Souper says:

; Function: fn1
%0:i8 = var 
%1:i32 = zext %0
%2:i32 = var 
%3:i1 = ne 0:i32, %2
%4:i32 = sext %3
%5:i1 = slt %1, %4
cand %5 0:i1

COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_373/foo.bc

LLVM says:

define void @fn1() #0 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %not.cmp = icmp ne i32 %0, 0
  %sub = sext i1 %not.cmp to i32
  %1 = load i8* @b, align 1, !tbaa !5
  %conv1 = zext i8 %1 to i32
  %cmp2 = icmp sgt i32 %sub, %conv1
  %conv3 = zext i1 %cmp2 to i32
  store i32 %conv3, i32* @c, align 4, !tbaa !1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_373/foo.c -o reduce_373/foo.bc

C source code:

int a, c;
unsigned char b;
void fn1() { c = (0 == a) - 1 > b; }

x86-64 from LLVM:

fn1:                                    # @fn1
	xorl	%eax, %eax
	cmpl	a(%rip), %eax
	sbbl	%eax, %eax
	movzbl	b(%rip), %ecx
	cmpl	%ecx, %eax
	setg	%al
	movzbl	%al, %eax
	movl	%eax, c(%rip)
	retq

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_373/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	$0, c(%rip)
	ret

COMMAND: gcc -w -O3 reduce_373/foo.c -S -o -