From 946e6ed8ac684741c0a5256d1a0b5667b32b236b Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@intel.com>
Date: Sun, 6 Aug 2017 06:28:41 +0000
Subject: [PATCH] [InstCombine] Support ~(c-X) --> X+(-c-1) and ~(X-c) -->
 (-c-1)-X for splat vectors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310195 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../InstCombine/InstCombineAndOrXor.cpp       | 39 ++++++++++++-------
 .../Transforms/InstCombine/vec_phi_extract.ll |  2 +-
 test/Transforms/InstCombine/xor.ll            | 30 ++++++++++++++
 3 files changed, 56 insertions(+), 15 deletions(-)

diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 7b32812a2c1..e684f58f0f4 100644
--- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2419,17 +2419,33 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
     return replaceInstUsesWith(I, Op0);
   }
 
+  {
+    const APInt *RHSC;
+    if (match(Op1, m_APInt(RHSC))) {
+      Value *V;
+      const APInt *C;
+      if (match(Op0, m_Sub(m_APInt(C), m_Value(V)))) {
+        // ~(c-X) == X-c-1 == X+(-c-1)
+        if (RHSC->isAllOnesValue()) {
+          Constant *NewC = ConstantInt::get(I.getType(), -(*C) - 1);
+          return BinaryOperator::CreateAdd(V, NewC);
+        }
+      } else if (match(Op0, m_Add(m_Value(V), m_APInt(C)))) {
+        // ~(X-c) --> (-c-1)-X
+        if (RHSC->isAllOnesValue()) {
+          Constant *NewC = ConstantInt::get(I.getType(), -(*C) - 1);
+          return BinaryOperator::CreateSub(NewC, V);
+        }
+      }
+    }
+  }
+
   if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1)) {
     if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
-      // ~(c-X) == X-c-1 == X+(-c-1)
       if (Op0I->getOpcode() == Instruction::Sub)
         if (ConstantInt *Op0I0C = dyn_cast<ConstantInt>(Op0I->getOperand(0))) {
-          if (RHSC->isMinusOne()) {
-            Constant *NegOp0I0C = ConstantExpr::getNeg(Op0I0C);
-            return BinaryOperator::CreateAdd(Op0I->getOperand(1),
-                                             SubOne(NegOp0I0C));
-          } else if (RHSC->getValue().isSignMask()) {
-            // (C - X) ^ signmask -> (C + signmask - X)
+          // (C - X) ^ signmask -> (C + signmask - X)
+          if (RHSC->getValue().isSignMask()) {
             Constant *C = Builder.getInt(RHSC->getValue() + Op0I0C->getValue());
             return BinaryOperator::CreateSub(C, Op0I->getOperand(1));
           }
@@ -2437,13 +2453,8 @@ Instruction *InstCombiner::visitXor(BinaryOperator &I) {
 
       if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
         if (Op0I->getOpcode() == Instruction::Add) {
-          // ~(X-c) --> (-c-1)-X
-          if (RHSC->isMinusOne()) {
-            Constant *NegOp0CI = ConstantExpr::getNeg(Op0CI);
-            return BinaryOperator::CreateSub(SubOne(NegOp0CI),
-                                             Op0I->getOperand(0));
-          } else if (RHSC->getValue().isSignMask()) {
-            // (X + C) ^ signmask -> (X + C + signmask)
+          // (X + C) ^ signmask -> (X + C + signmask)
+          if (RHSC->getValue().isSignMask()) {
             Constant *C = Builder.getInt(RHSC->getValue() + Op0CI->getValue());
             return BinaryOperator::CreateAdd(Op0I->getOperand(0), C);
           }
diff --git a/test/Transforms/InstCombine/vec_phi_extract.ll b/test/Transforms/InstCombine/vec_phi_extract.ll
index ea610b0b0ad..15eb94aad69 100644
--- a/test/Transforms/InstCombine/vec_phi_extract.ll
+++ b/test/Transforms/InstCombine/vec_phi_extract.ll
@@ -91,7 +91,7 @@ for.cond:
   %input_1.addr.1 = phi <3 x i32> [ undef, %entry ], [ %dec43, %for.body ]
   br i1 undef, label %for.end, label %for.body
 
-; CHECK: extractelement <3 x i32> %{{.*}}, i32 0
+; CHECK-NOT: extractelement <3 x i32> %{{.*}}, i32 0
 for.body:
   %dec43 = add <3 x i32> %input_1.addr.1, <i32 -1, i32 -1, i32 -1>
   %sub44 = sub <3 x i32> <i32 -1, i32 -1, i32 -1>, %dec43
diff --git a/test/Transforms/InstCombine/xor.ll b/test/Transforms/InstCombine/xor.ll
index 5d4bd43512b..16757711427 100644
--- a/test/Transforms/InstCombine/xor.ll
+++ b/test/Transforms/InstCombine/xor.ll
@@ -188,6 +188,16 @@ define i32 @test15(i32 %A) {
   ret i32 %C
 }
 
+define <2 x i32> @test15vec(<2 x i32> %A) {
+; CHECK-LABEL: @test15vec(
+; CHECK-NEXT:    [[C:%.*]] = sub <2 x i32> zeroinitializer, [[A:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[C]]
+;
+  %B = add <2 x i32> %A, <i32 -1, i32 -1>
+  %C = xor <2 x i32> %B, <i32 -1, i32 -1>
+  ret <2 x i32> %C
+}
+
 define i32 @test16(i32 %A) {
 ; CHECK-LABEL: @test16(
 ; CHECK-NEXT:    [[C:%.*]] = sub i32 -124, %A
@@ -198,6 +208,16 @@ define i32 @test16(i32 %A) {
   ret i32 %C
 }
 
+define <2 x i32> @test16vec(<2 x i32> %A) {
+; CHECK-LABEL: @test16vec(
+; CHECK-NEXT:    [[C:%.*]] = sub <2 x i32> <i32 -124, i32 -124>, [[A:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[C]]
+;
+  %B = add <2 x i32> %A, <i32 123, i32 123>
+  %C = xor <2 x i32> %B, <i32 -1, i32 -1>
+  ret <2 x i32> %C
+}
+
 define i32 @test17(i32 %A) {
 ; CHECK-LABEL: @test17(
 ; CHECK-NEXT:    [[C:%.*]] = add i32 %A, -124
@@ -208,6 +228,16 @@ define i32 @test17(i32 %A) {
   ret i32 %C
 }
 
+define <2 x i32> @test17vec(<2 x i32> %A) {
+; CHECK-LABEL: @test17vec(
+; CHECK-NEXT:    [[C:%.*]] = add <2 x i32> [[A:%.*]], <i32 -124, i32 -124>
+; CHECK-NEXT:    ret <2 x i32> [[C]]
+;
+  %B = sub <2 x i32> <i32 123, i32 123>, %A
+  %C = xor <2 x i32> %B, <i32 -1, i32 -1>
+  ret <2 x i32> %C
+}
+
 define i32 @test18(i32 %A) {
 ; CHECK-LABEL: @test18(
 ; CHECK-NEXT:    [[C:%.*]] = add i32 %A, 124
-- 
2.40.0