From b844f35bcd7f92fc51dba9dddd202b4ed493b536 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@gmail.com>
Date: Mon, 17 Apr 2017 03:41:47 +0000
Subject: [PATCH] [InstCombine] Simplify 1/X for vectors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@300439 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstCombineMulDivRem.cpp           | 31 +++++++++++-----------
 test/Transforms/InstCombine/div.ll                 |  7 +++--
 2 files changed, 20 insertions(+), 18 deletions(-)

diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 953e7f36467..2d93e80fc13 100644
--- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -944,22 +944,21 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
     }
   }
 
-  if (ConstantInt *One = dyn_cast<ConstantInt>(Op0)) {
-    if (One->isOne() && !I.getType()->isIntegerTy(1)) {
-      bool isSigned = I.getOpcode() == Instruction::SDiv;
-      if (isSigned) {
-        // If Op1 is 0 then it's undefined behaviour, if Op1 is 1 then the
-        // result is one, if Op1 is -1 then the result is minus one, otherwise
-        // it's zero.
-        Value *Inc = Builder->CreateAdd(Op1, One);
-        Value *Cmp = Builder->CreateICmpULT(
-                         Inc, ConstantInt::get(I.getType(), 3));
-        return SelectInst::Create(Cmp, Op1, ConstantInt::get(I.getType(), 0));
-      } else {
-        // If Op1 is 0 then it's undefined behaviour. If Op1 is 1 then the
-        // result is one, otherwise it's zero.
-        return new ZExtInst(Builder->CreateICmpEQ(Op1, One), I.getType());
-      }
+  if (match(Op0, m_One())) {
+    assert(!I.getType()->getScalarType()->isIntegerTy(1) &&
+           "i1 divide not removed?");
+    if (I.getOpcode() == Instruction::SDiv) {
+      // If Op1 is 0 then it's undefined behaviour, if Op1 is 1 then the
+      // result is one, if Op1 is -1 then the result is minus one, otherwise
+      // it's zero.
+      Value *Inc = Builder->CreateAdd(Op1, Op0);
+      Value *Cmp = Builder->CreateICmpULT(
+                       Inc, ConstantInt::get(I.getType(), 3));
+      return SelectInst::Create(Cmp, Op1, ConstantInt::get(I.getType(), 0));
+    } else {
+      // If Op1 is 0 then it's undefined behaviour. If Op1 is 1 then the
+      // result is one, otherwise it's zero.
+      return new ZExtInst(Builder->CreateICmpEQ(Op1, Op0), I.getType());
     }
   }
 
diff --git a/test/Transforms/InstCombine/div.ll b/test/Transforms/InstCombine/div.ll
index ab72f2cc5f5..796fce020fd 100644
--- a/test/Transforms/InstCombine/div.ll
+++ b/test/Transforms/InstCombine/div.ll
@@ -227,7 +227,8 @@ define i32 @test19(i32 %x) {
 
 define <2 x i32> @test19vec(<2 x i32> %x) {
 ; CHECK-LABEL: @test19vec(
-; CHECK-NEXT:    [[A:%.*]] = udiv <2 x i32> <i32 1, i32 1>, [[X:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq <2 x i32> [[X:%.*]], <i32 1, i32 1>
+; CHECK-NEXT:    [[A:%.*]] = zext <2 x i1> [[TMP1]] to <2 x i32>
 ; CHECK-NEXT:    ret <2 x i32> [[A]]
 ;
   %A = udiv <2 x i32> <i32 1, i32 1>, %x
@@ -247,7 +248,9 @@ define i32 @test20(i32 %x) {
 
 define <2 x i32> @test20vec(<2 x i32> %x) {
 ; CHECK-LABEL: @test20vec(
-; CHECK-NEXT:    [[A:%.*]] = sdiv <2 x i32> <i32 1, i32 1>, [[X:%.*]]
+; CHECK-NEXT:    [[TMP1:%.*]] = add <2 x i32> [[X:%.*]], <i32 1, i32 1>
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp ult <2 x i32> [[TMP1]], <i32 3, i32 3>
+; CHECK-NEXT:    [[A:%.*]] = select <2 x i1> [[TMP2]], <2 x i32> [[X]], <2 x i32> zeroinitializer
 ; CHECK-NEXT:    ret <2 x i32> [[A]]
 ;
   %A = sdiv <2 x i32> <i32 1, i32 1>, %x
-- 
2.11.0