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 -