Souper says:
; Function: fn1
%0:i32 = var
%1:i32 = subnsw 0:i32, %0
%2:i32 = and %0, %1
%3:i1 = slt %2, 4294967294:i32
cand %3 0:i1
COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_427/foo.bc
LLVM says:
define void @fn1() #0 {
entry:
%0 = load i32* @a, align 4, !tbaa !1
%sub = sub nsw i32 0, %0
%and = and i32 %0, %sub
store i32 %and, i32* @c, align 4, !tbaa !1
%cmp = icmp slt i32 %and, -2
%conv1 = zext i1 %cmp to i32
store i32 %conv1, i32* @b, align 4, !tbaa !1
ret void
}
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_427/foo.c -o reduce_427/foo.bc
C source code:
int a, b, c;
void fn1() {
c = a & -a;
b = c <= -3L;
}
x86-64 from LLVM:
fn1: # @fn1
movl a(%rip), %eax
movl %eax, %ecx
negl %ecx
andl %eax, %ecx
cmpl $-2, %ecx
movl %ecx, c(%rip)
setl %al
movzbl %al, %eax
movl %eax, b(%rip)
retq
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_427/foo.c -S -o -
x86-64 from GCC:
fn1:
movl a(%rip), %edx
movl %edx, %eax
negl %eax
andl %edx, %eax
cmpl $-2, %eax
movl %eax, c(%rip)
setl %al
movzbl %al, %eax
movl %eax, b(%rip)
ret
COMMAND: gcc -w -O3 reduce_427/foo.c -S -o -