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Re: reload inheritance error breaks openssl on s390
On Aug 9, 2006, Ian Lance Taylor <iant@google.com> wrote:
>> PR target/28146
>> * reload.h (reg_equiv_lra_tweak): New declaration.
>> * reload1.c (reg_equiv_lra_tweak): New definition.
>> (reload): Initialize it.
>> (delete_output_reload): Use it.
>> * reload.c (find_reloads_address): Set it if
>> LEGITIMIZE_RELOAD_ADDRESS changes the address.
> This patch is the right sort of thing, but I don't understand how it
> actually works. You only store a value in reg_equiv_lra_tweak if
> REGNO >= 0, but I don't see any execution path which leads to REGNO >=
> 0 when LEGITIMIZE_RELOAD_ADDRESS is called. What am I missing?
You're missing the brain-deadness that I experienced at the time I
wrote it :-(
I'd actually got away from the problem for too long, and when I got
back I found this simple, easy and wrong approach to address the
problem, that I was missing before :-), and random fluctuations in the
patterns that made to the reload pass managed to hide the problem such
that I no longer observed it. Doh!
This one does a better job, and I've actually tested it on the same
baseline tree where I'd first experienced the problem. Does this look
better for you too? :-)
I'm currently bootstrapping it on amd64-linux-gnu. If that works,
I'll give it a round of testing on a wider range of machines and then
formally submit it for inclusion.
for gcc/ChangeLog
from Alexandre Oliva <aoliva@redhat.com>
PR target/28146
* reload.h (reg_equiv_alt_mem_list): New declaration.
* reload1.c (reg_equiv_alt_mem_list): New definition.
(reload): Initialize it and release it.
(delete_output_reload): Use it.
* reload.c (push_reg_equiv_alt_mem): New function.
(find_reloads_toplev): Call it.
(find_reloads_address, find_reloads_address_1): Likewise.
(find_reloads_subreg_address): Likewise.
Index: gcc/reload1.c
===================================================================
--- gcc/reload1.c.orig 2006-08-15 07:01:19.000000000 -0300
+++ gcc/reload1.c 2006-08-16 05:46:18.000000000 -0300
@@ -123,6 +123,10 @@ rtx *reg_equiv_address;
or zero if pseudo reg N is not equivalent to a memory slot. */
rtx *reg_equiv_mem;
+/* Element N is an EXPR_LIST of REG_EQUIVs containing MEMs with
+ alternate representations of the location of pseudo reg N. */
+rtx *reg_equiv_alt_mem_list;
+
/* Widest width in which each pseudo reg is referred to (via subreg). */
static unsigned int *reg_max_ref_width;
@@ -703,6 +707,7 @@ reload (rtx first, int global)
reg_equiv_constant = XCNEWVEC (rtx, max_regno);
reg_equiv_invariant = XCNEWVEC (rtx, max_regno);
reg_equiv_mem = XCNEWVEC (rtx, max_regno);
+ reg_equiv_alt_mem_list = XCNEWVEC (rtx, max_regno);
reg_equiv_address = XCNEWVEC (rtx, max_regno);
reg_max_ref_width = XCNEWVEC (unsigned int, max_regno);
reg_old_renumber = XCNEWVEC (short, max_regno);
@@ -1260,6 +1265,11 @@ reload (rtx first, int global)
if (offsets_at)
free (offsets_at);
+ for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
+ if (reg_equiv_alt_mem_list[i])
+ free_EXPR_LIST_list (®_equiv_alt_mem_list[i]);
+ free (reg_equiv_alt_mem_list);
+
free (reg_equiv_mem);
reg_equiv_init = 0;
free (reg_equiv_address);
@@ -7849,6 +7859,11 @@ delete_output_reload (rtx insn, int j, i
n_occurrences += count_occurrences (PATTERN (insn),
eliminate_regs (substed, 0,
NULL_RTX), 0);
+ for (i1 = reg_equiv_alt_mem_list [REGNO (reg)]; i1; i1 = XEXP (i1, 1))
+ {
+ gcc_assert (!rtx_equal_p (XEXP (i1, 0), substed));
+ n_occurrences += count_occurrences (PATTERN (insn), XEXP (i1, 0), 0);
+ }
if (n_occurrences > n_inherited)
return;
Index: gcc/reload.c
===================================================================
--- gcc/reload.c.orig 2006-08-15 07:01:19.000000000 -0300
+++ gcc/reload.c 2006-08-16 05:45:02.000000000 -0300
@@ -283,6 +283,26 @@ static int find_inc_amount (rtx, rtx);
static int refers_to_mem_for_reload_p (rtx);
static int refers_to_regno_for_reload_p (unsigned int, unsigned int,
rtx, rtx *);
+
+/* Add NEW to reg_equiv_alt_mem_list[REGNO] if it's different from
+ ORIG and not present in the list yet. */
+
+static inline void
+push_reg_equiv_alt_mem (int regno, rtx new, rtx orig)
+{
+ rtx it;
+
+ if (new == orig)
+ return;
+
+ for (it = reg_equiv_alt_mem_list [regno]; it; it = XEXP (it, 1))
+ if (rtx_equal_p (XEXP (it, 0), new))
+ return;
+
+ reg_equiv_alt_mem_list [regno]
+ = alloc_EXPR_LIST (REG_EQUIV, new,
+ reg_equiv_alt_mem_list [regno]);
+}
/* Determine if any secondary reloads are needed for loading (if IN_P is
nonzero) or storing (if IN_P is zero) X to or from a reload register of
@@ -4553,6 +4573,7 @@ find_reloads_toplev (rtx x, int opnum, e
x = mem;
i = find_reloads_address (GET_MODE (x), &x, XEXP (x, 0), &XEXP (x, 0),
opnum, type, ind_levels, insn);
+ push_reg_equiv_alt_mem (regno, x, mem);
if (address_reloaded)
*address_reloaded = i;
}
@@ -4761,9 +4782,12 @@ find_reloads_address (enum machine_mode
tem = make_memloc (ad, regno);
if (! strict_memory_address_p (GET_MODE (tem), XEXP (tem, 0)))
{
+ rtx orig = tem;
+
find_reloads_address (GET_MODE (tem), &tem, XEXP (tem, 0),
&XEXP (tem, 0), opnum,
ADDR_TYPE (type), ind_levels, insn);
+ push_reg_equiv_alt_mem (regno, tem, orig);
}
/* We can avoid a reload if the register's equivalent memory
expression is valid as an indirect memory address.
