Souper says:

; Function: fn2
%0:i32 = var 
%1:i32 = lshr 1:i32, %0
%2:i1 = slt 4294967295:i32, %1
cand %2 1:i1

COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_685/foo.bc

LLVM says:

define i32 @fn1(i32 %p1) #0 {
entry:
  %cmp = icmp sgt i32 %p1, -1
  %p1.lobit = lshr i32 %p1, 31
  %p1.lobit.not = xor i32 %p1.lobit, 1
  %conv. = select i1 %cmp, i32 %p1.lobit.not, i32 0
  ret i32 %conv.
}
define void @fn2() #1 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %shr = lshr i32 1, %0
  store i32 %shr, i32* @d, align 4, !tbaa !1
  store i32 %shr, i32* @c, align 4, !tbaa !1
  %cmp.i = icmp sgt i32 %shr, -1
  %p1.lobit.i = lshr i32 %shr, 31
  %p1.lobit.not.i = xor i32 %p1.lobit.i, 1
  %conv..i = select i1 %cmp.i, i32 %p1.lobit.not.i, i32 0
  store i32 %conv..i, i32* @b, align 4, !tbaa !1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_685/foo.c -o reduce_685/foo.bc

C source code:

int a, b, c, d;
int fn1(p1) { return p1 >= 0 ?: 0; }

void fn2() {
  int *e = &c;
  d = 1 >> a;
  c = d;
  b = fn1(*e);
}

x86-64 from LLVM:

fn1:                                    # @fn1
	movl	%edi, %ecx
	shrl	$31, %ecx
	xorl	$1, %ecx
	xorl	%eax, %eax
	testl	%edi, %edi
	cmovnsl	%ecx, %eax
	retq
fn2:                                    # @fn2
	movb	a(%rip), %cl
	movl	$1, %eax
	shrl	%cl, %eax
	movl	%eax, %ecx
	shrl	$31, %ecx
	xorl	$1, %ecx
	xorl	%edx, %edx
	testl	%eax, %eax
	movl	%eax, d(%rip)
	movl	%eax, c(%rip)
	cmovnsl	%ecx, %edx
	movl	%edx, b(%rip)
	retq
.Ltmp1:

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_685/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	%edi, %eax
	notl	%eax
	shrl	$31, %eax
	ret
fn2:
.LFB1:
	movl	a(%rip), %ecx
	movl	$1, %eax
	sarl	%cl, %eax
	movl	%eax, d(%rip)
	movl	%eax, c(%rip)
	notl	%eax
	shrl	$31, %eax
	movl	%eax, b(%rip)
	ret
.LFE1:

COMMAND: gcc -w -O3 reduce_685/foo.c -S -o -