Souper says:

; Function: fn2
%0:i32 = var 
%1:i1 = eq 0:i32, %0
%2:i32 = var 
%3:i1 = eq 0:i32, %2
%4:i32 = zext %3
%5:i32 = xor %0, %4
%6:i1 = eq 8:i32, %5
%7:i1 = and %1, %6
cand %7 0:i1

COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_1/foo.bc

LLVM says:

define i32 @fn1(i32 %p1, i32 %p2) #0 {
entry:
  %cmp = icmp eq i32 %p1, 8
  %cmp1 = icmp eq i32 %p2, 0
  %cmp1. = and i1 %cmp, %cmp1
  %land.ext = zext i1 %cmp1. to i32
  ret i32 %land.ext
}
define void @fn2() #1 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %cmp = icmp eq i32 %0, 0
  %conv = zext i1 %cmp to i32
  store i32 %conv, i32* @c, align 4, !tbaa !1
  %1 = load i32* @b, align 4, !tbaa !1
  %xor = xor i32 %conv, %1
  %cmp.i = icmp eq i32 %xor, 8
  %cmp1.i = icmp eq i32 %1, 0
  %cmp1..i = and i1 %cmp.i, %cmp1.i
  %land.ext.i = zext i1 %cmp1..i to i32
  store i32 %land.ext.i, i32* @d, align 4, !tbaa !1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_1/foo.c -o reduce_1/foo.bc

C source code:

int a, b, c, d;
int fn1(p1, p2) { return p1 == 8 && p2 == 0; }

void fn2() {
  c = a == 0;
  d = fn1(c ^ b, b);
}

x86-64 from LLVM:

fn1:                                    # @fn1
	cmpl	$8, %edi
	sete	%al
	testl	%esi, %esi
	sete	%cl
	andb	%al, %cl
	movzbl	%cl, %eax
	retq
fn2:                                    # @fn2
	cmpl	$0, a(%rip)
	sete	%al
	movzbl	%al, %eax
	movl	%eax, c(%rip)
	movl	b(%rip), %ecx
	xorl	%ecx, %eax
	cmpl	$8, %eax
	sete	%al
	testl	%ecx, %ecx
	sete	%cl
	andb	%al, %cl
	movzbl	%cl, %eax
	movl	%eax, d(%rip)
	retq
.Ltmp1:

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_1/foo.c -S -o -

x86-64 from GCC:

fn1:
	cmpl	$8, %edi
	sete	%dl
	xorl	%eax, %eax
	testl	%esi, %esi
	sete	%al
	andl	%edx, %eax
	ret
fn2:
.LFB1:
	movl	a(%rip), %eax
	xorl	%edx, %edx
	testl	%eax, %eax
	movl	b(%rip), %eax
	sete	%dl
	movl	%edx, c(%rip)
	xorl	%eax, %edx
	cmpl	$8, %edx
	sete	%dl
	testl	%eax, %eax
	sete	%al
	movzbl	%al, %eax
	andl	%edx, %eax
	movl	%eax, d(%rip)
	ret
.LFE1:

COMMAND: gcc -w -O3 reduce_1/foo.c -S -o -