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optabs: Fix up checking for CALLs in newly added code by double-word divmod [PR103838]

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These two spots are meant to punt if the newly added code contains
any CALL_INSNs, because in that case having a large sequence of insns
that also calls something is undesirable, better have one call that
is optimized in itself well.
The functions do last = get_last_insn (); before emitting any insns
(and expand_binop as the ultimate caller uses delete_insns_since if
the expansion fails), but the checks were incorrect for 2 reasons:
1) it checked not just what follows after that last insn, but also
   the last insn itself; so, if the division or modulo is immediately
   preceded by a CALL_INSN, then we punt; this also causes -fcompare-debug
   failures if the CALL_INSN is with -g followed by one or more DEBUG_INSNs
2) if get_last_insn () is NULL (i.e. emitting into a new sequence), then
   we didn't check anything

2021-12-28  Jakub Jelinek  <jakub@redhat.com>

	PR debug/103838
	* optabs.c (expand_doubleword_mod, expand_doubleword_divmod): Only
	check newly added insns for CALL_P, not the last insn of previous
	code.

	* gcc.dg/pr103838.c: New test.
This commit is contained in:
Jakub Jelinek 2021-12-28 17:39:23 +01:00
parent cff8fa9a44
commit 78ee8381bf
2 changed files with 36 additions and 0 deletions
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8
gcc/optabs.c
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@ -1135,6 +1135,10 @@ expand_doubleword_mod (machine_mode mode, rtx op0, rtx op1, bool unsignedp)
remainder = convert_modes (mode, word_mode, remainder, unsignedp);
/* Punt if we need any library calls. */
if (last)
last = NEXT_INSN (last);
else
last = get_insns ();
for (; last; last = NEXT_INSN (last))
if (CALL_P (last))
return NULL_RTX;
@ -1228,6 +1232,10 @@ expand_doubleword_divmod (machine_mode mode, rtx op0, rtx op1, rtx *rem,
}
/* Punt if we need any library calls. */
if (last)
last = NEXT_INSN (last);
else
last = get_insns ();
for (; last; last = NEXT_INSN (last))
if (CALL_P (last))
return NULL_RTX;

28
gcc/testsuite/gcc.dg/pr103838.c Normal file
View file

@ -0,0 +1,28 @@
/* PR debug/103838 */
/* { dg-do compile } */
/* { dg-options "-O2 -fcompare-debug" } */
#ifdef __SIZEOF_INT128__
__int128 m;
#else
long long m;
#endif
int n;
__attribute__((noinline)) void
bar (void)
{
n += !!m;
}
void
foo (void)
{
int i;
for (i = 0; i < 2; ++i)
{
bar ();
m /= 3;
}
}