Souper says:

; Function: fn1
%0:i32 = var 
%1:i1 = ne 0:i32, %0
%2:i32 = zext %1
%3:i32 = or 12:i32, %2
%4:i32 = urem 4:i32, %3
%5:i1 = ne 0:i32, %4
cand %5 1:i1

COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_702/foo.bc

LLVM says:

define void @fn1() #0 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %tobool = icmp ne i32 %0, 0
  %lor.ext = zext i1 %tobool to i32
  %or = or i32 %lor.ext, 12
  %rem = urem i32 4, %or
  %tobool1 = icmp ne i32 %rem, 0
  %lor.ext4 = zext i1 %tobool1 to i32
  store i32 %lor.ext4, i32* @b, align 4, !tbaa !1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_702/foo.c -o reduce_702/foo.bc

C source code:

int a, b;
void fn1() { b = 4 % ((a || 0) | 12) || 0; }

x86-64 from LLVM:

fn1:                                    # @fn1
	cmpl	$0, a(%rip)
	setne	%al
	movzbl	%al, %ecx
	orl	$12, %ecx
	movl	$4, %eax
	xorl	%edx, %edx
	divl	%ecx
	testl	%edx, %edx
	setne	%al
	movzbl	%al, %eax
	movl	%eax, b(%rip)
	retq

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_702/foo.c -S -o -

x86-64 from GCC:

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

COMMAND: gcc -w -O3 reduce_702/foo.c -S -o -