makes sense
>> for the second call to blah.
>>
>> Shall I try putting the pass after pass_late_warn_uninitialized?
>
> No, simply pass -fno-tree-tail-merge in the testcase.
>
>>> But my general comment still applies - I don't like the structural
>>> comparison code at all and you should really use the value-numbering
>>> machineries we have
>>
>> I now use sccvn.
>
> Good.
>
>>> or even better, merge this pass with FRE itself
>>> (or DOM if that suits you more). For FRE you'd want to hook into
>>> tree-ssa-pre.c:eliminate().
>>>
>>
>> If we need to do the transformation after pass_late_warn_uninitialized, it needs
>> to stay on its own, I suppose.
>
> I suppose part of the high cost of the pass is running SCCVN, so it
> makes sense to share that with the existing FRE run.
Done.
> Any reason
> you use VN_NOWALK?
>
No, that was just a first-try value.
>>>>> This also duplicates the literal matching done on the RTL level - instead
>>>>> I think this optimization would be more related to value-numbering
>>>>> (either that of SCCVN/FRE/PRE or that of DOM which also does
>>>>> jump-threading).
>>>>
>>>> The pass currently does just duplicate block elimination, not cross-jumping.
>>>> If we would like to extend this to cross-jumping, I think we need to do the
>>>> reverse of value numbering: walk backwards over the bb, and keep track of the
>>>> way values are used rather than defined. This will allows us to make a cut
>>>> halfway a basic block.
>>>
>>> I don't understand - I propose to do literal matching but using value-numbering
>>> for tracking equivalences to avoid literal matching for stuff we know is
>>> equivalent. In fact I think it will be mostly calls and stores where we
>>> need to do literal matching, but never intermediate computations on
>>> registers.
>>>
>>
>> I tried to implement that scheme now.
>>
>>> But maybe I miss something here.
>>>
>>>> In general, we cannot do cut halfway a basic block in the current implementation
>>>> (of value numbering and forward matching), since we assume equivalence of the
>>>> incoming vops at bb entry. This assumption is in general only valid if we indeed
>>>> replace the entire block by another entire block.
>>>
>>> Why are VOPs of concern at all?
>>>
>>
>> In the previous version, I inserted the phis for the vops manually.
>> In the current version of the pass, I let TODO_update_ssa_only_virtuals deal
>> with vops, so it's not relevant anymore.
>>
>>>> I imagine that a cross-jumping heuristic would be based on the length of the
>>>> match and the amount of non-vop phis it would introduce. Then value numbering
>>>> would be something orthogonal to this optimization, which would reduce amount of
>>>> phis needed for a cross-jump.
>>>> I think it would make sense to use SCCVN value numbering at the point that we
>>>> have this backward matching.
>>>>
>>>> I'm not sure whether it's a good idea to try to replace the current forward
>>>> local value numbering with SCCVN value numbering, since we currently declare
>>>> vops equal, which are, in the global sense, not equal. And once we go to
>>>> backward matching, we'll need something to keep track of the uses, and we can
>>>> reuse the current infrastructure for that, but not the SCCVN value numbering.
>>>>
>>>> Does that make any sense?
>>>
>>> Ok, let me think about this a bit.
>>>
>>
>> I tried to to be more clear on this in the header comment of the pass.
>>
>>> For now about the patch in general. The functions need renaming to
>>> something more sensible now that this isn't cfg-cleanup anymore.
>>>
>>> I miss a general overview of the pass - it's hard to reverse engineer
>>> its working for me.
>>
>> I added a header comment.
>>
>>> Like (working backwards), you are detecting
>>> duplicate predecessors
>>> - that obviously doesn't work for duplicates
>>> without any successors, like those ending in noreturn calls.
>>>
>>
>> Merging of blocks without successors works now.
>>
>>> + n = EDGE_COUNT (bb->preds);
>>> +
>>> + for (i = 0; i < n; ++i)
>>> + {
>>> + e1 = EDGE_PRED (bb, i);
>>> + if (e1->flags & EDGE_COMPLEX)
>>> + continue;
>>> + for (j = i + 1; j < n; ++j)
>>> + {
>>>
>>> that's quadratic in the number of predecessors.
>>>
>>
>> The quadratic comparison is now limited by PARAM_TAIL_MERGE_MAX_COMPARISONS.
>> Each bb is compared to maximally PARAM_TAIL_MERGE_MAX_COMPARISONS similar bbs
>> per worklist iteration.
>>
>>> + /* Block e1->src might be deleted. If bb and e1->src are the same
>>> + block, delete e2->src instead, by swapping e1 and e2. */
>>> + e1_swapped = (bb == e1->src) ? e2: e1;
>>> + e2_swapped = (bb == e1->src) ? e1: e2;
>>>
>>> is that because you incrementally merge preds two at a time? As you
>>> are deleting blocks don't you need to adjust the quadratic walking?
>>> Thus, with say four equivalent preds won't your code crash anyway?
>>>
>>
>> I think it was to make calculation of dominator info easier, but I use now
>> functions from dominance.c for that, so this piece of code is gone.
>>
>>> I think the code needs to delay the CFG manipulation to the end
>>> of this function.
>>>
>>
>> I now delay the cfg manipulation till after each analysis phase.
>>
>>> +/* Returns whether for all phis in E1->dest the phi alternatives for E1 and
>>> + E2 are either:
>>> + - equal, or
>>> + - defined locally in E1->src and E2->src.
>>> + In the latter case, register the alternatives in *PHI_EQUIV. */
>>> +
>>> +static bool
>>> +same_or_local_phi_alternatives (equiv_t *phi_equiv, edge e1, edge e2)
>>> +{
>>> + int n1 = e1->dest_idx;
>>> + int n2 = e2->dest_idx;
>>> + gimple_stmt_iterator gsi;
>>> + basic_block dest = e1->dest;
>>> + gcc_assert (dest == e2->dest);
>>>
>>> too many asserts in general - I'd say for this case pass in the destination
>>> block as argument.
>>>
>>> + gcc_assert (val1 != NULL_TREE);
>>> + gcc_assert (val2 != NULL_TREE);
>>>
>>> superfluous.
>>>
>>> +static bool
>>> +cleanup_duplicate_preds_1 (equiv_t phi_equiv, edge e1, edge e2)
>>> ...
>>> + VEC (edge,heap) *redirected_edges;
>>> + gcc_assert (bb == e2->dest);
>>>
>>> same.
>>>
>>> + if (e1->flags != e2->flags)
>>> + return false;
>>>
>>> that's bad - it should handle EDGE_TRUE/FALSE_VALUE mismatches
>>> by swapping edges in the preds.
>>>
>>
>> That's handled now.
>>
>>> + /* TODO: We could allow multiple successor edges here, as long as bb1 and bb2
>>> + have the same successors. */
>>> + if (EDGE_COUNT (bb1->succs) != 1 || EDGE_COUNT (bb2->succs) != 1)
>>> + return false;
>>>
>>> hm, ok - that would need fixing, too. Same or mergeable successors
>>> of course, which makes me wonder if doing this whole transformation
>>> incrementally and locally is a good idea ;) Also
>>>
>>
>> Also handled now.
>>
>>> + /* Calculate the changes to be made to the dominator info.
>>> + Calculate bb2_dom. */
>>> ...
>>>
>>> wouldn't be necessary I suppose (just throw away dom info after the
>>> pass).
>>>
>>> That is, I'd globally record BB equivalences (thus, "value-number"
>>> BBs) and apply the CFG manipulations at a single point.
>>>
>>
>> I delay the cfg manipulation till after each analysis phase. Delaying the cfg
>> manipulation till the end of the pass instead might make the analysis code more
>> convoluted.
>>
>>> Btw, I miss where you insert PHI nodes for all uses that flow in
>>> from the preds preds - you do that for VOPs but not for real
>>> operands?
>>>
>>
>> Indeed, inserting phis for non-vops is a todo.
>>
>>> + /* Replace uses of vuse2 with uses of the phi. */
>>> + for (gsi = gsi_start_bb (bb2); !gsi_end_p (gsi); gsi_next (&gsi))
>>> + {
>>>
>>> why not walk immediate uses of the old PHI and SET_USE to
>>> the new one instead (for those uses in the duplicate BB of course)?
>>>
>>
>> And I no longer insert VOP phis, but let a TODO handle that, so this code is gone.
>
> Ok. Somewhat costly in comparison though.
>
I tried to add that back, guarded by update_vops. Handled in update_vuses,
vop_phi, insn_vops, vop_at_entry, replace_block_by.
>>> + case GSS_CALL:
>>> + if (!pt_solution_equal_p (gimple_call_use_set (s1),
>>> + gimple_call_use_set (s2))
>>>
>>> I don't understand why you are concerned about equality of
>>> points-to information. Why not simply ior it (pt_solution_ior_into - note
>>> they are shared so you need to unshare them first).
>>>
>>
>> I let a todo handle the alias info now.
>
> Hmm, that's not going to work if it's needed for correctness.
>
Should be handed my merge_calls now.
>>> +/* Return true if p1 and p2 can be considered equal. */
>>> +
>>> +static bool
>>> +pt_solution_equal_p (struct pt_solution *p1, struct pt_solution *p2)
>>>
>>> would go into tree-ssa-structalias.c instead.
>>>
>>> +static bool
>>> +gimple_base_equal_p (gimple s1, gimple s2)
>>> +{
>>> ...
>>> + if (gimple_modified_p (s1) || gimple_modified_p (s2))
>>> + return false;
>>>
>>> that shouldn't be of concern.
>>>
>>> + if (s1->gsbase.subcode != s2->gsbase.subcode)
>>> + return false;
>>>
>>> for assigns that are of class GIMPLE_SINGLE_RHS we do not
>>> update subcode during transformations so it can differ for now
>>> equal statements.
>>>
>>
>> handled properly now.
>>
>>> I'm not sure if a splay tree for the SSA name version equivalency
>>> map is the best representation - I would have used a simple
>>> array of num_ssa_names size and assign value-numbers
>>> (the lesser version for example).
>>>
>>> Thus equiv_insert would do
>>>
>>> value = MIN (SSA_NAME_VERSION (val1), SSA_NAME_VERSION (val2));
>>> values[SSA_NAME_VERSION (val1)] = value;
>>> values[SSA_NAME_VERSION (val2)] = value;
>>>
>>> if the names are not defined in bb1 resp. bb2 we would have to insert
>>> a PHI node in the merged block - that would be a cost thingy for
>>> doing this value-numbering in a more global way.
>>>
>>
>> local value numbering code has been removed.
>>
>>> You don't seem to be concerned about the SSA names points-to
>>> information, but it surely has the same issues as that of the calls
>>> (so either they should be equal or they should be conservatively
>>> merged). But as-is you don't allow any values to flow into the
>>> merged blocks that are not equal for both edges, no?
>>>
>>
>> Correct, that's still a todo.
>>
>>> + TV_TREE_CFG, /* tv_id */
>>>
>>> add a new timevar. We wan to be able to turn the pass off,
>>> so also add a new option (I can see it might make debugging harder
>>> in some cases).
>>>
>>
>> I added -ftree-tail-merge and TV_TREE_TAIL_MERGE.
>>
>>> Can you assess the effect of the patch on GCC itself (for example
>>> when building cc1?)? What's the size benefit and the compile-time
>>> overhead?
>>>
>>
>> effect on building cc1:
>>
>> real user sys
>> without: 19m50.158s 19m 2.090s 0m20.860s
>> with: 19m59.456s 19m17.170s 0m20.350s
>> ----------
>> +15.080s
>> +1.31%
>
> That's quite a lot of time.
>
Measurement for this version:
real user sys
without 19m59.995s 19m 9.970s 0m21.050s
with 19m56.160s 19m14.830s 0m21.530s
----------
+4.86s
+0.42%
text data bss dec hex filename
17547657 41736 1364384 18953777 1213631 without/cc1
17211049 41736 1364384 18617169 11c1351 with/cc1
--------
-336608
-1.92%
>> $ size without/cc1 with/cc1
>> text data bss dec hex filename
>> 17515986 41320 1364352 18921658 120b8ba without/cc1
>> 17399226 41320 1364352 18804898 11ef0a2 with/cc1
>> --------
>> -116760
>> -0.67%
>>
>> OK for trunk, provided build & reg-testing on ARM is ok?
>
> I miss additions to the testsuite.
>
I will send an updated patch on thread
http://gcc.gnu.org/ml/gcc-patches/2011-06/msg00625.html.