@@ -5545,6 +5569,8 @@ find_reloads_address_1 (enum machine_mod
if (reg_equiv_address[regno]
|| ! rtx_equal_p (tem, reg_equiv_mem[regno]))
{
+ rtx orig = tem;
+
/* First reload the memory location's address.
We can't use ADDR_TYPE (type) here, because we need to
write back the value after reading it, hence we actually
@@ -5554,6 +5580,8 @@ find_reloads_address_1 (enum machine_mod
RELOAD_OTHER,
ind_levels, insn);
+ push_reg_equiv_alt_mem (regno, tem, orig);
+
/* Then reload the memory location into a base
register. */
reloadnum = push_reload (tem, tem, &XEXP (x, 0),
@@ -5609,6 +5637,8 @@ find_reloads_address_1 (enum machine_mod
if (reg_equiv_address[regno]
|| ! rtx_equal_p (tem, reg_equiv_mem[regno]))
{
+ rtx orig = tem;
+
/* First reload the memory location's address.
We can't use ADDR_TYPE (type) here, because we need to
write back the value after reading it, hence we actually
@@ -5616,6 +5646,7 @@ find_reloads_address_1 (enum machine_mod
find_reloads_address (GET_MODE (tem), &tem, XEXP (tem, 0),
&XEXP (tem, 0), opnum, type,
ind_levels, insn);
+ push_reg_equiv_alt_mem (regno, tem, orig);
/* Put this inside a new increment-expression. */
x = gen_rtx_fmt_e (GET_CODE (x), GET_MODE (x), tem);
/* Proceed to reload that, as if it contained a register. */
@@ -5806,6 +5837,7 @@ find_reloads_address_1 (enum machine_mod
find_reloads_address (GET_MODE (x), &x, XEXP (x, 0),
&XEXP (x, 0), opnum, ADDR_TYPE (type),
ind_levels, insn);
+ push_reg_equiv_alt_mem (regno, x, tem);
}
}
@@ -5993,6 +6025,7 @@ find_reloads_subreg_address (rtx x, int
unsigned outer_size = GET_MODE_SIZE (GET_MODE (x));
unsigned inner_size = GET_MODE_SIZE (GET_MODE (SUBREG_REG (x)));
int offset;
+ rtx orig = tem;
/* For big-endian paradoxical subregs, SUBREG_BYTE does not
hold the correct (negative) byte offset. */
@@ -6028,6 +6061,9 @@ find_reloads_subreg_address (rtx x, int
find_reloads_address (GET_MODE (tem), &tem, XEXP (tem, 0),
&XEXP (tem, 0), opnum, type,
ind_levels, insn);
+ /* ??? Do we need to handle nonzero offsets somehow? */
+ if (!offset)
+ push_reg_equiv_alt_mem (regno, tem, orig);
/* If this is not a toplevel operand, find_reloads doesn't see
this substitution. We have to emit a USE of the pseudo so
Index: gcc/reload.h
===================================================================
--- gcc/reload.h.orig 2006-08-15 07:01:19.000000000 -0300
+++ gcc/reload.h 2006-08-16 05:44:44.000000000 -0300
@@ -161,6 +161,7 @@ extern rtx *reg_equiv_invariant;
extern rtx *reg_equiv_memory_loc;
extern rtx *reg_equiv_address;
extern rtx *reg_equiv_mem;
+extern rtx *reg_equiv_alt_mem_list;
/* Element N is the list of insns that initialized reg N from its equivalent
constant or memory slot. */
--
Alexandre Oliva http://www.lsd.ic.unicamp.br/~oliva/
Secretary for FSF Latin America http://www.fsfla.org/
Red Hat Compiler Engineer aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist oliva@{lsd.ic.unicamp.br, gnu.org}