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* [Bug ipa/100036] New: missed optimization for dead code elimination at -Os, -O2 and -O3 (vs. -O1)
@ 2021-04-11 15:56 zhendong.su at inf dot ethz.ch
2021-04-12 8:56 ` [Bug ipa/100036] " rguenth at gcc dot gnu.org
2021-04-12 8:56 ` rguenth at gcc dot gnu.org
0 siblings, 2 replies; 3+ messages in thread
From: zhendong.su at inf dot ethz.ch @ 2021-04-11 15:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100036
Bug ID: 100036
Summary: missed optimization for dead code elimination at -Os,
-O2 and -O3 (vs. -O1)
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: ipa
Assignee: unassigned at gcc dot gnu.org
Reporter: zhendong.su at inf dot ethz.ch
CC: marxin at gcc dot gnu.org
Target Milestone: ---
[562] % gcctk -v
Using built-in specs.
COLLECT_GCC=gcctk
COLLECT_LTO_WRAPPER=/local/suz-local/software/local/gcc-trunk/libexec/gcc/x86_64-pc-linux-gnu/11.0.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-trunk/configure --disable-bootstrap
--prefix=/local/suz-local/software/local/gcc-trunk --enable-languages=c,c++
--disable-werror --enable-multilib --with-system-zlib
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 11.0.1 20210411 (experimental) [master revision
1d54b138417:e83b9cf4549:936d500dfc17f58f2507ecd0f7f26e4f197052ee] (GCC)
[563] %
[563] % gcctk -O1 -S -o O1.s small.c
[564] % gcctk -O3 -S -o O3.s small.c
[565] %
[565] % wc O1.s O3.s
27 58 454 O1.s
38 77 665 O3.s
65 135 1119 total
[566] %
[566] % grep foo O1.s
[567] % grep foo O3.s
jmp foo
[568] %
[568] % cat small.c
extern void foo(void);
int a, *b;
static int c, f;
inline int *d() {
int g[100] = {0};
if (a) {
int h = g[0];
foo();
return b;
}
}
int main() {
while (1) {
if (!c)
return f;
d();
}
return 0;
}
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug ipa/100036] missed optimization for dead code elimination at -Os, -O2 and -O3 (vs. -O1)
2021-04-11 15:56 [Bug ipa/100036] New: missed optimization for dead code elimination at -Os, -O2 and -O3 (vs. -O1) zhendong.su at inf dot ethz.ch
@ 2021-04-12 8:56 ` rguenth at gcc dot gnu.org
2021-04-12 8:56 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-04-12 8:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100036
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Version|unknown |11.0
Depends on| |99991
Keywords| |missed-optimization
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
And again, missing late dead function removal of an IPA SRA clone not inlined
at -O3.
Referenced Bugs:
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99991
[Bug 99991] Missed inlining of IPA SRA clone
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug ipa/100036] missed optimization for dead code elimination at -Os, -O2 and -O3 (vs. -O1)
2021-04-11 15:56 [Bug ipa/100036] New: missed optimization for dead code elimination at -Os, -O2 and -O3 (vs. -O1) zhendong.su at inf dot ethz.ch
2021-04-12 8:56 ` [Bug ipa/100036] " rguenth at gcc dot gnu.org
@ 2021-04-12 8:56 ` rguenth at gcc dot gnu.org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2021-04-12 8:56 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100036
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Ever confirmed|0 |1
Last reconfirmed| |2021-04-12
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-04-11 15:56 [Bug ipa/100036] New: missed optimization for dead code elimination at -Os, -O2 and -O3 (vs. -O1) zhendong.su at inf dot ethz.ch
2021-04-12 8:56 ` [Bug ipa/100036] " rguenth at gcc dot gnu.org
2021-04-12 8:56 ` rguenth at gcc dot gnu.org
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