https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80491
Paul Zimmermann <zimmerma+gcc at loria dot fr> changed:
What |Removed |Added
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CC| |zimmerma+gcc at loria dot fr
--- Comment #15 from Paul Zimmermann <zimmerma+gcc at loria dot fr> ---
I just checked with gcc 9.2.1 20191109 (Debian 9.2.1-19) and it seems -O1
produces better code than -O3. Is there a non-regression test?
$ gcc -S -O3 test.cc -o-
.file "test.cc"
.text
.p2align 4
.globl _Z3addR4pairS0_
.type _Z3addR4pairS0_, @function
_Z3addR4pairS0_:
.LFB0:
.cfi_startproc
movq (%rsi), %rax
xorl %ecx, %ecx
addq (%rdi), %rax
setc %cl
movq 8(%rsi), %rdx
addq 8(%rdi), %rdx
addq %rcx, %rdx
ret
.cfi_endproc
.LFE0:
.size _Z3addR4pairS0_, .-_Z3addR4pairS0_
.ident "GCC: (Debian 9.2.1-19) 9.2.1 20191109"
.section .note.GNU-stack,"",@progbits
$ gcc -S -O1 test.cc -o-
.file "test.cc"
.text
.globl _Z3addR4pairS0_
.type _Z3addR4pairS0_, @function
_Z3addR4pairS0_:
.LFB0:
.cfi_startproc
movq (%rdi), %rax
movq 8(%rsi), %rdx
addq (%rsi), %rax
adcq 8(%rdi), %rdx
ret
.cfi_endproc
.LFE0:
.size _Z3addR4pairS0_, .-_Z3addR4pairS0_
.ident "GCC: (Debian 9.2.1-19) 9.2.1 20191109"
.section .note.GNU-stack,"",@progbits
