Souper says:
; Function: fn1
%0:i32 = var
%1:i1 = slt %0, 0:i32
%2:i32 = lshr %0, 31:i32
%3:i32 = subnsw 0:i32, %0
%4:i32 = select %1, %2, %3
%5:i1 = eq 7:i32, %4
cand %5 0:i1
COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_139/foo.bc
LLVM says:
define void @fn1() #0 {
entry:
%0 = load i32* @a, align 4, !tbaa !1
%cmp = icmp slt i32 %0, 0
%.lobit = lshr i32 %0, 31
%sub = sub nsw i32 0, %0
%.lobit.sub = select i1 %cmp, i32 %.lobit, i32 %sub
store i32 %.lobit.sub, i32* @c, align 4, !tbaa !1
%cmp1 = icmp eq i32 %.lobit.sub, 7
%conv2 = zext i1 %cmp1 to i32
store i32 %conv2, i32* @b, align 4, !tbaa !1
ret void
}
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_139/foo.c -o reduce_139/foo.bc
C source code:
int a, b, c;
void fn1() {
c = a < 0 ?: -a;
b = c == 7;
}
x86-64 from LLVM:
fn1: # @fn1
movl a(%rip), %eax
movl %eax, %ecx
shrl $31, %ecx
movl %eax, %edx
negl %edx
testl %eax, %eax
cmovsl %ecx, %edx
cmpl $7, %edx
movl %edx, c(%rip)
sete %al
movzbl %al, %eax
movl %eax, b(%rip)
retq
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_139/foo.c -S -o -
x86-64 from GCC:
fn1:
movl a(%rip), %edx
movl $1, %eax
movl $0, b(%rip)
movl %edx, %ecx
negl %ecx
testl %edx, %edx
cmovns %ecx, %eax
movl %eax, c(%rip)
ret
COMMAND: gcc -w -O3 reduce_139/foo.c -S -o -