From 4f864166ddda1be2c0d715a84c237c3449883b41 Mon Sep 17 00:00:00 2001
From: Sanjay Patel <spatel@rotateright.com>
Date: Fri, 13 May 2016 17:28:12 +0000
Subject: [PATCH] [InstCombine] handle zero constant vectors for LE/GE
 comparisons too

Enhancement to: http://reviews.llvm.org/rL269426
With discussion in: http://reviews.llvm.org/D17859

This should complete the fixes for: PR26701, PR26819:
https://llvm.org/bugs/show_bug.cgi?id=26701
https://llvm.org/bugs/show_bug.cgi?id=26819



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@269439 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/InstCombine/InstCombineCompares.cpp |  5 +--
 test/Transforms/InstCombine/icmp-vec.ll            | 37 ++++++++++++++++++++++
 2 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/lib/Transforms/InstCombine/InstCombineCompares.cpp b/lib/Transforms/InstCombine/InstCombineCompares.cpp
index acc03e722f0..e06ec3945e3 100644
--- a/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3130,8 +3130,9 @@ static ICmpInst *canonicalizeCmpWithConstant(ICmpInst &I,
   }
 
   // The usual vector types are ConstantDataVector. Exotic vector types are
-  // ConstantVector. They both derive from Constant.
-  if (isa<ConstantDataVector>(Op1) || isa<ConstantVector>(Op1)) {
+  // ConstantVector. Zeros are special. They all derive from Constant.
+  if (isa<ConstantDataVector>(Op1) || isa<ConstantVector>(Op1) ||
+      isa<ConstantAggregateZero>(Op1)) {
     Constant *Op1C = cast<Constant>(Op1);
     Type *Op1Type = Op1->getType();
     unsigned NumElts = Op1Type->getVectorNumElements();
diff --git a/test/Transforms/InstCombine/icmp-vec.ll b/test/Transforms/InstCombine/icmp-vec.ll
index f8416cc6e95..df653caa56d 100644
--- a/test/Transforms/InstCombine/icmp-vec.ll
+++ b/test/Transforms/InstCombine/icmp-vec.ll
@@ -42,6 +42,43 @@ define <2 x i1> @ule(<2 x i8> %x) {
   ret <2 x i1> %cmp
 }
 
+; Zeros are special: they're ConstantAggregateZero.
+
+define <2 x i1> @sge_zero(<2 x i8> %x) {
+; CHECK-LABEL: @sge_zero(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp sgt <2 x i8> %x, <i8 -1, i8 -1>
+; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+;
+  %cmp = icmp sge <2 x i8> %x, <i8 0, i8 0>
+  ret <2 x i1> %cmp
+}
+
+define <2 x i1> @uge_zero(<2 x i8> %x) {
+; CHECK-LABEL: @uge_zero(
+; CHECK-NEXT:    ret <2 x i1> <i1 true, i1 true>
+;
+  %cmp = icmp uge <2 x i8> %x, <i8 0, i8 0>
+  ret <2 x i1> %cmp
+}
+
+define <2 x i1> @sle_zero(<2 x i8> %x) {
+; CHECK-LABEL: @sle_zero(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp slt <2 x i8> %x, <i8 1, i8 1>
+; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+;
+  %cmp = icmp sle <2 x i8> %x, <i8 0, i8 0>
+  ret <2 x i1> %cmp
+}
+
+define <2 x i1> @ule_zero(<2 x i8> %x) {
+; CHECK-LABEL: @ule_zero(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp ult <2 x i8> %x, <i8 1, i8 1>
+; CHECK-NEXT:    ret <2 x i1> [[CMP]]
+;
+  %cmp = icmp ule <2 x i8> %x, <i8 0, i8 0>
+  ret <2 x i1> %cmp
+}
+
 ; Weird types are ConstantVectors, not ConstantDataVectors. For an i3 type:
 ; Signed min = -4
 ; Unsigned min = 0
-- 
2.11.0