>
> +static bool
> +bb_dominated_by_p (basic_block bb1, basic_block bb2)
>
> please use
>
> + if (TREE_CODE (val1) == SSA_NAME)
> + {
> + if (!same_preds
> && !SSA_NAME_IS_DEFAULT_DEF (val1)
> && !dominated_by_p (bb2, gimple_bb (SSA_NAME_DEF_STMT (val1)))
> return false;
>
> instead. All stmts should have a BB apart from def stmts of default defs
> (which are gimple_nops).
>
Done.
> +/* Return the canonical scc_vn tree for X, if we can use scc_vn_info.
> + Otherwise, return X. */
> +
> +static tree
> +gvn_val (tree x)
> +{
> + return ((scc_vn_ok && x != NULL && TREE_CODE (x) == SSA_NAME)
> + ? VN_INFO ((x))->valnum : x);
> +}
>
> I suppose we want to export vn_valueize from tree-ssa-sccvn.c instead
> which seems to perform the same.
Done.
> Do you ever call the above
> when scc_vn_ok is false or x is NULL?
Not in this version. Earlier, I also ran the pass if sccvn bailed out, but pre
and fre only run if sccvn succeeded.
>
> +static bool
> +gvn_uses_equal (tree val1, tree val2, basic_block bb1,
> + basic_block bb2, bool same_preds)
> +{
> + gimple def1, def2;
> + basic_block def1_bb, def2_bb;
> +
> + if (val1 == NULL_TREE || val2 == NULL_TREE)
> + return false;
>
> does this ever happen?
Not in the current version. Removed.
>
> + if (gvn_val (val1) != gvn_val (val2))
> + return false;
>
> I suppose a shortcut
>
> if (val1 == val2)
> return true;
>
> is possible?
>
Indeed. Added.
> +static int *bb_size;
> +
> +/* Init bb_size administration. */
> +
> +static void
> +init_bb_size (void)
> +{
>
> if you need more per-BB info you can hook it into bb->aux. What's the
> size used for (I guess I'll see below ...)?
>
> + for (gsi = gsi_start_nondebug_bb (bb);
> + !gsi_end_p (gsi); gsi_next_nondebug (&gsi))
> + size++;
>
> is pretty rough. I guess for a quick false result for comparing BBs
> (which means you could initialize the info lazily?)
Done.
>
> +struct same_succ
> +{
> + /* The bbs that have the same successor bbs. */
> + bitmap bbs;
> + /* The successor bbs. */
> + bitmap succs;
> + /* Indicates whether the EDGE_TRUE/FALSE_VALUEs of succ_flags are swapped for
> + bb. */
> + bitmap inverse;
> + /* The edge flags for each of the successor bbs. */
> + VEC (int, heap) *succ_flags;
> + /* Indicates whether the struct is in the worklist. */
> + bool in_worklist;
> +};
>
> looks somewhat odd at first sight - maybe a overall comment what this
> is used for is missing. Well, let's see.
>
Tried to add an overall comment.
> +static hashval_t
> +same_succ_hash (const void *ve)
> +{
> + const_same_succ_t e = (const_same_succ_t)ve;
> + hashval_t hashval = bitmap_hash (e->succs);
> + int flags;
> + unsigned int i;
> + unsigned int first = bitmap_first_set_bit (e->bbs);
> + int size = bb_size [first];
> + gimple_stmt_iterator gsi;
> + gimple stmt;
> + basic_block bb = BASIC_BLOCK (first);
> +
> + hashval = iterative_hash_hashval_t (size, hashval);
> + for (gsi = gsi_start_nondebug_bb (bb);
> + !gsi_end_p (gsi); gsi_next_nondebug (&gsi))
> + {
> + stmt = gsi_stmt (gsi);
> + hashval = iterative_hash_hashval_t (gimple_code (stmt), hashval);
> + if (!is_gimple_call (stmt))
> + continue;
> + if (gimple_call_internal_p (stmt))
> + hashval = iterative_hash_hashval_t
> + ((hashval_t) gimple_call_internal_fn (stmt), hashval);
> + else
> + hashval = iterative_hash_expr (gimple_call_fn (stmt), hashval);
>
> you could also keep a cache of the BB hash as you keep a cache
> of the size (if this function is called multiple times per BB).
Right, I forgot it's a closed hash table. Added the cache of the bb hash.
> The hash looks relatively weak - for all asignments it will hash
> in GIMPLE_ASSIGN only ... I'd at least hash in gimple_assign_rhs_code.
Done.
> The call handling OTOH looks overly complicated to me ;)
>
That's an attempt to handle compiling insn-recog.c efficiently. All bbs without
successors are grouped together, and even after selecting on same function name,
there are still thousands of bbs in that group. I added now the args as well.
> The hash will be dependent on stmt ordering even if that doesn't matter,
> like
>
> i = i + 1;
> j = j - 1;
>
> vs. the swapped variant.
Right, that's a todo, added that in the header comment.
> Similar the successor edges are not sorted,
> so true/false edges may be in different order.
>
I keep a cache of the successor edge flags, in order of bbs.
> Not sure yet if your comparison function would make those BBs
> unequal anyway.
>
> +static bool
> +inverse_flags (const_same_succ_t e1, const_same_succ_t e2)
> +{
> + int f1a, f1b, f2a, f2b;
> + int mask = ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
> +
> + if (VEC_length (int, e1->succ_flags) != 2)
> + return false;
> ...
>
> I wonder why you keep a VEC of successor edges in same_succ_t
> instead of using the embedded successor edge vector in the basic_block
> structure?
>
To keep the information in order of bbs, for quick comparison.
> + bb_to_same_succ[bb->index] = *slot;
>
> looks like a candidate for per-BB info in bb->aux, too.
>
Done.
> +static void
> +find_same_succ (void)
> +{
> + int i;
> + same_succ_t same = same_succ_alloc ();
> +
> + for (i = 0; i < last_basic_block; ++i)
> + {
> + find_same_succ_bb (BASIC_BLOCK (i), &same);
> + if (same == NULL)
> + same = same_succ_alloc ();
> + }
>
> I suppose you want FOR_EACH_BB (excluding entry/exit block) or
> FOR_ALL_BB (including them). The above also can
> have BASIC_BLOCK(i) == NULL. Similar in other places.
>
Done.
> + for (i = 0; i < n1; ++i)
> + {
> + ei = EDGE_PRED (bb1, i);
> + for (j = 0; j < n2; ++j)
> + {
> + ej = EDGE_PRED (bb2, j);
> + if (ei->src != ej->src)
> + continue;
> + nr_matches++;
> + break;
> + }
> + }
>
> FOR_EACH_EDGE (ei, iterator, bb1->preds)
> if (!find_edge (ei->src, bb2))
> return false;
>
> is easier to parse.
>
Done.
> +static bool
> +gimple_subcode_equal_p (gimple s1, gimple s2, bool inv_cond)
> +{
> + tree var, var_type;
> + bool honor_nans;
> +
> + if (is_gimple_assign (s1)
> + && gimple_assign_rhs_class (s1) == GIMPLE_SINGLE_RHS)
> + return true;
>
> the subcode for GIMPLE_SINGLE_RHS is gimple_assign_rhs_code
> (TREE_CODE of gimple_assign_rhs1 actually).
>
> +static bool
> +gimple_base_equal_p (gimple s1, gimple s2, bool inv_cond)
>
> I wonder if you still need this given ..
>
> +static bool
> +gimple_equal_p (gimple s1, gimple s2, bool same_preds, bool inv_cond)
> +{
> + unsigned int i;
> + enum gimple_statement_structure_enum gss;
> + tree lhs1, lhs2;
> + basic_block bb1 = gimple_bb (s1), bb2 = gimple_bb (s2);
> +
> + /* Handle omp gimples conservatively. */
> + if (is_gimple_omp (s1) || is_gimple_omp (s2))
> + return false;
> +
> + /* Handle lhs. */
> + lhs1 = gimple_get_lhs (s1);
> + lhs2 = gimple_get_lhs (s2);
> + if (lhs1 != NULL_TREE && lhs2 != NULL_TREE)
> + return (same_preds && TREE_CODE (lhs1) == SSA_NAME
> + && TREE_CODE (lhs2) == SSA_NAME
> + && gvn_val (lhs1) == gvn_val (lhs2));
> + else if (!(lhs1 == NULL_TREE && lhs2 == NULL_TREE))
> + return false;
>
> all lhs equivalency is defered to GVN (which means all GIMPLE_ASSIGN
> and GIMPLE_CALL stmts with a lhs).
>
> That leaves the case of calls without a lhs. I'd rather structure this
> function like
>
> if (gimple_code (s1) != gimple_code (s2))
> return false;
> swithc (gimple_code (s1))
> {
> case GIMPLE_CALL:
> ... compare arguments ...
> if equal ok, if not and we have a lhs use GVN.
>
> case GIMPLE_ASSIGN:
> ... compare GVN of the LHS ...
>
> case GIMPLE_COND:
> ... compare operands ...
>
> default:
> return false;
> }
>
>
Done.
> +static bool
> +bb_gimple_equal_p (basic_block bb1, basic_block bb2, bool same_preds,
> + bool inv_cond)
> +
> +{
>
> you don't do an early out by comparing the pre-computed sizes.
This function is only called for bb with the same size. The hash table equal
fuction does have the size comparison.
> Mind
> you can have hashtable collisions where they still differ (did you
> check hashtable stats on it? how is the collision rate?)
>
I managed to lower the collision rate by specifying n_basic_blocks as hash table
size.
While compiling insn-recog.c, the highest collision rate for a function is 2.69.
> +static bool
> +bb_has_non_vop_phi (basic_block bb)
> +{
> + gimple_seq phis = phi_nodes (bb);
> + gimple phi;
> +
> + if (phis == NULL)
> + return false;
> +
> + if (!gimple_seq_singleton_p (phis))
> + return true;
> +
> + phi = gimple_seq_first_stmt (phis);
> + return !VOID_TYPE_P (TREE_TYPE (gimple_phi_result (phi)));
>
> return is_gimple_reg (gimple_phi_result (phi));
>
Done.
> +static void
> +update_debug_stmts (void)
> +{
> + int i;
> + basic_block bb;
> +
> + for (i = 0; i < last_basic_block; ++i)
> + {
> + gimple stmt;
> + gimple_stmt_iterator gsi;
> +
> + bb = BASIC_BLOCK (i);
>
> FOR_EACH_BB
>
> it must be possible to avoid scanning basic-blocks that are not affected
> by the transform, no? In fact the only affected basic-blocks should be
> those that were merged with another block?
Done. I also check for MAY_HAVE_DEBUG_STMTS now.
>
> + /* Mark vops for updating. Without this, TODO_update_ssa_only_virtuals
> + won't do anything. */
> + mark_sym_for_renaming (gimple_vop (cfun));
>
> it won't insert any PHIs, that's correct. Still somewhat ugly, a manual
> update of PHI nodes should be possible.
>
Added. I'm trying to be lazy about it though:
+ bool update_vops = ((todo & TODO_update_ssa_only_virtuals) == 0
+ || !symbol_marked_for_renaming (gimple_vop (cfun)));
If we're going to insert those phis anyway given the current todo, we don't bother.
> + if (dump_file)
> + {
> + fprintf (dump_file, "Before TODOs.\n");
>
> with TDF_DETAILS only please.
>
Done.
> + free_dominance_info (CDI_DOMINATORS);
>
> if you keep dominance info up-to-date there is no need to free it.
>
Indeed. And by not freeing it, the info was checked, and I hit validation errors
in that info, so the updating code had problems. I reverted back to calculating
when needed and freeing when changed.
> + TODO_verify_ssa | TODO_verify_stmts
> + | TODO_verify_flow | TODO_update_ssa_only_virtuals
> + | TODO_rebuild_alias
>
> please no TODO_rebuild_alias, simply remove it - alias info in merged
> paths should be compatible enough if there is value-equivalence between
> SSA names. At least you can't rely on TODO_rebuild_alias for
> correctness - it is skipped if IPA PTA was run for example.
>
Done.
> + | TODO_cleanup_cfg
>
> is that needed? If so return it from your execute function if you changed
> anything only. But I doubt your transformation introduces cleanup
> opportunities?
>
If all the predeccessor blocks of a block are merged, the block and it's
remaining predecessor block might be merged, so that is a cleanup opportunity.
Removed for the moment.
> New options and params need documentation in doc/invoke.texi.
>
Added.
> Thanks,
> Richard.
>
Bootstrapped and reg-tested on x86_64. Ok for trunk (after ARM testing)?
Thanks,
- Tom
2011-07-17 Tom de Vries <tom@codesourcery.com>
PR middle-end/43864
* tree-ssa-tail-merge.c: New file.
(struct same_succ): Define.
(same_succ_t, const_same_succ_t): New typedef.
