[llvm] r310232 - [InstCombine] Support '(C - X) ^ signmask -> (C + signmask - X)' and '(X + C) ^ signmask -> (X + C + signmask)' for vector splats.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Sun Aug  6 15:17:21 2017
New Revision: 310232

URL: http://llvm.org/viewvc/llvm-project?rev=310232&view=rev
Log:
[InstCombine] Support '(C - X) ^ signmask -> (C + signmask - X)' and '(X + C) ^ signmask -> (X + C + signmask)' for vector splats.

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
    llvm/trunk/test/Transforms/InstCombine/xor.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=310232&r1=310231&r2=310232&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Sun Aug  6 15:17:21 2017
@@ -2430,35 +2430,30 @@ Instruction *InstCombiner::visitXor(Bina
           Constant *NewC = ConstantInt::get(I.getType(), -(*C) - 1);
           return BinaryOperator::CreateAdd(V, NewC);
         }
+        if (RHSC->isSignMask()) {
+          // (C - X) ^ signmask -> (C + signmask - X)
+          Constant *NewC = ConstantInt::get(I.getType(), *C + *RHSC);
+          return BinaryOperator::CreateSub(NewC, V);
+        }
       } 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 (RHSC->isSignMask()) {
+          // (X + C) ^ signmask -> (X + C + signmask)
+          Constant *NewC = ConstantInt::get(I.getType(), *C + *RHSC);
+          return BinaryOperator::CreateAdd(V, NewC);
+        }
       }
     }
   }
 
   if (ConstantInt *RHSC = dyn_cast<ConstantInt>(Op1)) {
     if (BinaryOperator *Op0I = dyn_cast<BinaryOperator>(Op0)) {
-      if (Op0I->getOpcode() == Instruction::Sub)
-        if (ConstantInt *Op0I0C = dyn_cast<ConstantInt>(Op0I->getOperand(0))) {
-          // (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));
-          }
-        }
-
       if (ConstantInt *Op0CI = dyn_cast<ConstantInt>(Op0I->getOperand(1))) {
-        if (Op0I->getOpcode() == Instruction::Add) {
-          // (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);
-          }
-        } else if (Op0I->getOpcode() == Instruction::Or) {
+        if (Op0I->getOpcode() == Instruction::Or) {
           // (X|C1)^C2 -> X^(C1|C2) iff X&~C1 == 0
           if (MaskedValueIsZero(Op0I->getOperand(0), Op0CI->getValue(),
                                 0, &I)) {

Modified: llvm/trunk/test/Transforms/InstCombine/xor.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/xor.ll?rev=310232&r1=310231&r2=310232&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/xor.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/xor.ll Sun Aug  6 15:17:21 2017
@@ -383,6 +383,16 @@ define i32 @test28(i32 %indvar) {
   ret i32 %t214
 }
 
+define <2 x i32> @test28vec(<2 x i32> %indvar) {
+; CHECK-LABEL: @test28vec(
+; CHECK-NEXT:    [[T214:%.*]] = add <2 x i32> [[INDVAR:%.*]], <i32 1, i32 1>
+; CHECK-NEXT:    ret <2 x i32> [[T214]]
+;
+  %t7 = add <2 x i32> %indvar, <i32 -2147483647, i32 -2147483647>
+  %t214 = xor <2 x i32> %t7, <i32 -2147483648, i32 -2147483648>
+  ret <2 x i32> %t214
+}
+
 define i32 @test28_sub(i32 %indvar) {
 ; CHECK-LABEL: @test28_sub(
 ; CHECK-NEXT:    [[T214:%.*]] = sub i32 1, [[INDVAR:%.*]]
@@ -393,6 +403,16 @@ define i32 @test28_sub(i32 %indvar) {
   ret i32 %t214
 }
 
+define <2 x i32> @test28_subvec(<2 x i32> %indvar) {
+; CHECK-LABEL: @test28_subvec(
+; CHECK-NEXT:    [[T214:%.*]] = sub <2 x i32> <i32 1, i32 1>, [[INDVAR:%.*]]
+; CHECK-NEXT:    ret <2 x i32> [[T214]]
+;
+  %t7 = sub <2 x i32> <i32 -2147483647, i32 -2147483647>, %indvar
+  %t214 = xor <2 x i32> %t7, <i32 -2147483648, i32 -2147483648>
+  ret <2 x i32> %t214
+}
+
 define i32 @test29(i1 %C) {
 ; CHECK-LABEL: @test29(
 ; CHECK-NEXT:    [[V:%.*]] = select i1 [[C:%.*]], i32 915, i32 113