[Bug debug/104263] [10/11/12 Regression] '-fcompare-debug' failure (length) w/ -O2 -fnon-call-exceptions -fno-inline-small-functions
rguenth at gcc dot gnu.org
gcc-bugzilla@gcc.gnu.org
Fri Jan 28 08:16:25 GMT 2022
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104263
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Target Milestone|--- |10.4
Ever confirmed|0 |1
Last reconfirmed| |2022-01-28
Priority|P3 |P2
Status|UNCONFIRMED |NEW
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed. Caused by store-merging:
-Coalescing successful!
-Merged into 1 stores
-New sequence of 1 stores to replace old one of 2 stores
-Merging successful!
__attribute__((returns_twice, pure))
int foo ()
{
<bb 2> [local count: 1073741824]:
+ # DEBUG BEGIN_STMT
+ # DEBUG INLINE_ENTRY bar
+ # DEBUG BEGIN_STMT
+ # DEBUG BEGIN_STMT
+ n = 0;
+ # DEBUG BEGIN_STMT
+ # DEBUG a => 0
+ # DEBUG BEGIN_STMT
<bb 3> [local count: 1073312329]:
- MEM[(int *)&n] = 1;
+ n = 1;
+ # DEBUG BEGIN_STMT
<bb 4> [local count: 1073741824]:
+ # DEBUG BEGIN_STMT
return 0;
<bb 5> [local count: 429496]:
so we fail to merge n = 0 and n = 1 with -g.
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