(struct bb_cluster): Define.
(bb_cluster_t, const_bb_cluster_t): New typedef.
(struct aux_bb_info): Define.
(BB_SIZE, BB_SAME_SUCC, BB_CLUSTER, BB_VOP_AT_EXIT): Define.
(gvn_uses_equal): New function.
(same_succ_print, same_succ_print_traverse, same_succ_hash)
(inverse_flags, same_succ_equal, same_succ_alloc, same_succ_delete)
(same_succ_reset): New function.
(same_succ_htab, same_succ_edge_flags)
(deleted_bbs, deleted_bb_preds): New var.
(debug_same_succ): New function.
(worklist): New var.
(print_worklist, add_to_worklist, find_same_succ_bb, find_same_succ)
(init_worklist, delete_worklist, delete_basic_block_same_succ)
(same_succ_flush_bbs, update_worklist): New function.
(print_cluster, debug_cluster, same_predecessors)
(add_bb_to_cluster, new_cluster, delete_cluster): New function.
(all_clusters): New var.
(alloc_cluster_vectors, reset_cluster_vectors, delete_cluster_vectors)
(merge_clusters, set_cluster): New function.
(gimple_equal_p, find_duplicate, same_phi_alternatives_1)
(same_phi_alternatives, bb_has_non_vop_phi, find_clusters_1)
(find_clusters): New function.
(merge_calls, update_vuses, vop_phi, insn_vops, vop_at_entry)
(replace_block_by): New function.
(update_bbs): New var.
(apply_clusters): New function.
(update_debug_stmt, update_debug_stmts): New function.
(tail_merge_optimize): New function.
tree-flow.h (tail_merge_optimize): Declare.
* tree-ssa-pre.c (execute_pre): Use tail_merge_optimize.
* Makefile.in (OBJS-common): Add tree-ssa-tail-merge.o.
(tree-ssa-tail-merge.o): New rule.
* opts.c (default_options_table): Set OPT_ftree_tail_merge by default at
OPT_LEVELS_2_PLUS.
* tree-ssa-sccvn.c (vn_valueize): Move to ...
* tree-ssa-sccvn.h (vn_valueize): Here.
* tree-ssa-alias.h (pt_solution_ior_into_shared): Declare.
* tree-ssa-structalias.c (find_what_var_points_to): Factor out and
use ...
(pt_solution_share): New function.
(pt_solution_unshare, pt_solution_ior_into_shared): New function.
(delete_points_to_sets): Nullify shared_bitmap_table after deletion.
* timevar.def (TV_TREE_TAIL_MERGE): New timevar.
* common.opt (ftree-tail-merge): New switch.
* params.def (PARAM_MAX_TAIL_MERGE_COMPARISONS): New parameter.
* doc/invoke.texi (Optimization Options, -O2): Add -ftree-tail-merge.
(-ftree-tail-merge, max-tail-merge-comparisons): New item.
Index: gcc/tree-ssa-tail-merge.c
===================================================================
--- gcc/tree-ssa-tail-merge.c (revision 0)
+++ gcc/tree-ssa-tail-merge.c (revision 0)
@@ -0,0 +1,1676 @@
+/* Tail merging for gimple.
+ Copyright (C) 2011 Free Software Foundation, Inc.
+ Contributed by Tom de Vries (tom@codesourcery.com)
+
+This file is part of GCC.
+
+GCC is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 3, or (at your option)
+any later version.
+
+GCC is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GCC; see the file COPYING3. If not see
+<http://www.gnu.org/licenses/>. */
+
+/* Pass overview.
+
+
+ MOTIVATIONAL EXAMPLE
+
+ gimple representation of gcc/testsuite/gcc.dg/pr43864.c at
+
+ hprofStartupp (charD.1 * outputFileNameD.2600, charD.1 * ctxD.2601)
+ {
+ struct FILED.1638 * fpD.2605;
+ charD.1 fileNameD.2604[1000];
+ intD.0 D.3915;
+ const charD.1 * restrict outputFileName.0D.3914;
+
+ # BLOCK 2 freq:10000
+ # PRED: ENTRY [100.0%] (fallthru,exec)
+ # PT = nonlocal { D.3926 } (restr)
+ outputFileName.0D.3914_3
+ = (const charD.1 * restrict) outputFileNameD.2600_2(D);
+ # .MEMD.3923_13 = VDEF <.MEMD.3923_12(D)>
+ # USE = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ # CLB = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ sprintfD.759 (&fileNameD.2604, outputFileName.0D.3914_3);
+ # .MEMD.3923_14 = VDEF <.MEMD.3923_13>
+ # USE = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ # CLB = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ D.3915_4 = accessD.2606 (&fileNameD.2604, 1);
+ if (D.3915_4 == 0)
+ goto <bb 3>;
+ else
+ goto <bb 4>;
+ # SUCC: 3 [10.0%] (true,exec) 4 [90.0%] (false,exec)
+
+ # BLOCK 3 freq:1000
+ # PRED: 2 [10.0%] (true,exec)
+ # .MEMD.3923_15 = VDEF <.MEMD.3923_14>
+ # USE = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ # CLB = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ freeD.898 (ctxD.2601_5(D));
+ goto <bb 7>;
+ # SUCC: 7 [100.0%] (fallthru,exec)
+
+ # BLOCK 4 freq:9000
+ # PRED: 2 [90.0%] (false,exec)
+ # .MEMD.3923_16 = VDEF <.MEMD.3923_14>
+ # PT = nonlocal escaped
+ # USE = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ # CLB = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ fpD.2605_8 = fopenD.1805 (&fileNameD.2604[0], 0B);
+ if (fpD.2605_8 == 0B)
+ goto <bb 5>;
+ else
+ goto <bb 6>;
+ # SUCC: 5 [1.9%] (true,exec) 6 [98.1%] (false,exec)
+
+ # BLOCK 5 freq:173
+ # PRED: 4 [1.9%] (true,exec)
+ # .MEMD.3923_17 = VDEF <.MEMD.3923_16>
+ # USE = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ # CLB = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ freeD.898 (ctxD.2601_5(D));
+ goto <bb 7>;
+ # SUCC: 7 [100.0%] (fallthru,exec)
+
+ # BLOCK 6 freq:8827
+ # PRED: 4 [98.1%] (false,exec)
+ # .MEMD.3923_18 = VDEF <.MEMD.3923_16>
+ # USE = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ # CLB = nonlocal null { fileNameD.2604 D.3926 } (restr)
+ fooD.2599 (outputFileNameD.2600_2(D), fpD.2605_8);
+ # SUCC: 7 [100.0%] (fallthru,exec)
+
+ # BLOCK 7 freq:10000
+ # PRED: 3 [100.0%] (fallthru,exec) 5 [100.0%] (fallthru,exec)
+ 6 [100.0%] (fallthru,exec)
+ # PT = nonlocal null
+
+ # ctxD.2601_1 = PHI <0B(3), 0B(5), ctxD.2601_5(D)(6)>
+ # .MEMD.3923_11 = PHI <.MEMD.3923_15(3), .MEMD.3923_17(5),
+ .MEMD.3923_18(6)>
+ # VUSE <.MEMD.3923_11>
+ return ctxD.2601_1;
+ # SUCC: EXIT [100.0%]
+ }
+
+ bb 3 and bb 5 can be merged. The blocks have different predecessors, but the
+ same successors, and the same operations.
+
+
+ CONTEXT
+
+ A technique called tail merging (or cross jumping) can fix the example
+ above. For a block, we look for common code at the end (the tail) of the
+ predecessor blocks, and insert jumps from one block to the other.
+ The example is a special case for tail merging, in that 2 whole blocks
+ can be merged, rather than just the end parts of it.
+ We currently only focus on whole block merging, so in that sense
+ calling this pass tail merge is a bit of a misnomer.
+
+ We distinguish 2 kinds of situations in which blocks can be merged:
+ - same operations, same predecessors. The successor edges coming from one
+ block are redirected to come from the other block.
+ - same operations, same successors. The predecessor edges entering one block
+ are redirected to enter the other block. Note that this operation might
+ involve introducing phi operations.
+
+ For efficient implementation, we would like to value numbers the blocks, and
+ have a comparison operator that tells us whether the blocks are equal.
+ Besides being runtime efficient, block value numbering should also abstract
+ from irrelevant differences in order of operations, much like normal value
+ numbering abstracts from irrelevant order of operations.
+
+ For the first situation (same_operations, same predecessors), normal value
+ numbering fits well. We can calculate a block value number based on the
+ value numbers of the defs and vdefs.
+
+ For the second situation (same operations, same successors), this approach
+ doesn't work so well. We can illustrate this using the example. The calls
+ to free use different vdefs: MEMD.3923_16 and MEMD.3923_14, and these will
+ remain different in value numbering, since they represent different memory
+ states. So the resulting vdefs of the frees will be different in value
+ numbering, so the block value numbers will be different.
+
+ The reason why we call the blocks equal is not because they define the same
+ values, but because uses in the blocks use (possibly different) defs in the
+ same way. To be able to detect this efficiently, we need to do some kind of
+ reverse value numbering, meaning number the uses rather than the defs, and
+ calculate a block value number based on the value number of the uses.
+ Ideally, a block comparison operator will also indicate which phis are needed
+ to merge the blocks.
+
+ For the moment, we don't do block value numbering, but we do insn-by-insn
+ matching, using scc value numbers to match operations with results, and
+ structural comparison otherwise, while ignoring vop mismatches.
+
+
+ IMPLEMENTATION
+
+ 1. The pass first determines all groups of blocks with the same successor
+ blocks.
+ 2. Within each group, it tries to determine clusters of equal basic blocks.
+ 3. The clusters are applied.
+ 4. The same successor groups are updated.
+ 5. This process is repeated from 2 onwards, until no more changes.
+
+
+ LIMITATIONS/TODO
+
+ - block only
+ - handles only 'same operations, same successors'.
+ It handles same predecessors as a special subcase though.
+ - does not implement the reverse value numbering and block value numbering.
+ - does not abstract from statement order. In order to do this, we need to
+ abstract from statement order in the hash function, and bb comparison
+ functions.
+ - improve memory allocation: use garbage collected memory, obstacks,
+ allocpools where appropriate.
+ - no insertion of gimple_reg phis, We only introduce vop-phis.
+ - handle blocks with gimple_reg phi_nodes.
+
+
+ SWITCHES
+
+ - ftree-tail-merge. On at -O2. We may have to enable it only at -Os. */
+
+#include "config.h"
+#include "system.h"
+#include "coretypes.h"
+#include "tm.h"
+#include "tree.h"
+#include "tm_p.h"
+#include "basic-block.h"
+#include "output.h"
+#include "flags.h"
+#include "function.h"
+#include "tree-flow.h"
+#include "timevar.h"
+#include "bitmap.h"
+#include "tree-ssa-alias.h"
+#include "params.h"
+#include "tree-pretty-print.h"
+#include "hashtab.h"
+#include "gimple-pretty-print.h"
+#include "tree-ssa-sccvn.h"
+#include "tree-dump.h"
+
+/* Describes a group of bbs with the same successors. The successor bbs are
+ cached in succs, and the successor edge flags are cached in succ_flags.
+ If a bb has the EDGE_TRUE/VALSE_VALUE flags swapped compared to succ_flags,
+ it's marked in inverse.
+ Additionally, the hash value for the struct is cached in hashval, and
+ in_worklist indicates whether it's currently part of worklist. */
+
+struct same_succ
+{
+ /* The bbs that have the same successor bbs. */
+ bitmap bbs;
+ /* The successor bbs. */
+ bitmap succs;
+ /* Indicates whether the EDGE_TRUE/FALSE_VALUEs of succ_flags are swapped for
+ bb. */
+ bitmap inverse;
+ /* The edge flags for each of the successor bbs. */
+ VEC (int, heap) *succ_flags;
+ /* Indicates whether the struct is currently in the worklist. */
+ bool in_worklist;
+ /* The hash value of the struct. */
+ hashval_t hashval;
+};
+typedef struct same_succ *same_succ_t;
+typedef const struct same_succ *const_same_succ_t;
+
+/* A group of bbs where 1 bb from bbs can replace the other bbs. */
+
+struct bb_cluster
+{
+ /* The bbs in the cluster. */
+ bitmap bbs;
+ /* The preds of the bbs in the cluster. */
+ bitmap preds;
+ /* index in all_clusters vector. */
+ int index;
+};
+typedef struct bb_cluster *bb_cluster_t;
+typedef const struct bb_cluster *const_bb_cluster_t;
+
+/* Per bb-info. */
+
+struct aux_bb_info
+{
+ /* The number of non-debug statements in the bb. */
+ int size;
+ /* The same_succ that this bb is a member of. */
+ same_succ_t same_succ;
+ /* The cluster that this bb is a member of. */
+ bb_cluster_t cluster;
+ /* The vop state at the exit of a bb. This is shortlived data, used to
+ communicate data between update_block_by and update_vuses. */
+ tree vop_at_exit;
+};
+
+/* Macros to access the fields of struct aux_bb_info. */
+
+#define BB_SIZE(bb) (((struct aux_bb_info *)bb->aux)->size)
+#define BB_SAME_SUCC(bb) (((struct aux_bb_info *)bb->aux)->same_succ)
+#define BB_CLUSTER(bb) (((struct aux_bb_info *)bb->aux)->cluster)
+#define BB_VOP_AT_EXIT(bb) (((struct aux_bb_info *)bb->aux)->vop_at_exit)
+
+/* VAL1 and VAL2 are either:
+ - uses in BB1 and BB2, or
+ - phi alternatives for BB1 and BB2.
