https://bugs.llvm.org/show_bug.cgi?id=43428
Bug ID: 43428
Summary: Missed optimization: int range info isn't used
Product: clang
Version: unspecified
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: LLVM Codegen
Assignee: unassignedclangb...@nondot.org
Reporter: zamazan...@tut.by
CC: llvm-bugs@lists.llvm.org, neeil...@live.com,
richard-l...@metafoo.co.uk
For the following code:
unsigned sample(unsigned m ){
if(m >= 10) return 42;
return m / 10;
}
clang(trunk) with '-O3' generates this:
sample(unsigned int): # @sample(unsigned int)
mov eax, 42
cmp edi, 9
ja .LBB0_2
mov ecx, edi
mov eax, 3435973837
imul rax, rcx
shr rax, 35
.LBB0_2:
ret
but gcc(trunk) with 'O3' optimizes more and generates this:
sample(unsigned int):
cmp edi, 10
sbb eax, eax
not eax
and eax, 42
ret
Godbolt playground: https://godbolt.org/z/Q-EaVW
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
llvm-bugs@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
