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hardcmp: split before dispatch edge 

If we harden a compare at the end of a block with an edge to the
abnormal dispatch block, it won't have a single successor.  Arrange to
split the block at its final stmt so as to have a single succ.


for  gcc/ChangeLog

	PR middle-end/104975
	* gimple-harden-conditionals.cc
	(pass_harden_compares::execute): Force split in case of
	multiple edges.

for  gcc/testsuite/ChangeLog

	PR middle-end/104975
	* gcc.dg/pr104975.c: New.
This commit is contained in:
Alexandre Oliva 2022-03-24 10:02:27 -03:00 committed by Alexandre Oliva
parent 11fb784ac5
commit b8c4171ebd
2 changed files with 29 additions and 3 deletions
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12
gcc/gimple-harden-conditionals.cc
View File

@ -509,10 +509,16 @@ pass_harden_compares::execute (function *fun)
gsi_insert_before (&gsi_split, asgnck, GSI_SAME_STMT);
/* We wish to insert a cond_expr after the compare, so arrange
for it to be at the end of a block if it isn't. */
if (!gsi_end_p (gsi_split))
for it to be at the end of a block if it isn't, and for it
to have a single successor in case there's more than
one, as in PR104975. */
if (!gsi_end_p (gsi_split)
|| !single_succ_p (gsi_bb (gsi_split)))
{
gsi_prev (&gsi_split);
if (!gsi_end_p (gsi_split))
gsi_prev (&gsi_split);
else
gsi_split = gsi_last_bb (gsi_bb (gsi_split));
basic_block obb = gsi_bb (gsi_split);
basic_block nbb = split_block (obb, gsi_stmt (gsi_split))->dest;
gsi_next (&gsi_split);

20
gcc/testsuite/gcc.dg/pr104975.c Normal file
View File

@ -0,0 +1,20 @@
/* { dg-do compile } */
/* { dg-options "-O1 -fharden-compares -fno-inline -fno-ipa-pure-const" } */
__attribute__ ((pure, returns_twice)) int
bar (int);
int
quux (void)
{
return 0;
}
int
foo (short int x)
{
x = !x;
bar (quux ());
return x;
}