+ SAME_PREDS indicates whether BB1 and BB2 have the same predecessors.
+ Return true if the uses have the same gvn value, and if the corresponding
+ defs can be used in both BB1 and BB2. */
+
+static bool
+gvn_uses_equal (tree val1, tree val2, basic_block bb1,
+ basic_block bb2, bool same_preds)
+{
+ gcc_checking_assert (val1 != NULL_TREE && val2 != NULL_TREE);
+
+ if (val1 == val2)
+ return true;
+
+ if (vn_valueize (val1) != vn_valueize (val2))
+ return false;
+
+ /* If BB1 and BB2 have the same predecessors, the same values are defined at
+ entry of BB1 and BB2. Otherwise, we need to check. */
+
+ if (TREE_CODE (val1) == SSA_NAME)
+ {
+ if (!same_preds
+ && !SSA_NAME_IS_DEFAULT_DEF (val1)
+ && !dominated_by_p (CDI_DOMINATORS, bb2,
+ gimple_bb (SSA_NAME_DEF_STMT (val1))))
+ return false;
+ }
+ else if (!CONSTANT_CLASS_P (val1))
+ return false;
+
+ if (TREE_CODE (val2) == SSA_NAME)
+ {
+ if (!same_preds
+ && !SSA_NAME_IS_DEFAULT_DEF (val2)
+ && !dominated_by_p (CDI_DOMINATORS, bb1,
+ gimple_bb (SSA_NAME_DEF_STMT (val2))))
+ return false;
+ }
+ else if (!CONSTANT_CLASS_P (val2))
+ return false;
+
+ return true;
+}
+
+/* Prints E to FILE. */
+
+static void
+same_succ_print (FILE *file, const same_succ_t e)
+{
+ unsigned int i;
+ bitmap_print (file, e->bbs, "bbs:", "\n");
+ bitmap_print (file, e->succs, "succs:", "\n");
+ bitmap_print (file, e->inverse, "inverse:", "\n");
+ fprintf (file, "flags:");
+ for (i = 0; i < VEC_length (int, e->succ_flags); ++i)
+ fprintf (file, " %x", VEC_index (int, e->succ_flags, i));
+ fprintf (file, "\n");
+}
+
+/* Prints same_succ VE to VFILE. */
+
+static int
+same_succ_print_traverse (void **ve, void *vfile)
+{
+ const same_succ_t e = *((const same_succ_t *)ve);
+ FILE *file = ((FILE*)vfile);
+ same_succ_print (file, e);
+ return 1;
+}
+
+/* Calculates hash value for same_succ VE. */
+
+static hashval_t
+same_succ_hash (const void *ve)
+{
+ const_same_succ_t e = (const_same_succ_t)ve;
+ hashval_t hashval = bitmap_hash (e->succs);
+ int flags;
+ unsigned int i;
+ unsigned int first = bitmap_first_set_bit (e->bbs);
+ basic_block bb = BASIC_BLOCK (first);
+ int size = 0;
+ gimple_stmt_iterator gsi;
+ gimple stmt;
+ tree arg;
+
+ for (gsi = gsi_start_nondebug_bb (bb);
+ !gsi_end_p (gsi); gsi_next_nondebug (&gsi))
+ {
+ size++;
+ stmt = gsi_stmt (gsi);
+ hashval = iterative_hash_hashval_t (gimple_code (stmt), hashval);
+ if (is_gimple_assign (stmt))
+ hashval = iterative_hash_hashval_t (gimple_assign_rhs_code (stmt),
+ hashval);
+ if (!is_gimple_call (stmt))
+ continue;
+ if (gimple_call_internal_p (stmt))
+ hashval = iterative_hash_hashval_t
+ ((hashval_t) gimple_call_internal_fn (stmt), hashval);
+ else
+ hashval = iterative_hash_expr (gimple_call_fn (stmt), hashval);
+ for (i = 0; i < gimple_call_num_args (stmt); i++)
+ {
+ arg = gimple_call_arg (stmt, i);
+ arg = vn_valueize (arg);
+ hashval = iterative_hash_expr (arg, hashval);
+ }
+ }
+ hashval = iterative_hash_hashval_t (size, hashval);
+ BB_SIZE (bb) = size;
+
+ for (i = 0; i < VEC_length (int, e->succ_flags); ++i)
+ {
+ flags = VEC_index (int, e->succ_flags, i);
+ flags = flags & ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
+ hashval = iterative_hash_hashval_t (flags, hashval);
+ }
+ return hashval;
+}
+
+/* Returns true if E1 and E2 have 2 successors, and if the successor flags
+ are inverse for the EDGE_TRUE_VALUE and EDGE_FALSE_VALUE flags, and equal for
+ the other edge flags. */
+
+static bool
+inverse_flags (const_same_succ_t e1, const_same_succ_t e2)
+{
+ int f1a, f1b, f2a, f2b;
+ int mask = ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE);
+
+ if (VEC_length (int, e1->succ_flags) != 2)
+ return false;
+
+ f1a = VEC_index (int, e1->succ_flags, 0);
+ f1b = VEC_index (int, e1->succ_flags, 1);
+ f2a = VEC_index (int, e2->succ_flags, 0);
+ f2b = VEC_index (int, e2->succ_flags, 1);
+
+ if (f1a == f2a && f1b == f2b)
+ return false;
+
+ return (f1a & mask) == (f2a & mask) && (f1b & mask) == (f2b & mask);
+}
+
+/* Compares SAME_SUCCs VE1 and VE2. */
+
+static int
+same_succ_equal (const void *ve1, const void *ve2)
+{
+ const_same_succ_t e1 = (const_same_succ_t)ve1;
+ const_same_succ_t e2 = (const_same_succ_t)ve2;
+ unsigned int i, first1, first2;
+ gimple_stmt_iterator gsi1, gsi2;
+ gimple s1, s2;
+ basic_block bb1, bb2;
+
+ if (e1->hashval != e2->hashval)
+ return 0;
+
+ if (bitmap_bit_p (e1->bbs, ENTRY_BLOCK)
+ || bitmap_bit_p (e1->bbs, EXIT_BLOCK)
+ || bitmap_bit_p (e2->bbs, ENTRY_BLOCK)
+ || bitmap_bit_p (e2->bbs, EXIT_BLOCK))
+ return 0;
+
+ if (VEC_length (int, e1->succ_flags) != VEC_length (int, e2->succ_flags))
+ return 0;
+
+ if (!bitmap_equal_p (e1->succs, e2->succs))
+ return 0;
+
+ if (!inverse_flags (e1, e2))
+ {
+ for (i = 0; i < VEC_length (int, e1->succ_flags); ++i)
+ if (VEC_index (int, e1->succ_flags, i)
+ != VEC_index (int, e1->succ_flags, i))
+ return 0;
+ }
+
+ first1 = bitmap_first_set_bit (e1->bbs);
+ first2 = bitmap_first_set_bit (e2->bbs);
+
+ bb1 = BASIC_BLOCK (first1);
+ bb2 = BASIC_BLOCK (first2);
+
+ if (BB_SIZE (bb1) != BB_SIZE (bb2))
+ return 0;
+
+ gsi1 = gsi_start_nondebug_bb (bb1);
+ gsi2 = gsi_start_nondebug_bb (bb2);
+ while (!(gsi_end_p (gsi1) || gsi_end_p (gsi2)))
+ {
+ s1 = gsi_stmt (gsi1);
+ s2 = gsi_stmt (gsi2);
+ if (gimple_code (s1) != gimple_code (s2))
+ return 0;
+ if (is_gimple_call (s1) && !gimple_call_same_target_p (s1, s2))
+ return 0;
+ gsi_next_nondebug (&gsi1);
+ gsi_next_nondebug (&gsi2);
+ }
+
+ return 1;
+}
+
+/* Alloc and init a new SAME_SUCC. */
+
+static same_succ_t
+same_succ_alloc (void)
+{
+ same_succ_t same = XNEW (struct same_succ);
+
+ same->bbs = BITMAP_ALLOC (NULL);
+ same->succs = BITMAP_ALLOC (NULL);
+ same->inverse = BITMAP_ALLOC (NULL);
+ same->succ_flags = VEC_alloc (int, heap, 10);
+ same->in_worklist = false;
+
+ return same;
+}
+
+/* Delete same_succ VE. */
+
+static void
+same_succ_delete (void *ve)
+{
+ same_succ_t e = (same_succ_t)ve;
+
+ BITMAP_FREE (e->bbs);
+ BITMAP_FREE (e->succs);
+ BITMAP_FREE (e->inverse);
+ VEC_free (int, heap, e->succ_flags);
+
+ XDELETE (ve);
+}
+
+/* Reset same_succ SAME. */
+
+static void
+same_succ_reset (same_succ_t same)
+{
+ bitmap_clear (same->bbs);
+ bitmap_clear (same->succs);
+ bitmap_clear (same->inverse);
+ VEC_truncate (int, same->succ_flags, 0);
+}
+
+/* Hash table with all same_succ entries. */
+
+static htab_t same_succ_htab;
+
+/* Array that is used to store the edge flags for a successor. */
+
+static int *same_succ_edge_flags;
+
+/* Bitmap that is used to mark bbs that are recently deleted. */
+
+static bitmap deleted_bbs;
+
+/* Bitmap that is used to mark predecessors of bbs that are
+ deleted. */
+
+static bitmap deleted_bb_preds;
+
+/* Prints same_succ_htab to stderr. */
+
+extern void debug_same_succ (void);
+DEBUG_FUNCTION void
+debug_same_succ ( void)
+{
+ htab_traverse (same_succ_htab, same_succ_print_traverse, stderr);
+}
+
+DEF_VEC_P (same_succ_t);
+DEF_VEC_ALLOC_P (same_succ_t, heap);
+
+/* Vector of bbs to process. */
+
+static VEC (same_succ_t, heap) *worklist;
+
+/* Prints worklist to FILE. */
+
+static void
+print_worklist (FILE *file)
+{
+ unsigned int i;
+ for (i = 0; i < VEC_length (same_succ_t, worklist); ++i)
+ same_succ_print (file, VEC_index (same_succ_t, worklist, i));
+}
+
+/* Adds SAME to worklist. */
+
+static void
+add_to_worklist (same_succ_t same)
+{
+ if (same->in_worklist)
+ return;
+
+ if (bitmap_count_bits (same->bbs) < 2)
+ return;
+
+ same->in_worklist = true;
+ VEC_safe_push (same_succ_t, heap, worklist, same);
+}
+
+/* Add BB to same_succ_htab. */
+
+static void
+find_same_succ_bb (basic_block bb, same_succ_t *same_p)
+{
+ unsigned int j;
+ bitmap_iterator bj;
+ same_succ_t same = *same_p;
+ same_succ_t *slot;
+ edge_iterator ei;
+ edge e;
+
+ if (bb == NULL)
+ return;
+ bitmap_set_bit (same->bbs, bb->index);
+ FOR_EACH_EDGE (e, ei, bb->succs)
+ {
+ int index = e->dest->index;
+ bitmap_set_bit (same->succs, index);
+ same_succ_edge_flags[index] = e->flags;
+ }
+ EXECUTE_IF_SET_IN_BITMAP (same->succs, 0, j, bj)
+ VEC_safe_push (int, heap, same->succ_flags, same_succ_edge_flags[j]);
+
+ same->hashval = same_succ_hash (same);
+
+ slot = (same_succ_t *) htab_find_slot_with_hash (same_succ_htab, same,
+ same->hashval, INSERT);
+ if (*slot == NULL)
+ {
+ *slot = same;
+ BB_SAME_SUCC (bb) = same;
+ add_to_worklist (same);
+ *same_p = NULL;
+ }
+ else
+ {
+ bitmap_set_bit ((*slot)->bbs, bb->index);
+ BB_SAME_SUCC (bb) = *slot;
+ add_to_worklist (*slot);
+ if (inverse_flags (same, *slot))
+ bitmap_set_bit ((*slot)->inverse, bb->index);
+ same_succ_reset (same);
+ }
+}
+
+/* Find bbs with same successors. */
+
+static void
+find_same_succ (void)
+{
+ same_succ_t same = same_succ_alloc ();
+ basic_block bb;
+
+ FOR_EACH_BB (bb)
+ {
+ find_same_succ_bb (bb, &same);
+ if (same == NULL)
+ same = same_succ_alloc ();
+ }
+
+ same_succ_delete (same);
+}
+
+/* Initializes worklist administration. */
