Souper says:
; Function: fn1
%0:i32 = var
%1:i32 = srem %0, 2:i32
%2:i16 = trunc %1
%3:i1 = slt 2:i16, %2
cand %3 0:i1
COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_574/foo.bc
LLVM says:
define void @fn1() #0 {
entry:
%0 = load i32* @a, align 4, !tbaa !1
%rem = srem i32 %0, 2
%conv = trunc i32 %rem to i16
store i16 %conv, i16* @b, align 2, !tbaa !5
%cmp = icmp sgt i16 %conv, 2
br i1 %cmp, label %for.cond.preheader, label %for.end.split
for.cond.preheader: ; preds = %entry
br label %for.cond
for.cond: ; preds = %for.cond.preheader, %for.cond
br label %for.cond
for.end.split: ; preds = %entry
ret void
}
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_574/foo.c -o reduce_574/foo.bc
C source code:
int a;
short b;
void fn1() {
b = a % 2;
for (; b >= 3;)
;
}
x86-64 from LLVM:
fn1: # @fn1
movl a(%rip), %eax
movl %eax, %ecx
shrl $31, %ecx
addl %eax, %ecx
andl $65534, %ecx # imm = 0xFFFE
subl %ecx, %eax
cwtl
cmpl $3, %eax
movw %ax, b(%rip)
jl .LBB0_2
.LBB0_1: # %for.cond
jmp .LBB0_1
.LBB0_2: # %for.end.split
retq
COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_574/foo.c -S -o -
x86-64 from GCC:
fn1:
movl a(%rip), %eax
movl %eax, %edx
shrl $31, %edx
addl %edx, %eax
andl $1, %eax
subl %edx, %eax
movw %ax, b(%rip)
ret
COMMAND: gcc -w -O3 reduce_574/foo.c -S -o -