Souper says:

; Function: fn2
%0:i32 = var 
%1:i1 = ne 0:i32, %0
%2:i32 = zext %1
%3:i32 = lshr 5: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_621/foo.bc

LLVM says:

define i32 @fn1(i32 %p1) #0 {
entry:
  %shr = lshr i32 5, %p1
  %tobool = icmp ne i32 %shr, 0
  %shr. = select i1 %tobool, i32 %shr, i32 1
  ret i32 %shr.
}
define void @fn2() #1 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %tobool = icmp ne i32 %0, 0
  %lor.ext = zext i1 %tobool to i32
  %shr.i = lshr i32 5, %lor.ext
  %tobool.i = icmp ne i32 %shr.i, 0
  %shr..i = select i1 %tobool.i, i32 %shr.i, i32 1
  store i32 %shr..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_621/foo.c -o reduce_621/foo.bc

C source code:

int a, b;
int fn1(p1) { return 5 >> p1 ?: 1; }

void fn2() { b = fn1(0 || a); }

x86-64 from LLVM:

fn1:                                    # @fn1
	movl	$5, %edx
	movb	%dil, %cl
	shrl	%cl, %edx
	testl	%edx, %edx
	movl	$1, %eax
	cmovnel	%edx, %eax
	retq
fn2:                                    # @fn2
	cmpl	$0, a(%rip)
	setne	%cl
	movl	$5, %eax
	shrl	%cl, %eax
	testl	%eax, %eax
	movl	$1, %ecx
	cmovnel	%eax, %ecx
	movl	%ecx, b(%rip)
	retq
.Ltmp1:

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_621/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	%edi, %ecx
	movl	$5, %edx
	movl	$1, %eax
	sarl	%cl, %edx
	testl	%edx, %edx
	cmovne	%edx, %eax
	ret
fn2:
.LFB1:
	movl	a(%rip), %eax
	testl	%eax, %eax
	movl	$5, %eax
	setne	%cl
	sarl	%cl, %eax
	movl	%eax, b(%rip)
	ret
.LFE1:

COMMAND: gcc -w -O3 reduce_621/foo.c -S -o -