+
+static void
+init_worklist (void)
+{
+ alloc_aux_for_blocks (sizeof (struct aux_bb_info));
+ same_succ_htab
+ = htab_create (n_basic_blocks, same_succ_hash, same_succ_equal,
+ same_succ_delete);
+ same_succ_edge_flags = XCNEWVEC (int, last_basic_block);
+ deleted_bbs = BITMAP_ALLOC (NULL);
+ deleted_bb_preds = BITMAP_ALLOC (NULL);
+ worklist = VEC_alloc (same_succ_t, heap, n_basic_blocks);
+ find_same_succ ();
+
+ if (dump_file)
+ {
+ fprintf (dump_file, "initial worklist:\n");
+ print_worklist (dump_file);
+ }
+}
+
+/* Deletes worklist administration. */
+
+static void
+delete_worklist (void)
+{
+ free_aux_for_blocks ();
+ htab_delete (same_succ_htab);
+ same_succ_htab = NULL;
+ XDELETEVEC (same_succ_edge_flags);
+ same_succ_edge_flags = NULL;
+ BITMAP_FREE (deleted_bbs);
+ BITMAP_FREE (deleted_bb_preds);
+ VEC_free (same_succ_t, heap, worklist);
+}
+
+/* Mark BB as deleted, and mark its predecessors. */
+
+static void
+delete_basic_block_same_succ (basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+
+ bitmap_set_bit (deleted_bbs, bb->index);
+
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ bitmap_set_bit (deleted_bb_preds, e->src->index);
+}
+
+/* Removes all bbs in BBS from their corresponding same_succ. */
+
+static void
+same_succ_flush_bbs (bitmap bbs)
+{
+ unsigned int i;
+ bitmap_iterator bi;
+
+ EXECUTE_IF_SET_IN_BITMAP (bbs, 0, i, bi)
+ {
+ basic_block bb = BASIC_BLOCK (i);
+ same_succ_t same = BB_SAME_SUCC (bb);
+ BB_SAME_SUCC (bb) = NULL;
+ if (bitmap_single_bit_set_p (same->bbs))
+ htab_remove_elt_with_hash (same_succ_htab, same, same->hashval);
+ else
+ bitmap_clear_bit (same->bbs, i);
+ }
+}
+
+/* For deleted_bb_preds, find bbs with same successors. */
+
+static void
+update_worklist (void)
+{
+ unsigned int i;
+ bitmap_iterator bi;
+ basic_block bb;
+ same_succ_t same;
+
+ bitmap_and_compl_into (deleted_bb_preds, deleted_bbs);
+ bitmap_clear_bit (deleted_bb_preds, ENTRY_BLOCK);
+ same_succ_flush_bbs (deleted_bbs);
+ same_succ_flush_bbs (deleted_bb_preds);
+
+ EXECUTE_IF_SET_IN_BITMAP (deleted_bbs, 0, i, bi)
+ delete_basic_block (BASIC_BLOCK (i));
+
+ same = same_succ_alloc ();
+ EXECUTE_IF_SET_IN_BITMAP (deleted_bb_preds, 0, i, bi)
+ {
+ bb = BASIC_BLOCK (i);
+ gcc_assert (bb != NULL);
+ find_same_succ_bb (bb, &same);
+ if (same == NULL)
+ same = same_succ_alloc ();
+ }
+ same_succ_delete (same);
+
+ bitmap_clear (deleted_bbs);
+ bitmap_clear (deleted_bb_preds);
+}
+
+/* Prints cluster C to FILE. */
+
+static void
+print_cluster (FILE *file, bb_cluster_t c)
+{
+ if (c == NULL)
+ return;
+ bitmap_print (file, c->bbs, "bbs:", "\n");
+ bitmap_print (file, c->preds, "preds:", "\n");
+}
+
+/* Prints cluster C to stderr. */
+
+extern void debug_cluster (bb_cluster_t);
+DEBUG_FUNCTION void
+debug_cluster (bb_cluster_t c)
+{
+ print_cluster (stderr, c);
+}
+
+/* Returns true if bb1 and bb2 have the same predecessors. */
+
+static bool
+same_predecessors (basic_block bb1, basic_block bb2)
+{
+ edge e;
+ edge_iterator ei;
+ unsigned int n1 = EDGE_COUNT (bb1->preds), n2 = EDGE_COUNT (bb2->preds);
+
+ if (n1 != n2)
+ return false;
+
+ FOR_EACH_EDGE (e, ei, bb1->preds)
+ if (!find_edge (e->src, bb2))
+ return false;
+
+ return true;
+}
+
+/* Add BB to cluster C. Sets BB in C->bbs, and preds of BB in C->preds. */
+
+static void
+add_bb_to_cluster (bb_cluster_t c, basic_block bb)
+{
+ edge e;
+ edge_iterator ei;
+
+ bitmap_set_bit (c->bbs, bb->index);
+
+ FOR_EACH_EDGE (e, ei, bb->preds)
+ bitmap_set_bit (c->preds, e->src->index);
+}
+
+/* Allocate and init new cluster. */
+
+static bb_cluster_t
+new_cluster (void)
+{
+ bb_cluster_t c;
+ c = XCNEW (struct bb_cluster);
+ c->bbs = BITMAP_ALLOC (NULL);
+ c->preds = BITMAP_ALLOC (NULL);
+ return c;
+}
+
+/* Delete clusters. */
+
+static void
+delete_cluster (bb_cluster_t c)
+{
+ if (c == NULL)
+ return;
+ BITMAP_FREE (c->bbs);
+ BITMAP_FREE (c->preds);
+ XDELETE (c);
+}
+
+DEF_VEC_P (bb_cluster_t);
+DEF_VEC_ALLOC_P (bb_cluster_t, heap);
+
+/* Array that contains all clusters. */
+
+static VEC (bb_cluster_t, heap) *all_clusters;
+
+/* Allocate all cluster vectors. */
+
+static void
+alloc_cluster_vectors (void)
+{
+ all_clusters = VEC_alloc (bb_cluster_t, heap, n_basic_blocks);
+}
+
+/* Reset all cluster vectors. */
+
+static void
+reset_cluster_vectors (void)
+{
+ unsigned int i;
+ basic_block bb;
+ for (i = 0; i < VEC_length (bb_cluster_t, all_clusters); ++i)
+ delete_cluster (VEC_index (bb_cluster_t, all_clusters, i));
+ VEC_truncate (bb_cluster_t, all_clusters, 0);
+ FOR_EACH_BB (bb)
+ BB_CLUSTER (bb) = NULL;
+}
+
+/* Delete all cluster vectors. */
+
+static void
+delete_cluster_vectors (void)
+{
+ unsigned int i;
+ for (i = 0; i < VEC_length (bb_cluster_t, all_clusters); ++i)
+ delete_cluster (VEC_index (bb_cluster_t, all_clusters, i));
+ VEC_free (bb_cluster_t, heap, all_clusters);
+}
+
+/* Merge cluster C2 into C1. */
+
+static void
+merge_clusters (bb_cluster_t c1, bb_cluster_t c2)
+{
+ bitmap_ior_into (c1->bbs, c2->bbs);
+ bitmap_ior_into (c1->preds, c2->preds);
+}
+
+/* Register equivalence of BB1 and BB2 (members of cluster C). Store c in
+ all_clusters, or merge c with existing cluster. */
+
+static void
+set_cluster (basic_block bb1, basic_block bb2)
+{
+ basic_block merge_bb, other_bb;
+ bb_cluster_t merge, old, c;
+
+ if (BB_CLUSTER (bb1) == NULL && BB_CLUSTER (bb2) == NULL)
+ {
+ c = new_cluster ();
+ add_bb_to_cluster (c, bb1);
+ add_bb_to_cluster (c, bb2);
+ BB_CLUSTER (bb1) = c;
+ BB_CLUSTER (bb2) = c;
+ c->index = VEC_length (bb_cluster_t, all_clusters);
+ VEC_safe_push (bb_cluster_t, heap, all_clusters, c);
+ }
+ else if (BB_CLUSTER (bb1) == NULL || BB_CLUSTER (bb2) == NULL)
+ {
+ merge_bb = BB_CLUSTER (bb1) == NULL ? bb2 : bb1;
+ other_bb = BB_CLUSTER (bb1) == NULL ? bb1 : bb2;
+ merge = BB_CLUSTER (merge_bb);
+ add_bb_to_cluster (merge, other_bb);
+ BB_CLUSTER (other_bb) = merge;
+ }
+ else if (BB_CLUSTER (bb1) != BB_CLUSTER (bb2))
+ {
+ unsigned int i;
+ bitmap_iterator bi;
+
+ old = BB_CLUSTER (bb2);
+ merge = BB_CLUSTER (bb1);
+ merge_clusters (merge, old);
+ EXECUTE_IF_SET_IN_BITMAP (old->bbs, 0, i, bi)
+ BB_CLUSTER (BASIC_BLOCK (i)) = merge;
+ VEC_replace (bb_cluster_t, all_clusters, old->index, NULL);
+ delete_cluster (old);
+ }
+ else
+ gcc_unreachable ();
+}
+
+/* Return true if gimple statements S1 and S2 are equal. SAME_PREDS indicates
+ whether gimple_bb (s1) and gimple_bb (s2) (members of SAME_SUCC) have the
+ same predecessors. */
+
+static bool
+gimple_equal_p (same_succ_t same_succ, gimple s1, gimple s2, bool same_preds)
+{
+ unsigned int i;
+ tree lhs1, lhs2;
+ basic_block bb1 = gimple_bb (s1), bb2 = gimple_bb (s2);
+ tree t1, t2;
+ bool equal, inv_cond;
+ enum tree_code code1, code2;
+
+ if (gimple_code (s1) != gimple_code (s2))
+ return false;
+
+ switch (gimple_code (s1))
+ {
+ case GIMPLE_CALL:
+ if (gimple_call_num_args (s1) != gimple_call_num_args (s2))
+ return false;
+ if (!gimple_call_same_target_p (s1, s2))
+ return false;
+
+ equal = true;
+ for (i = 0; i < gimple_call_num_args (s1); ++i)
+ {
+ t1 = gimple_call_arg (s1, i);
+ t2 = gimple_call_arg (s2, i);
+ if (operand_equal_p (t1, t2, 0))
+ continue;
+ if (gvn_uses_equal (t1, t2, bb1, bb2, same_preds))
+ continue;
+ equal = false;
+ break;
+ }
+ if (equal)
+ return true;
+
+ lhs1 = gimple_get_lhs (s1);
+ lhs2 = gimple_get_lhs (s2);
+ return (lhs1 != NULL_TREE && lhs2 != NULL_TREE && same_preds
+ && TREE_CODE (lhs1) == SSA_NAME && TREE_CODE (lhs2) == SSA_NAME
+ && vn_valueize (lhs1) == vn_valueize (lhs2));
+
+ case GIMPLE_ASSIGN:
+ lhs1 = gimple_get_lhs (s1);
+ lhs2 = gimple_get_lhs (s2);
+ return (same_preds && TREE_CODE (lhs1) == SSA_NAME
+ && TREE_CODE (lhs2) == SSA_NAME
+ && vn_valueize (lhs1) == vn_valueize (lhs2));
+
+ case GIMPLE_COND:
+ t1 = gimple_cond_lhs (s1);
+ t2 = gimple_cond_lhs (s2);
+ if (!operand_equal_p (t1, t2, 0)
+ && !gvn_uses_equal (t1, t2, bb1, bb2, same_preds))
+ return false;
+
+ t1 = gimple_cond_rhs (s1);
+ t2 = gimple_cond_rhs (s2);
+ if (!operand_equal_p (t1, t2, 0)
+ && !gvn_uses_equal (t1, t2, bb1, bb2, same_preds))
+ return false;
+
+ code1 = gimple_expr_code (s1);
+ code2 = gimple_expr_code (s2);
+ inv_cond = (bitmap_bit_p (same_succ->inverse, bb1->index)
+ != bitmap_bit_p (same_succ->inverse, bb2->index));
+ if (inv_cond)
+ {
+ bool honor_nans
+ = HONOR_NANS (TYPE_MODE (TREE_TYPE (gimple_cond_lhs (s1))));
+ code2 = invert_tree_comparison (code2, honor_nans);
+ }
+ return code1 == code2;
+
+ default:
+ return false;
+ }
+}
+
+/* Determines whether BB1 and BB2 (members of same_succ) are duplicates. If so,
+ clusters them. SAME_PREDS indicates whether BB1 and BB2 have the same
+ predecessors. */
+
+static void
+find_duplicate (same_succ_t same_succ, basic_block bb1, basic_block bb2,
+ bool same_preds)
+{
+ gimple_stmt_iterator gsi1 = gsi_last_nondebug_bb (bb1);
+ gimple_stmt_iterator gsi2 = gsi_last_nondebug_bb (bb2);
