Souper says:

; Function: fn1
%0:i32 = var 
%1:i1 = slt 0:i32, %0
%2:i32 = sext %1
%3:i32 = var 
%4:i1 = eq 0:i32, %3
%5:i32 = zext %4
%6:i1 = sle %2, %5
cand %6 1:i1

COMMAND: /home/regehr/souper/build/souper -stp-path=/usr/local/bin/stp reduce_66/foo.bc

LLVM says:

define void @fn1() #0 {
entry:
  %0 = load i32* @a, align 4, !tbaa !1
  %cmp = icmp sgt i32 %0, 0
  %conv = zext i1 %cmp to i32
  store i32 %conv, i32* @d, align 4, !tbaa !1
  %sub = sext i1 %cmp to i32
  store i32 %sub, i32* @e, align 4, !tbaa !1
  %1 = load i32* @b, align 4, !tbaa !1
  %cmp1 = icmp eq i32 %1, 0
  %conv2 = zext i1 %cmp1 to i32
  %cmp3 = icmp sge i32 %conv2, %sub
  %conv4 = zext i1 %cmp3 to i32
  store i32 %conv4, i32* @c, align 4, !tbaa !1
  ret void
}

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -c -w -emit-llvm -O3 reduce_66/foo.c -o reduce_66/foo.bc

C source code:

int a, b, c, d, e;
void fn1() {
  d = 0 < a;
  e = -d;
  c = (0 == b) >= e;
}

x86-64 from LLVM:

fn1:                                    # @fn1
	xorl	%eax, %eax
	cmpl	$0, a(%rip)
	setg	%cl
	movzbl	%cl, %ecx
	movl	%ecx, d(%rip)
	movl	$-1, %ecx
	cmovlel	%eax, %ecx
	movl	%ecx, e(%rip)
	cmpl	$0, b(%rip)
	sete	%al
	movzbl	%al, %eax
	cmpl	%ecx, %eax
	setge	%al
	movzbl	%al, %eax
	movl	%eax, c(%rip)
	retq

COMMAND: /home/regehr/souper/third_party/llvm/Debug/bin/clang -w -O3 reduce_66/foo.c -S -o -

x86-64 from GCC:

fn1:
	movl	a(%rip), %edx
	xorl	%eax, %eax
	movl	$1, c(%rip)
	testl	%edx, %edx
	setg	%al
	movl	%eax, d(%rip)
	negl	%eax
	movl	%eax, e(%rip)
	ret

COMMAND: gcc -w -O3 reduce_66/foo.c -S -o -