Souper says:

; Function: fn1
%0:i1 = var 
pc %0 1:i1
%1:i32 = zext %0
%2:i32 = xor 1:i32, %1
%3:i32 = lshr 1: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_624/foo.bc

LLVM says:

define void @fn1() #0 {
entry:
  %.b2 = load i1* @a, align 1
  %0 = zext i1 %.b2 to i32
  %1 = xor i32 %0, 1
  store i32 %1, i32* @b, align 4, !tbaa !1
  br i1 %.b2, label %lor.rhs, label %lor.end

lor.rhs:                                          ; preds = %entry
  %shr = lshr i32 1, %1
  %tobool1 = icmp ne i32 %shr, 0
  br label %lor.end

lor.end:                                          ; preds = %entry, %lor.rhs
  %2 = phi i1 [ true, %entry ], [ %tobool1, %lor.rhs ]
  %lor.ext = zext i1 %2 to i32
  store i32 %lor.ext, i32* @c, align 4, !tbaa !1
  store i1 true, i1* @a, align 1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_624/foo.c -o reduce_624/foo.bc

C source code:

static int a = 1;
int b;
int c;
void fn1() {
  b = a;
  c = a || 1 >> a;
  a = 0;
}

x86-64 from LLVM:

fn1:                                    # @fn1
	movzbl	a(%rip), %eax
	movl	%eax, %ecx
	xorl	$1, %ecx
	cmpl	$1, %eax
	movl	%ecx, b(%rip)
	movb	$1, %al
	jne	.LBB0_2
	movl	$1, %eax
	shrl	%cl, %eax
	testl	%eax, %eax
	setne	%al
.LBB0_2:                                # %lor.end
	movzbl	%al, %eax
	movl	%eax, c(%rip)
	movb	$1, a(%rip)
	retq

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_624/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	a(%rip), %eax
	movl	$1, c(%rip)
	movl	$0, a(%rip)
	movl	%eax, b(%rip)
	ret
a:

COMMAND: gcc -w -O3 reduce_624/foo.c -S -o -