+ bool end1 = gsi_end_p (gsi1);
+ bool end2 = gsi_end_p (gsi2);
+
+ while (!end1 && !end2)
+ {
+ if (!gimple_equal_p (same_succ, gsi_stmt (gsi1), gsi_stmt (gsi2),
+ same_preds))
+ return;
+
+ gsi_prev_nondebug (&gsi1);
+ gsi_prev_nondebug (&gsi2);
+ end1 = gsi_end_p (gsi1);
+ end2 = gsi_end_p (gsi2);
+ }
+
+ if (!(end1 && end2))
+ return;
+
+ if (dump_file)
+ fprintf (dump_file, "find_duplicates: <bb %d> duplicate of <bb %d>\n",
+ bb1->index, bb2->index);
+
+ set_cluster (bb1, bb2);
+}
+
+/* Returns whether for all phis in DEST the phi alternatives for E1 and
+ E2 are equal. SAME_PREDS indicates whether BB1 and BB2 have the same
+ predecessors. */
+
+static bool
+same_phi_alternatives_1 (basic_block dest, edge e1, edge e2, bool same_preds)
+{
+ int n1 = e1->dest_idx, n2 = e2->dest_idx;
+ basic_block bb1 = e1->src, bb2 = e2->src;
+ gimple_stmt_iterator gsi;
+
+ for (gsi = gsi_start_phis (dest); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ gimple phi = gsi_stmt (gsi);
+ tree lhs = gimple_phi_result (phi);
+ tree val1 = gimple_phi_arg_def (phi, n1);
+ tree val2 = gimple_phi_arg_def (phi, n2);
+
+ if (!is_gimple_reg (lhs))
+ continue;
+
+ if (operand_equal_for_phi_arg_p (val1, val2))
+ continue;
+ if (gvn_uses_equal (val1, val2, bb1, bb2, same_preds))
+ continue;
+
+ return false;
+ }
+
+ return true;
+}
+
+/* Returns whether for all successors of BB1 and BB2 (members of SAME_SUCC), the
+ phi alternatives for BB1 and BB2 are equal. SAME_PREDS indicates whether BB1
+ and BB2 have the same predecessors. */
+
+static bool
+same_phi_alternatives (same_succ_t same_succ, basic_block bb1, basic_block bb2,
+ bool same_preds)
+{
+ unsigned int s;
+ bitmap_iterator bs;
+ edge e1, e2;
+ basic_block succ;
+
+ EXECUTE_IF_SET_IN_BITMAP (same_succ->succs, 0, s, bs)
+ {
+ succ = BASIC_BLOCK (s);
+ e1 = find_edge (bb1, succ);
+ e2 = find_edge (bb2, succ);
+ if (e1->flags & EDGE_COMPLEX
+ || e2->flags & EDGE_COMPLEX)
+ return false;
+
+ /* For all phis in bb, the phi alternatives for e1 and e2 need to have
+ the same value. */
+ if (!same_phi_alternatives_1 (succ, e1, e2, same_preds))
+ return false;
+ }
+
+ return true;
+}
+
+/* Return true if BB has non-vop phis. */
+
+static bool
+bb_has_non_vop_phi (basic_block bb)
+{
+ gimple_seq phis = phi_nodes (bb);
+ gimple phi;
+
+ if (phis == NULL)
+ return false;
+
+ if (!gimple_seq_singleton_p (phis))
+ return true;
+
+ phi = gimple_seq_first_stmt (phis);
+ return is_gimple_reg (gimple_phi_result (phi));
+}
+
+/* Within SAME_SUCC->bbs, find clusters of bbs which can be merged. */
+
+static void
+find_clusters_1 (same_succ_t same_succ)
+{
+ basic_block bb1, bb2;
+ unsigned int i, j;
+ bitmap_iterator bi, bj;
+ bool same_preds;
+ int nr_comparisons;
+ int max_comparisons = PARAM_VALUE (PARAM_MAX_TAIL_MERGE_COMPARISONS);
+
+ if (same_succ == NULL)
+ return;
+
+ EXECUTE_IF_SET_IN_BITMAP (same_succ->bbs, 0, i, bi)
+ {
+ bb1 = BASIC_BLOCK (i);
+
+ /* TODO: handle blocks with phi-nodes. We'll have find corresponding
+ phi-nodes in bb1 and bb2, with the same alternatives for the same
+ preds. */
+ if (bb_has_non_vop_phi (bb1))
+ continue;
+
+ nr_comparisons = 0;
+ EXECUTE_IF_SET_IN_BITMAP (same_succ->bbs, i + 1, j, bj)
+ {
+ bb2 = BASIC_BLOCK (j);
+
+ if (bb_has_non_vop_phi (bb2))
+ continue;
+
+ if (BB_CLUSTER (bb1) != NULL
+ && BB_CLUSTER (bb1) == BB_CLUSTER (bb2))
+ continue;
+
+ /* Limit quadratic behaviour. */
+ nr_comparisons++;
+ if (nr_comparisons > max_comparisons)
+ break;
+
+ same_preds = same_predecessors (bb1, bb2);
+
+ if (!(same_phi_alternatives (same_succ, bb1, bb2, same_preds)))
+ continue;
+ find_duplicate (same_succ, bb1, bb2, same_preds);
+ }
+ }
+}
+
+/* Find clusters of bbs which can be merged. */
+
+static void
+find_clusters (void)
+{
+ same_succ_t same;
+
+ while (!VEC_empty (same_succ_t, worklist))
+ {
+ same = VEC_pop (same_succ_t, worklist);
+ same->in_worklist = false;
+ if (dump_file)
+ {
+ fprintf (dump_file, "processing worklist entry\n");
+ same_succ_print (dump_file, same);
+ }
+ find_clusters_1 (same);
+ }
+}
+
+/* Merge the alias info of the calls in BB1 into the calls in BB2. */
+
+static void
+merge_calls (basic_block bb1, basic_block bb2)
+{
+ gimple_stmt_iterator gsi1 = gsi_start_nondebug_bb (bb1);
+ gimple_stmt_iterator gsi2 = gsi_start_nondebug_bb (bb2);
+ bool end1, end2;
+ gimple s1, s2;
+
+ end1 = gsi_end_p (gsi1);
+ end2 = gsi_end_p (gsi2);
+
+ while (true)
+ {
+ if (end1 && end2)
+ return;
+ gcc_assert (!end1 && !end2);
+ s1 = gsi_stmt (gsi1);
+ s2 = gsi_stmt (gsi2);
+
+ if (is_gimple_call (s1) && is_gimple_call (s2))
+ {
+ pt_solution_ior_into_shared (gimple_call_use_set (s2),
+ gimple_call_use_set (s1));
+ pt_solution_ior_into_shared (gimple_call_clobber_set (s2),
+ gimple_call_clobber_set (s1));
+ }
+ else
+ gcc_assert (!is_gimple_call (s1) && !is_gimple_call (s2));
+
+ gsi_next_nondebug (&gsi1);
+ gsi_next_nondebug (&gsi2);
+ end1 = gsi_end_p (gsi1);
+ end2 = gsi_end_p (gsi2);
+ }
+}
+
+/* Create or update a vop phi in BB2. Use VUSE1 arguments for all the
+ REDIRECTED_EDGES, or if VUSE1 is NULL_TREE, use BB_VOP_AT_EXIT. If a new
+ phis is created, use the phi instead of VUSE2 in BB2. */
+
+static void
+update_vuses (tree vuse1, tree vuse2, basic_block bb2,
+ VEC (edge,heap) *redirected_edges)
+{
+ gimple stmt, phi = NULL;
+ tree lhs, arg, current_arg;
+ unsigned int i;
+ gimple def_stmt2;
+ source_location locus1, locus2;
+ imm_use_iterator iter;
+ use_operand_p use_p;
+ edge_iterator ei;
+ edge e;
+
+ if (vuse2 == NULL_TREE)
+ return;
+
+ def_stmt2 = SSA_NAME_DEF_STMT (vuse2);
+
+ /* Update existing phi. */
+ if (gimple_bb (def_stmt2) == bb2)
+ {
+ phi = def_stmt2;
+
+ for (i = 0; i < EDGE_COUNT (redirected_edges); ++i)
+ {
+ e = VEC_index (edge, redirected_edges, i);
+ if (vuse1)
+ arg = vuse1;
+ else
+ arg = BB_VOP_AT_EXIT (e->src);
+ current_arg = PHI_ARG_DEF_FROM_EDGE (phi, e);
+ if (current_arg == NULL)
+ {
+ locus1 = gimple_location (SSA_NAME_DEF_STMT (arg));
+ add_phi_arg (phi, arg, e, locus1);
+ }
+ else
+ gcc_assert (arg == current_arg);
+ }
+ return;
+ }
+
+ /* No need to create a phi with 2 equal arguments. */
+ if (vuse1 == vuse2)
+ return;
+
+ locus2 = gimple_location (def_stmt2);
+
+ /* Create a phi, first with default argument vuse2 for all preds. */
+ lhs = make_ssa_name (SSA_NAME_VAR (vuse2), NULL);
+ VN_INFO_GET (lhs);
+ phi = create_phi_node (lhs, bb2);
+ SSA_NAME_DEF_STMT (lhs) = phi;
+ FOR_EACH_EDGE (e, ei, bb2->preds)
+ add_phi_arg (phi, vuse2, e, locus2);
+
+ /* Now overwrite the arguments associated with the redirected edges with
+ vuse1. */
+ for (i = 0; i < EDGE_COUNT (redirected_edges); ++i)
+ {
+ e = VEC_index (edge, redirected_edges, i);
+ gcc_assert (PHI_ARG_DEF_FROM_EDGE (phi, e));
+ if (vuse1)
+ arg = vuse1;
+ else
+ arg = BB_VOP_AT_EXIT (e->src);
+ SET_PHI_ARG_DEF (phi, e->dest_idx, arg);
+ locus1 = gimple_location (SSA_NAME_DEF_STMT (arg));
+ gimple_phi_arg_set_location (phi, e->dest_idx, locus1);
+ }
+
+ /* Replace uses of vuse2 in bb2 with phi. */
+ FOR_EACH_IMM_USE_STMT (stmt, iter, vuse2)
+ {
+ if (gimple_code (stmt) == GIMPLE_PHI)
+ {
+ edge e;
+ if (stmt == phi)
+ continue;
+ e = find_edge (bb2, gimple_bb (stmt));
+ if (e == NULL)
+ continue;
+ use_p = PHI_ARG_DEF_PTR_FROM_EDGE (stmt, e);
+ SET_USE (use_p, lhs);
+ update_stmt (stmt);
+ }
+ else if (gimple_bb (stmt) == bb2)
+ {
+ FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
+ SET_USE (use_p, lhs);
+ update_stmt (stmt);
+ }
+ }
+}
+
+/* Returns the vop phi of BB, if any. */
+
+static gimple
+vop_phi (basic_block bb)
+{
+ gimple stmt;
+ gimple_stmt_iterator gsi;
+ for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ stmt = gsi_stmt (gsi);
+ if (is_gimple_reg (gimple_phi_result (stmt)))
+ continue;
+ return stmt;
+ }
+ return NULL;
+}
+
+/* Scans the vdefs and vuses of the insn of BB, and returns the vop at entry in
+ VOP_AT_ENTRY, and the vop at exit in VOP_AT_EXIT. */
+
+static void
+insn_vops (basic_block bb, tree *vop_at_entry, tree *vop_at_exit)
+{
+ gimple stmt;
+ gimple_stmt_iterator gsi;
+ tree vuse, vdef;
+ tree last_vdef = NULL_TREE;
+
+ if (*vop_at_entry != NULL_TREE && *vop_at_exit != NULL_TREE)
+ return;
+
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ stmt = gsi_stmt (gsi);
+ vuse = gimple_vuse (stmt);
+ vdef = gimple_vdef (stmt);
+ if (vuse != NULL_TREE && *vop_at_entry == NULL_TREE)
+ {
+ *vop_at_entry = vuse;
+ if (*vop_at_exit != NULL_TREE)
+ return;
+ }
+ if (vdef != NULL_TREE)
+ last_vdef = vdef;
+ }
+
+ *vop_at_exit = last_vdef != NULL_TREE ? last_vdef : *vop_at_entry;
+}
+
+/* Returns the vop at entry of BB1 in VOP_AT_ENTRY1, and the one of bb2 in
+ VOP_AT_ENTRY2, where BB1 and BB2 have the same successors. */
+
+static void
+vop_at_entry (basic_block bb1, basic_block bb2, tree *vop_at_entry1,
+ tree *vop_at_entry2)
+{
+ gimple succ_phi, bb1_phi, bb2_phi;
+ basic_block succ;
