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ifcvt: Fix -fcompare-debug bug [PR100852]

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The following testcase fails -fcompare-debug, because it is ifcvt optimized
into umin only with -g0 and not with -g - the function(s) use
prev_nonnote_insn, which without -g finds a real insn the code is looking
for, while with -g finds a DEBUG_INSN.

2021-06-10  Jakub Jelinek  <jakub@redhat.com>

	PR debug/100852
	* ifcvt.c (noce_get_alt_condition, noce_try_abs): Use
	prev_nonnote_nondebug_insn instead of prev_nonnote_insn.

	* g++.dg/opt/pr100852.C: New test.
This commit is contained in:
Jakub Jelinek 2021-06-10 09:28:27 +02:00
parent f8b067056b
commit 2d2ed777b2
2 changed files with 27 additions and 2 deletions
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4
gcc/ifcvt.c
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@ -2398,7 +2398,7 @@ noce_get_alt_condition (struct noce_if_info *if_info, rtx target,
rtx_insn *prev_insn;
/* First, look to see if we put a constant in a register. */
prev_insn = prev_nonnote_insn (if_info->cond_earliest);
prev_insn = prev_nonnote_nondebug_insn (if_info->cond_earliest);
if (prev_insn
&& BLOCK_FOR_INSN (prev_insn)
== BLOCK_FOR_INSN (if_info->cond_earliest)
@ -2669,7 +2669,7 @@ noce_try_abs (struct noce_if_info *if_info)
if (REG_P (c))
{
rtx set;
rtx_insn *insn = prev_nonnote_insn (earliest);
rtx_insn *insn = prev_nonnote_nondebug_insn (earliest);
if (insn
&& BLOCK_FOR_INSN (insn) == BLOCK_FOR_INSN (earliest)
&& (set = single_set (insn))

25
gcc/testsuite/g++.dg/opt/pr100852.C Normal file
View File

@ -0,0 +1,25 @@
// PR debug/100852
// { dg-do compile }
// { dg-options "-Og -fif-conversion -fno-tree-ccp -fno-tree-copy-prop -fcompare-debug" }
static inline int
min (unsigned a, int b)
{
return a < b ? a : b;
}
struct S { S (char); };
static inline S
foo (unsigned x)
{
int h;
h += min (x * 4, h);
return h;
}
void
bar ()
{
foo (0);
}