Souper says:

; Function: fn1
%0:i32 = var 
%1:i32 = or 5529:i32, %0
%2:i1 = var 
%3:i32 = select %2, 0:i32, 4294967283:i32
%4:i1 = eq %1, %3
cand %4 0:i1

COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_435/foo.bc

LLVM says:

define void @fn1() #0 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %or = or i32 %0, 5529
  %.b = load i1* @b, align 1
  %add = select i1 %.b, i32 0, i32 -13
  %tobool = icmp eq i32 %or, %add
  br i1 %tobool, label %if.end, label %if.then

if.then:                                          ; preds = %entry
  store i1 true, i1* @b, align 1
  br label %if.end

if.end:                                           ; preds = %entry, %if.then
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_435/foo.c -o reduce_435/foo.bc

C source code:

int a;
static int b = 13;
void fn1() {
  if ((a | 5529) + b)
    b = 0;
}

x86-64 from LLVM:

fn1:                                    # @fn1
	movl	$5529, %eax             # imm = 0x1599
	orl	a(%rip), %eax
	movb	b(%rip), %cl
	xorl	%edx, %edx
	testb	%cl, %cl
	movl	$-13, %ecx
	cmovnel	%edx, %ecx
	cmpl	%ecx, %eax
	je	.LBB0_2
	movb	$1, b(%rip)
.LBB0_2:                                # %if.end
	retq

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_435/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	a(%rip), %eax
	orl	$5529, %eax
	addl	b(%rip), %eax
	testl	%eax, %eax
	je	.L1
	movl	$0, b(%rip)
.L1:
	rep ret
b:

COMMAND: gcc -w -O3 reduce_435/foo.c -S -o -