+ tree vop_at_exit1 = NULL_TREE, vop_at_exit2 = NULL_TREE;
+ bool same_at_exit;
+
+ bb1_phi = vop_phi (bb1);
+ bb2_phi = vop_phi (bb2);
+
+ *vop_at_entry1 = bb1_phi != NULL ? gimple_phi_result (bb1_phi) : NULL_TREE;
+ *vop_at_entry2 = bb2_phi != NULL ? gimple_phi_result (bb2_phi) : NULL_TREE;
+
+ if (*vop_at_entry1 != NULL_TREE && *vop_at_entry2 != NULL_TREE)
+ return;
+
+ if (EDGE_COUNT (bb1->succs) != 0)
+ {
+ succ = EDGE_SUCC (bb1, 0)->dest;
+ succ_phi = vop_phi (succ);
+ if (succ_phi != NULL)
+ {
+ vop_at_exit1
+ = PHI_ARG_DEF_FROM_EDGE (succ_phi, find_edge (bb1, succ));
+ vop_at_exit2
+ = PHI_ARG_DEF_FROM_EDGE (succ_phi, find_edge (bb2, succ));
+ }
+ }
+
+ same_at_exit = vop_at_exit1 == vop_at_exit2;
+
+ if (*vop_at_entry1 == NULL_TREE && vop_at_exit1 != NULL_TREE
+ && gimple_bb (SSA_NAME_DEF_STMT (vop_at_exit1)) != bb1)
+ *vop_at_entry1 = vop_at_exit1;
+
+ if (*vop_at_entry2 == NULL_TREE && vop_at_exit2 != NULL_TREE
+ && gimple_bb (SSA_NAME_DEF_STMT (vop_at_exit2)) != bb2)
+ *vop_at_entry2 = vop_at_exit2;
+
+ if (*vop_at_entry1 != NULL_TREE && *vop_at_entry2 != NULL_TREE)
+ return;
+
+ insn_vops (bb1, vop_at_entry1, &vop_at_exit1);
+ insn_vops (bb2, vop_at_entry2, &vop_at_exit2);
+
+ if (*vop_at_entry1 != NULL_TREE && *vop_at_entry2 != NULL_TREE)
+ return;
+
+ if (same_at_exit && vop_at_exit1 != NULL_TREE
+ && *vop_at_entry2 == NULL_TREE
+ && dominated_by_p (CDI_DOMINATORS, bb2, bb1))
+ *vop_at_entry2 = vop_at_exit1;
+
+ if (same_at_exit && vop_at_exit2 != NULL_TREE
+ && *vop_at_entry1 == NULL_TREE
+ && dominated_by_p (CDI_DOMINATORS, bb1, bb2))
+ *vop_at_entry1 = vop_at_exit2;
+
+ if (*vop_at_entry1 != NULL_TREE && *vop_at_entry2 != NULL_TREE)
+ return;
+
+ gcc_assert (*vop_at_entry1 == NULL_TREE && *vop_at_entry2 == NULL_TREE);
+}
+
+/* Redirect all edges from BB1 to BB2, marks BB1 for removal, and if
+ UPDATE_VOPS, inserts vop phis. */
+
+static void
+replace_block_by (basic_block bb1, basic_block bb2, bool update_vops)
+{
+ edge pred_edge;
+ unsigned int i;
+ tree phi_vuse1, phi_vuse2, arg;
+ VEC (edge,heap) *redirected_edges = NULL;
+ edge e;
+ edge_iterator ei;
+
+ if (update_vops)
+ {
+ vop_at_entry (bb1, bb2, &phi_vuse1, &phi_vuse2);
+
+ if (phi_vuse1 != NULL_TREE
+ && gimple_bb (SSA_NAME_DEF_STMT (phi_vuse1)) == bb1)
+ {
+ FOR_EACH_EDGE (e, ei, bb1->preds)
+ {
+ arg = PHI_ARG_DEF_FROM_EDGE (SSA_NAME_DEF_STMT (phi_vuse1), e);
+ BB_VOP_AT_EXIT (e->src) = arg;
+ }
+ phi_vuse1 = NULL;
+ }
+ redirected_edges = VEC_alloc (edge, heap, 10);
+ }
+
+ delete_basic_block_same_succ (bb1);
+
+ /* Redirect the incoming edges of bb1 to bb2. */
+ for (i = EDGE_COUNT (bb1->preds); i > 0 ; --i)
+ {
+ pred_edge = EDGE_PRED (bb1, i - 1);
+ pred_edge = redirect_edge_and_branch (pred_edge, bb2);
+ gcc_assert (pred_edge != NULL);
+ if (update_vops)
+ VEC_safe_push (edge, heap, redirected_edges, pred_edge);
+ }
+
+ if (update_vops)
+ {
+ update_vuses (phi_vuse1, phi_vuse2, bb2, redirected_edges);
+ VEC_free (edge, heap, redirected_edges);
+ }
+
+ merge_calls (bb1, bb2);
+}
+
+/* Bbs for which update_debug_stmt need to be called. */
+
+static bitmap update_bbs;
+
+/* For each cluster in all_clusters, merge all cluster->bbs. Returns
+ number of bbs removed. Insert vop phis if UPDATE_VOPS. */
+
+static int
+apply_clusters (bool update_vops)
+{
+ basic_block bb1, bb2;
+ bb_cluster_t c;
+ unsigned int i, j;
+ bitmap_iterator bj;
+ int nr_bbs_removed = 0;
+
+ for (i = 0; i < VEC_length (bb_cluster_t, all_clusters); ++i)
+ {
+ c = VEC_index (bb_cluster_t, all_clusters, i);
+ if (c == NULL)
+ continue;
+
+ bb2 = BASIC_BLOCK (bitmap_first_set_bit (c->bbs));
+ gcc_assert (bb2 != NULL);
+
+ bitmap_set_bit (update_bbs, bb2->index);
+ EXECUTE_IF_SET_IN_BITMAP (c->bbs, 0, j, bj)
+ {
+ bb1 = BASIC_BLOCK (j);
+ gcc_assert (bb1 != NULL);
+ if (bb1 == bb2)
+ continue;
+
+ bitmap_clear_bit (update_bbs, bb1->index);
+ replace_block_by (bb1, bb2, update_vops);
+ nr_bbs_removed++;
+ }
+ }
+
+ return nr_bbs_removed;
+}
+
+/* Resets debug statement STMT if it has uses that are not dominated by their
+ defs. */
+
+static void
+update_debug_stmt (gimple stmt)
+{
+ use_operand_p use_p;
+ ssa_op_iter oi;
+ basic_block bbdef, bbuse;
+ gimple def_stmt;
+ tree name;
+
+ if (!gimple_debug_bind_p (stmt))
+ return;
+
+ bbuse = gimple_bb (stmt);
+ FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, oi, SSA_OP_USE)
+ {
+ name = USE_FROM_PTR (use_p);
+ gcc_assert (TREE_CODE (name) == SSA_NAME);
+
+ def_stmt = SSA_NAME_DEF_STMT (name);
+ gcc_assert (def_stmt != NULL);
+
+ bbdef = gimple_bb (def_stmt);
+ if (bbdef == NULL || bbuse == bbdef
+ || dominated_by_p (CDI_DOMINATORS, bbuse, bbdef))
+ continue;
+
+ gimple_debug_bind_reset_value (stmt);
+ update_stmt (stmt);
+ }
+}
+
+/* Resets all debug statements that have uses that are not
+ dominated by their defs. */
+
+static void
+update_debug_stmts (void)
+{
+ basic_block bb;
+ bitmap_iterator bi;
+ unsigned int i;
+
+ if (!MAY_HAVE_DEBUG_STMTS)
+ return;
+
+ EXECUTE_IF_SET_IN_BITMAP (update_bbs, 0, i, bi)
+ {
+ gimple stmt;
+ gimple_stmt_iterator gsi;
+
+ bb = BASIC_BLOCK (i);
+ for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
+ {
+ stmt = gsi_stmt (gsi);
+ if (!is_gimple_debug (stmt))
+ continue;
+ update_debug_stmt (stmt);
+ }
+ }
+}
+
+/* Runs tail merge optimization. */
+
+unsigned int
+tail_merge_optimize (unsigned int todo)
+{
+ int nr_bbs_removed_total = 0;
+ int nr_bbs_removed;
+ bool loop_entered = false;
+ int iteration_nr = 0;
+ bool update_vops = ((todo & TODO_update_ssa_only_virtuals) == 0
+ || !symbol_marked_for_renaming (gimple_vop (cfun)));
+
+ if (!flag_tree_tail_merge)
+ return 0;
+
+ timevar_push (TV_TREE_TAIL_MERGE);
+
+ init_worklist ();
+
+ while (!VEC_empty (same_succ_t, worklist))
+ {
+ if (!loop_entered)
+ {
+ loop_entered = true;
+ alloc_cluster_vectors ();
+ update_bbs = BITMAP_ALLOC (NULL);
+ }
+ else
+ reset_cluster_vectors ();
+
+ iteration_nr++;
+ if (dump_file)
+ fprintf (dump_file, "worklist iteration #%d\n", iteration_nr);
+
+ calculate_dominance_info (CDI_DOMINATORS);
+ find_clusters ();
+ gcc_assert (VEC_empty (same_succ_t, worklist));
+ if (VEC_empty (bb_cluster_t, all_clusters))
+ break;
+
+ nr_bbs_removed = apply_clusters (update_vops);
+ nr_bbs_removed_total += nr_bbs_removed;
+ if (nr_bbs_removed == 0)
+ break;
+
+ free_dominance_info (CDI_DOMINATORS);
+ update_worklist ();
+ }
+
+ if (dump_file)
+ fprintf (dump_file, "htab collision / search: %f\n",
+ htab_collisions (same_succ_htab));
+
+ if (nr_bbs_removed_total > 0)
+ {
+ calculate_dominance_info (CDI_DOMINATORS);
+ update_debug_stmts ();
+
+ if (dump_file && (dump_flags & TDF_DETAILS))
+ {
+ fprintf (dump_file, "Before TODOs.\n");
+ dump_function_to_file (current_function_decl, dump_file, dump_flags);
+ }
+
+ todo |= (TODO_verify_ssa | TODO_verify_stmts | TODO_verify_flow
+ | TODO_dump_func);
+ }
+
+ delete_worklist ();
+ if (loop_entered)
+ {
+ delete_cluster_vectors ();
+ BITMAP_FREE (update_bbs);
+ }
+
+ timevar_pop (TV_TREE_TAIL_MERGE);
+
+ return todo;
+}
Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c (revision 175801)
+++ gcc/tree-ssa-sccvn.c (working copy)
@@ -2872,19 +2872,6 @@ simplify_unary_expression (gimple stmt)
return NULL_TREE;
}
-/* Valueize NAME if it is an SSA name, otherwise just return it. */
-
-static inline tree
-vn_valueize (tree name)
-{
- if (TREE_CODE (name) == SSA_NAME)
- {
- tree tem = SSA_VAL (name);
- return tem == VN_TOP ? name : tem;
- }
- return name;
-}
-
/* Try to simplify RHS using equivalences and constant folding. */
static tree
Index: gcc/tree-ssa-sccvn.h
===================================================================
--- gcc/tree-ssa-sccvn.h (revision 175801)
+++ gcc/tree-ssa-sccvn.h (working copy)
@@ -209,4 +209,18 @@ unsigned int get_constant_value_id (tree
unsigned int get_or_alloc_constant_value_id (tree);
bool value_id_constant_p (unsigned int);
tree fully_constant_vn_reference_p (vn_reference_t);
+
+/* Valueize NAME if it is an SSA name, otherwise just return it. */
+
+static inline tree
+vn_valueize (tree name)
+{
+ if (TREE_CODE (name) == SSA_NAME)
+ {
+ tree tem = VN_INFO (name)->valnum;
+ return tem == VN_TOP ? name : tem;
+ }
+ return name;
+}
+
#endif /* TREE_SSA_SCCVN_H */
Index: gcc/tree-ssa-alias.h
===================================================================
--- gcc/tree-ssa-alias.h (revision 175801)
+++ gcc/tree-ssa-alias.h (working copy)
@@ -134,6 +134,8 @@ extern bool pt_solutions_same_restrict_b
extern void pt_solution_reset (struct pt_solution *);
extern void pt_solution_set (struct pt_solution *, bitmap, bool, bool);
extern void pt_solution_set_var (struct pt_solution *, tree);
+extern void pt_solution_ior_into_shared (struct pt_solution *,
+ struct pt_solution *);
extern void dump_pta_stats (FILE *);
Index: gcc/opts.c
===================================================================
--- gcc/opts.c (revision 175801)
+++ gcc/opts.c (working copy)
