Souper says:
; Function: fn2
%0:i32 = var
%1:i1 = ne 0:i32, %0
%2:i32 = zext %1
%3:i32 = lshr 5:i32, %2
%4:i1 = ne 0:i32, %3
cand %4 1:i1
COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_621/foo.bc
LLVM says:
define i32 @fn1(i32 %p1) #0 {
entry:
%shr = lshr i32 5, %p1
%tobool = icmp ne i32 %shr, 0
%shr. = select i1 %tobool, i32 %shr, i32 1
ret i32 %shr.
}
define void @fn2() #1 {
entry:
%0 = load i32* @a, align 4, !tbaa !1
%tobool = icmp ne i32 %0, 0
%lor.ext = zext i1 %tobool to i32
%shr.i = lshr i32 5, %lor.ext
%tobool.i = icmp ne i32 %shr.i, 0
%shr..i = select i1 %tobool.i, i32 %shr.i, i32 1
store i32 %shr..i, i32* @b, align 4, !tbaa !1
ret void
}
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_621/foo.c -o reduce_621/foo.bc
C source code:
int a, b;
int fn1(p1) { return 5 >> p1 ?: 1; }
void fn2() { b = fn1(0 || a); }
x86-64 from LLVM:
fn1: # @fn1
movl $5, %edx
movb %dil, %cl
shrl %cl, %edx
testl %edx, %edx
movl $1, %eax
cmovnel %edx, %eax
retq
fn2: # @fn2
cmpl $0, a(%rip)
setne %cl
movl $5, %eax
shrl %cl, %eax
testl %eax, %eax
movl $1, %ecx
cmovnel %eax, %ecx
movl %ecx, b(%rip)
retq
.Ltmp1:
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_621/foo.c -S -o -
x86-64 from GCC:
fn1:
movl %edi, %ecx
movl $5, %edx
movl $1, %eax
sarl %cl, %edx
testl %edx, %edx
cmovne %edx, %eax
ret
fn2:
.LFB1:
movl a(%rip), %eax
testl %eax, %eax
movl $5, %eax
setne %cl
sarl %cl, %eax
movl %eax, b(%rip)
ret
.LFE1:
COMMAND: gcc -w -O3 reduce_621/foo.c -S -o -