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[PATCH] Small cleanups to cse.c
- From: Steven Bosscher <stevenb dot gcc at gmail dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: "Sayle, Roger" <roger at eyesopen dot com>
- Date: Sat, 25 Nov 2006 16:12:06 +0100
- Subject: [PATCH] Small cleanups to cse.c
Hi,
This patch contains four small cleanups:
* Makes us update the CFG incrementally in cse.c. I can now run
verify_flow_info at the end of cse and assert that purge_dead_edges
is a NOP. This is a required change to make CSE work on extended
basic blocks instead of an insns list.
* Removes cse_altered. Once upon a time, CSE could produce tons of
garbage. But not anymore.
* Changes the TAKEN argument of record_jump_equiv to a bool. Just
because true/false arguments shouldn't be int IMHO ;-)
* Removes the code guarded with USE_C_ALLOCA. We don't use that in
any other place in GCC. Looks like more relics from the Old Days.
This patch mostly helps reducing the size of another cse.c patch I will
submit soon, that will make CSE path following work on the CFG. That
patch is a ~2000 lines unidiff right now, but I'm trying to cut it into
manageable pieces.
Bootstrapped (c,c++,objc,fortran,java) and tested on x86_64-linux.
I'm going to commit this patch in a few days unless I hear objections.
Gr.
Steven
* cse.c (cse_altered): Remove.
(record_jump_equiv): Make true/false argument a bool instead
of an int.
(cse_insn): Don't set cse_altered. Use delete_insn_and_edges
where appropriate. Emit a new jump before the existing one
instead of after so that delete_insn_and_edges removes the
dead edges properly. Check any_condjump_p before calling
record_jump_equiv.
(cse_basic_block): Check any_condjump_p before calling
record_jump_equiv.
(cse_main): Don't set/check cse_altered. Remove USE_C_ALLOCA.
Index: cse.c
===================================================================
--- cse.c (revision 119190)
+++ cse.c (working copy)
@@ -371,11 +371,6 @@ static int max_uid;
#define INSN_CUID(INSN) (uid_cuid[INSN_UID (INSN)])
-/* Nonzero if this pass has made changes, and therefore it's
- worthwhile to run the garbage collector. */
-
-static int cse_altered;
-
/* Nonzero if cse has altered conditional jump insns
in such a way that jump optimization should be redone. */
@@ -603,7 +598,7 @@ static enum rtx_code find_comparison_arg
enum machine_mode *);
static rtx fold_rtx (rtx, rtx);
static rtx equiv_constant (rtx);
-static void record_jump_equiv (rtx, int);
+static void record_jump_equiv (rtx, bool);
static void record_jump_cond (enum rtx_code, enum machine_mode, rtx, rtx,
int);
static void cse_insn (rtx, rtx);
@@ -3694,8 +3689,8 @@ equiv_constant (rtx x)
return 0;
}
-/* Given INSN, a jump insn, PATH_TAKEN indicates if we are following the "taken"
- branch. It will be zero if not.
+/* Given INSN, a jump insn, TAKEN indicates if we are following the
+ "taken" branch.
In certain cases, this can cause us to add an equivalence. For example,
if we are following the taken case of
@@ -3706,7 +3701,7 @@ equiv_constant (rtx x)
comparison is seen later, we will know its value. */
static void
-record_jump_equiv (rtx insn, int taken)
+record_jump_equiv (rtx insn, bool taken)
{
int cond_known_true;
rtx op0, op1;
@@ -3715,9 +3710,11 @@ record_jump_equiv (rtx insn, int taken)
int reversed_nonequality = 0;
enum rtx_code code;
+#ifdef ENABLE_CHECKING
/* Ensure this is the right kind of insn. */
- if (! any_condjump_p (insn))
- return;
+ gcc_assert (any_condjump_p (insn));
+#endif
+
set = pc_set (insn);
/* See if this jump condition is known true or false. */
@@ -4942,7 +4939,6 @@ cse_insn (rtx insn, rtx libcall_insn)
/* If we made a change, recompute SRC values. */
if (src != sets[i].src)
{
- cse_altered = 1;
do_not_record = 0;
hash_arg_in_memory = 0;
sets[i].src = src;
@@ -5044,7 +5040,7 @@ cse_insn (rtx insn, rtx libcall_insn)
else if (n_sets == 1 && dest == pc_rtx && src == pc_rtx)
{
/* One less use of the label this insn used to jump to. */
- delete_insn (insn);
+ delete_insn_and_edges (insn);
cse_jumps_altered = 1;
/* No more processing for this set. */
sets[i].rtl = 0;
@@ -5071,7 +5067,7 @@ cse_insn (rtx insn, rtx libcall_insn)
{
rtx new, note;
- new = emit_jump_insn_after (gen_jump (XEXP (src, 0)), insn);
+ new = emit_jump_insn_before (gen_jump (XEXP (src, 0)), insn);
JUMP_LABEL (new) = XEXP (src, 0);
LABEL_NUSES (XEXP (src, 0))++;
@@ -5083,7 +5079,7 @@ cse_insn (rtx insn, rtx libcall_insn)
REG_NOTES (new) = note;
}
- delete_insn (insn);
+ delete_insn_and_edges (insn);
insn = new;
/* Now emit a BARRIER after the unconditional jump. */
@@ -5636,10 +5632,8 @@ cse_insn (rtx insn, rtx libcall_insn)
/* If this is a conditional jump insn, record any known equivalences due to
the condition being tested. */
- if (JUMP_P (insn)
- && n_sets == 1 && GET_CODE (x) == SET
- && GET_CODE (SET_SRC (x)) == IF_THEN_ELSE)
- record_jump_equiv (insn, 0);
+ if (n_sets == 1 && any_condjump_p (insn))
+ record_jump_equiv (insn, false);
#ifdef HAVE_cc0
/* If the previous insn set CC0 and this insn no longer references CC0,
@@ -5649,7 +5643,7 @@ cse_insn (rtx insn, rtx libcall_insn)
&& (tem = single_set (prev_insn)) != 0
&& SET_DEST (tem) == cc0_rtx
&& ! reg_mentioned_p (cc0_rtx, x))
- delete_insn (prev_insn);
+ delete_insn_and_edges (prev_insn);
prev_insn_cc0 = this_insn_cc0;
prev_insn_cc0_mode = this_insn_cc0_mode;
@@ -6016,7 +6010,6 @@ cse_main (rtx f, int nregs)
insn = f;
while (insn)
{
- cse_altered = 0;
cse_end_of_basic_block (insn, &val, flag_cse_follow_jumps);
/* If this basic block was already processed or has no sets, skip it. */
@@ -6062,13 +6055,6 @@ cse_main (rtx f, int nregs)
cse_jumps_altered |= old_cse_jumps_altered;
}
-
- if (cse_altered)
- ggc_collect ();
-
-#ifdef USE_C_ALLOCA
- alloca (0);
-#endif
}
/* Clean up. */
@@ -6130,7 +6116,8 @@ cse_basic_block (rtx from, rtx to, struc
if (status != PATH_NOT_TAKEN)
{
gcc_assert (status == PATH_TAKEN);
- record_jump_equiv (insn, 1);
+ if (any_condjump_p (insn))
+ record_jump_equiv (insn, true);
/* Set the last insn as the jump insn; it doesn't affect cc0.
Then follow this branch. */