Souper says:

; Function: fn1
%0:i32 = var 
%1:i1 = eq 0:i32, %0
%2:i32 = zext %1
%3:i32 = var 
%4:i1 = ne 0:i32, %3
%5:i32 = zext %4
%6:i32 = subnsw %2, %5
%7:i1 = slt %6, 2:i32
cand %7 1:i1

COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_307/foo.bc

LLVM says:

define void @fn1() #0 {
entry:
  %0 = load i32* @c, align 4, !tbaa !1
  %cmp = icmp eq i32 %0, 0
  %conv = zext i1 %cmp to i32
  %1 = load i32* @b, align 4, !tbaa !1
  %cmp1 = icmp ne i32 %1, 0
  %conv2 = zext i1 %cmp1 to i32
  %sub = sub nsw i32 %conv, %conv2
  %cmp3 = icmp slt i32 %sub, 2
  %conv4 = zext i1 %cmp3 to i32
  store i32 %conv4, i32* @a, align 4, !tbaa !1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_307/foo.c -o reduce_307/foo.bc

C source code:

int a, b, c;
void fn1() { a = (0 == c) - (b != 0) <= 1; }

x86-64 from LLVM:

fn1:                                    # @fn1
	cmpl	$0, c(%rip)
	sete	%al
	movzbl	%al, %eax
	cmpl	$1, b(%rip)
	adcl	$-1, %eax
	cmpl	$2, %eax
	setl	%al
	movzbl	%al, %eax
	movl	%eax, a(%rip)
	retq

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_307/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	$1, a(%rip)
	ret

COMMAND: gcc -w -O3 reduce_307/foo.c -S -o -