@@ -484,6 +484,7 @@ static const struct default_options defa
{ OPT_LEVELS_2_PLUS, OPT_falign_jumps, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_falign_labels, NULL, 1 },
{ OPT_LEVELS_2_PLUS, OPT_falign_functions, NULL, 1 },
+ { OPT_LEVELS_2_PLUS, OPT_ftree_tail_merge, NULL, 1 },
/* -O3 optimizations. */
{ OPT_LEVELS_3_PLUS, OPT_ftree_loop_distribute_patterns, NULL, 1 },
Index: gcc/timevar.def
===================================================================
--- gcc/timevar.def (revision 175801)
+++ gcc/timevar.def (working copy)
@@ -127,6 +127,7 @@ DEFTIMEVAR (TV_TREE_GIMPLIFY , "tre
DEFTIMEVAR (TV_TREE_EH , "tree eh")
DEFTIMEVAR (TV_TREE_CFG , "tree CFG construction")
DEFTIMEVAR (TV_TREE_CLEANUP_CFG , "tree CFG cleanup")
+DEFTIMEVAR (TV_TREE_TAIL_MERGE , "tree tail merge")
DEFTIMEVAR (TV_TREE_VRP , "tree VRP")
DEFTIMEVAR (TV_TREE_COPY_PROP , "tree copy propagation")
DEFTIMEVAR (TV_FIND_REFERENCED_VARS , "tree find ref. vars")
Index: gcc/tree-ssa-pre.c
===================================================================
--- gcc/tree-ssa-pre.c (revision 175801)
+++ gcc/tree-ssa-pre.c (working copy)
@@ -4935,7 +4935,6 @@ execute_pre (bool do_fre)
statistics_counter_event (cfun, "Constified", pre_stats.constified);
clear_expression_ids ();
- free_scc_vn ();
if (!do_fre)
{
remove_dead_inserted_code ();
@@ -4945,6 +4944,9 @@ execute_pre (bool do_fre)
scev_finalize ();
fini_pre (do_fre);
+ todo |= tail_merge_optimize (todo);
+ free_scc_vn ();
+
return todo;
}
Index: gcc/common.opt
===================================================================
--- gcc/common.opt (revision 175801)
+++ gcc/common.opt (working copy)
@@ -1937,6 +1937,10 @@ ftree-dominator-opts
Common Report Var(flag_tree_dom) Optimization
Enable dominator optimizations
+ftree-tail-merge
+Common Report Var(flag_tree_tail_merge) Optimization
+Enable tail merging on trees
+
ftree-dse
Common Report Var(flag_tree_dse) Optimization
Enable dead store elimination
Index: gcc/tree-flow.h
===================================================================
--- gcc/tree-flow.h (revision 175801)
+++ gcc/tree-flow.h (working copy)
@@ -806,6 +806,9 @@ bool multiplier_allowed_in_address_p (HO
unsigned multiply_by_cost (HOST_WIDE_INT, enum machine_mode, bool);
bool may_be_nonaddressable_p (tree expr);
+/* In tree-ssa-tail-merge.c. */
+extern unsigned int tail_merge_optimize (unsigned int);
+
/* In tree-ssa-threadupdate.c. */
extern bool thread_through_all_blocks (bool);
extern void register_jump_thread (edge, edge, edge);
Index: gcc/Makefile.in
===================================================================
--- gcc/Makefile.in (revision 175801)
+++ gcc/Makefile.in (working copy)
@@ -1466,6 +1466,7 @@ OBJS = \
tree-ssa-sccvn.o \
tree-ssa-sink.o \
tree-ssa-structalias.o \
+ tree-ssa-tail-merge.o \
tree-ssa-ter.o \
tree-ssa-threadedge.o \
tree-ssa-threadupdate.o \
@@ -2427,6 +2428,13 @@ stor-layout.o : stor-layout.c $(CONFIG_H
$(TREE_H) $(PARAMS_H) $(FLAGS_H) $(FUNCTION_H) $(EXPR_H) output.h $(RTL_H) \
$(GGC_H) $(TM_P_H) $(TARGET_H) langhooks.h $(REGS_H) gt-stor-layout.h \
$(DIAGNOSTIC_CORE_H) $(CGRAPH_H) $(TREE_INLINE_H) $(TREE_DUMP_H) $(GIMPLE_H)
+tree-ssa-tail-merge.o: tree-ssa-tail-merge.c \
+ $(SYSTEM_H) $(CONFIG_H) coretypes.h $(TM_H) $(BITMAP_H) \
+ $(FLAGS_H) $(TM_P_H) $(BASIC_BLOCK_H) output.h \
+ $(TREE_H) $(TREE_FLOW_H) $(TREE_INLINE_H) \
+ $(GIMPLE_H) $(FUNCTION_H) \
+ $(TIMEVAR_H) tree-ssa-sccvn.h \
+ $(CGRAPH_H) gimple-pretty-print.h tree-pretty-print.h $(PARAMS_H)
tree-ssa-structalias.o: tree-ssa-structalias.c \
$(SYSTEM_H) $(CONFIG_H) coretypes.h $(TM_H) $(GGC_H) $(OBSTACK_H) $(BITMAP_H) \
$(FLAGS_H) $(TM_P_H) $(BASIC_BLOCK_H) output.h \
Index: gcc/tree-ssa-structalias.c
===================================================================
--- gcc/tree-ssa-structalias.c (revision 175801)
+++ gcc/tree-ssa-structalias.c (working copy)
@@ -5688,6 +5688,48 @@ shared_bitmap_add (bitmap pt_vars)
*slot = (void *) sbi;
}
+/* Unshares the points-to bitmap of PT. */
+
+static void
+pt_solution_unshare (struct pt_solution *pt)
+{
+ bitmap copy;
+
+ if (pt == NULL || pt->vars == NULL || shared_bitmap_table == NULL)
+ return;
+
+ copy = BITMAP_GGC_ALLOC ();
+ bitmap_copy (pt->vars, copy);
+ pt->vars = copy;
+}
+
+/* Shares the points-to bitmap of PT. */
+
+static void
+pt_solution_share (struct pt_solution *pt)
+{
+ bitmap shared;
+
+ if (pt == NULL || pt->vars == NULL || shared_bitmap_table == NULL)
+ return;
+
+ shared = shared_bitmap_lookup (pt->vars);
+
+ if (!shared)
+ {
+ /* Share unshared bitmap. */
+ shared_bitmap_add (pt->vars);
+ return;
+ }
+
+ /* Already using shared bitmap. */
+ if (shared == pt->vars)
+ return;
+
+ /* Use shared bitmap. */
+ bitmap_clear (pt->vars);
+ pt->vars = shared;
+}
/* Set bits in INTO corresponding to the variable uids in solution set FROM. */
@@ -5734,7 +5776,6 @@ find_what_var_points_to (varinfo_t orig_
unsigned int i;
bitmap_iterator bi;
bitmap finished_solution;
- bitmap result;
varinfo_t vi;
memset (pt, 0, sizeof (struct pt_solution));
@@ -5788,17 +5829,8 @@ find_what_var_points_to (varinfo_t orig_
stats.points_to_sets_created++;
set_uids_in_ptset (finished_solution, vi->solution, pt);
- result = shared_bitmap_lookup (finished_solution);
- if (!result)
- {
- shared_bitmap_add (finished_solution);
- pt->vars = finished_solution;
- }
- else
- {
- pt->vars = result;
- bitmap_clear (finished_solution);
- }
+ pt->vars = finished_solution;
+ pt_solution_share (pt);
}
/* Given a pointer variable P, fill in its points-to set. */
@@ -5921,6 +5953,25 @@ pt_solution_ior_into (struct pt_solution
bitmap_ior_into (dest->vars, src->vars);
}
+/* Like pt_solution_ior_into, but may be used if the points-to bitmap
+ of *DEST might be shared. */
+
+void
+pt_solution_ior_into_shared (struct pt_solution *dest, struct pt_solution *src)
+{
+ if (!src->vars)
+ return;
+ if (!dest->vars)
+ {
+ dest->vars = src->vars;
+ return;
+ }
+
+ pt_solution_unshare (dest);
+ pt_solution_ior_into (dest, src);
+ pt_solution_share (dest);
+}
+
/* Return true if the points-to solution *PT is empty. */
bool
@@ -6600,6 +6651,7 @@ delete_points_to_sets (void)
unsigned int i;
htab_delete (shared_bitmap_table);
+ shared_bitmap_table = NULL;
if (dump_file && (dump_flags & TDF_STATS))
fprintf (dump_file, "Points to sets created:%d\n",
stats.points_to_sets_created);
Index: gcc/params.def
===================================================================
--- gcc/params.def (revision 175801)
+++ gcc/params.def (working copy)
@@ -892,6 +892,11 @@ DEFPARAM (PARAM_MAX_STORES_TO_SINK,
"Maximum number of conditional store pairs that can be sunk",
2, 0, 0)
+DEFPARAM (PARAM_MAX_TAIL_MERGE_COMPARISONS,
+ "max-tail-merge-comparisons",
+ "Maximum amount of similar bbs to compare a bb with",
+ 10, 0, 0)
+
/*
Local variables:
Index: gcc/doc/invoke.texi
===================================================================
--- gcc/doc/invoke.texi (revision 175801)
+++ gcc/doc/invoke.texi (working copy)
@@ -404,7 +404,7 @@ Objective-C and Objective-C++ Dialects}.
-ftree-phiprop -ftree-loop-distribution -ftree-loop-distribute-patterns @gol
-ftree-loop-ivcanon -ftree-loop-linear -ftree-loop-optimize @gol
-ftree-parallelize-loops=@var{n} -ftree-pre -ftree-pta -ftree-reassoc @gol
--ftree-sink -ftree-sra -ftree-switch-conversion @gol
+-ftree-sink -ftree-sra -ftree-switch-conversion -ftree-tail-merge @gol
-ftree-ter -ftree-vect-loop-version -ftree-vectorize -ftree-vrp @gol
-funit-at-a-time -funroll-all-loops -funroll-loops @gol
-funsafe-loop-optimizations -funsafe-math-optimizations -funswitch-loops @gol
@@ -6091,7 +6091,7 @@ also turns on the following optimization
-fsched-interblock -fsched-spec @gol
-fschedule-insns -fschedule-insns2 @gol
-fstrict-aliasing -fstrict-overflow @gol
--ftree-switch-conversion @gol
+-ftree-switch-conversion -ftree-tail-merge @gol
-ftree-pre @gol
-ftree-vrp}
@@ -6974,6 +6974,11 @@ Perform conversion of simple initializat
initializations from a scalar array. This flag is enabled by default
at @option{-O2} and higher.
+@item -ftree-tail-merge
+Merges identical blocks with same successors. This flag is enabled by default
+at @option{-O2} and higher. The run time of this pass can be limited using
+@option{max-tail-merge-comparisons} parameter.
+
@item -ftree-dce
@opindex ftree-dce
Perform dead code elimination (DCE) on trees. This flag is enabled by
@@ -8541,6 +8546,10 @@ This is used to avoid quadratic behavior
The value of 0 will avoid limiting the search, but may slow down compilation
of huge functions. The default value is 30.
+@item max-tail-merge-comparisons
+The maximum amount of similar bbs to compare a bb with. This is used to
+avoid quadratic behaviour in tree tail merging. The default value is 10.
+
@item max-unrolled-insns
The maximum number of instructions that a loop should have if that loop
is unrolled, and if the loop is unrolled, it determines how many times