Souper says:

; Function: fn1
%0:i32 = var 
%1:i32 = lshr %0, 31:i32
%2:i32 = xor 1:i32, %1
%3:i32 = udiv 2: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_540/foo.bc

LLVM says:

define void @fn1() #0 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %.lobit = lshr i32 %0, 31
  %.lobit.not = xor i32 %.lobit, 1
  %div = udiv i32 2, %.lobit.not
  %cmp1 = icmp ne i32 %div, 0
  %conv2 = zext i1 %cmp1 to i32
  store i32 %conv2, i32* @b, align 4, !tbaa !1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_540/foo.c -o reduce_540/foo.bc

C source code:

int a, b;
void fn1() { b = 2 / (a >= 0) >= 1; }

x86-64 from LLVM:

fn1:                                    # @fn1
	movl	a(%rip), %ecx
	shrl	$31, %ecx
	xorl	$1, %ecx
	movl	$2, %eax
	xorl	%edx, %edx
	divl	%ecx
	testl	%eax, %eax
	setne	%al
	movzbl	%al, %eax
	movl	%eax, b(%rip)
	retq

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_540/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	a(%rip), %edx
	movl	$1, %eax
	testl	%edx, %edx
	jns	.L2
	movb	$2, %al
	xorl	%ecx, %ecx
	cltd
	idivl	%ecx
	testl	%eax, %eax
	setne	%al
	movzbl	%al, %eax
.L2:
	movl	%eax, b(%rip)
	ret

COMMAND: gcc -w -O3 reduce_540/foo.c -S -o -