[Bug ipa/99373] New: [missed optimization] dead code not eliminated from short circuiting
zhendong.su at inf dot ethz.ch
gcc-bugzilla@gcc.gnu.org
Wed Mar 3 23:11:23 GMT 2021
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99373
Bug ID: 99373
Summary: [missed optimization] dead code not eliminated from
short circuiting
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: ---
[538] % 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 20210303 (experimental) [master revision
d97a92dca90:bc15d73426f:9b2084db9f9917eb9b19b1eb5ec03cdcb05f349e] (GCC)
[539] %
[539] % gcctk -O3 -S -o small.s small.c
[540] %
[540] % cat small.c
extern void foo();
struct a {
int b;
long c;
} g;
static int d = 1;
int e, *f, *h;
long *i;
static long j() {
struct a k;
struct a *m = &g;
struct a **n[] = {&m};
long **l = 0;
int o[42];
foo();
int p[] = {1, 1, 1, 1, 1, 1, 1, 1, 1, 1};
int *d[] = {&p[3]};
i = &k.c;
long ***a[] = {&l};
int b[5];
f = &b[3];
if (e)
while (1)
h = &o[7];
return 0;
}
int main() {
d || j();
return 0;
}
[541] %
[541] % cat small.s
.file "small.c"
.text
.p2align 4
.type j.isra.0, @function
j.isra.0:
.LFB2:
.cfi_startproc
subq $56, %rsp
.cfi_def_cfa_offset 64
xorl %eax, %eax
call foo
leaq 8(%rsp), %rax
movq %rax, i(%rip)
leaq 28(%rsp), %rax
movq %rax, f(%rip)
movl e(%rip), %eax
testl %eax, %eax
jne .L3
addq $56, %rsp
.cfi_remember_state
.cfi_def_cfa_offset 8
ret
.L3:
.cfi_restore_state
jmp .L3
.cfi_endproc
.LFE2:
.size j.isra.0, .-j.isra.0
.section .text.startup,"ax",@progbits
.p2align 4
.globl main
.type main, @function
main:
.LFB1:
.cfi_startproc
xorl %eax, %eax
ret
.cfi_endproc
.LFE1:
.size main, .-main
.globl i
.bss
.align 8
.type i, @object
.size i, 8
i:
.zero 8
.globl h
.align 8
.type h, @object
.size h, 8
h:
.zero 8
.globl f
.align 8
.type f, @object
.size f, 8
f:
.zero 8
.globl e
.align 4
.type e, @object
.size e, 4
e:
.zero 4
.globl g
.align 16
.type g, @object
.size g, 16
g:
.zero 16
.ident "GCC: (GNU) 11.0.1 20210303 (experimental) [master revision
d97a92dca90:bc15d73426f:9b2084db9f9917eb9b19b1eb5ec03cdcb05f349e]"
.section .note.GNU-stack,"",@progbits
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