[llvm] r211765 - Added instruction combine to transform few more negative values addition to subtraction (Part 2)
Dinesh Dwivedi
dinesh.d at samsung.com
Wed Jun 25 22:40:23 PDT 2014
Author: dinesh
Date: Thu Jun 26 00:40:22 2014
New Revision: 211765
URL: http://llvm.org/viewvc/llvm-project?rev=211765&view=rev
Log:
Added instruction combine to transform few more negative values addition to subtraction (Part 2)
This patch enables transforms for
(x + (~(y | c) + 1) --> x - (y | c) if c is even
Differential Revision: http://reviews.llvm.org/D4209
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
llvm/trunk/test/Transforms/InstCombine/add2.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=211765&r1=211764&r2=211765&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Thu Jun 26 00:40:22 2014
@@ -957,59 +957,64 @@ bool InstCombiner::WillNotOverflowUnsign
}
// Checks if any operand is negative and we can convert add to sub.
-// This function checks for following negative patterns
-// ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C))
-// TODO: ADD(XOR(AND(Z, ~C), ~C), 1) == NEG(OR(Z, C)) if C is even
-// TODO: XOR(AND(Z, ~C), (~C + 1)) == NEG(OR(Z, C)) if C is odd
-Value *checkForNegativeOperand(BinaryOperator &I,
- InstCombiner::BuilderTy *Builder) {
- Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
-
- // This function creates 2 instructions to replace ADD, we need at least one
- // of LHS or RHS to have one use to ensure benefit in transform.
- if (!LHS->hasOneUse() && !RHS->hasOneUse())
- return nullptr;
-
- bool IHasNSW = I.hasNoSignedWrap();
- bool IHasNUW = I.hasNoUnsignedWrap();
-
- Value *X = nullptr, *Y = nullptr, *Z = nullptr;
- const APInt *C1 = nullptr, *C2 = nullptr;
-
- // if ONE is on other side, swap
- if (match(RHS, m_Add(m_Value(X), m_One())))
- std::swap(LHS, RHS);
-
- if (match(LHS, m_Add(m_Value(X), m_One()))) {
- // if XOR on other side, swap
- if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1))))
- std::swap(X, RHS);
-
- // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1))
- // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1))
- if (match(X, m_Xor(m_Value(Y), m_APInt(C1)))) {
- if (match(Y, m_Or(m_Value(Z), m_APInt(C2))) && (*C2 == ~(*C1))) {
- Value *NewAnd = Builder->CreateAnd(Z, *C1);
- return Builder->CreateSub(RHS, NewAnd, "", IHasNUW, IHasNSW);
- }
- }
- }
-
- return nullptr;
-}
-
-Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
- bool Changed = SimplifyAssociativeOrCommutative(I);
- Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+ // This function checks for following negative patterns
+ // ADD(XOR(OR(Z, NOT(C)), C)), 1) == NEG(AND(Z, C))
+ // ADD(XOR(AND(Z, C), C), 1) == NEG(OR(Z, ~C)) if C is odd
+ // TODO: XOR(AND(Z, C), (C + 1)) == NEG(OR(Z, ~C)) if C is even
+ Value *checkForNegativeOperand(BinaryOperator &I,
+ InstCombiner::BuilderTy *Builder) {
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+ // This function creates 2 instructions to replace ADD, we need at least one
+ // of LHS or RHS to have one use to ensure benefit in transform.
+ if (!LHS->hasOneUse() && !RHS->hasOneUse())
+ return nullptr;
+
+ Value *X = nullptr, *Y = nullptr, *Z = nullptr;
+ const APInt *C1 = nullptr, *C2 = nullptr;
+
+ // if ONE is on other side, swap
+ if (match(RHS, m_Add(m_Value(X), m_One())))
+ std::swap(LHS, RHS);
+
+ if (match(LHS, m_Add(m_Value(X), m_One()))) {
+ // if XOR on other side, swap
+ if (match(RHS, m_Xor(m_Value(Y), m_APInt(C1))))
+ std::swap(X, RHS);
+
+ if (match(X, m_Xor(m_Value(Y), m_APInt(C1)))) {
+ // X = XOR(Y, C1), Y = OR(Z, C2), C2 = NOT(C1) ==> X == NOT(AND(Z, C1))
+ // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, AND(Z, C1))
+ if (match(Y, m_Or(m_Value(Z), m_APInt(C2))) && (*C2 == ~(*C1))) {
+ Value *NewAnd = Builder->CreateAnd(Z, *C1);
+ return Builder->CreateSub(RHS, NewAnd, "sub");
+ } else if (C1->countTrailingZeros() == 0) {
+ // if C1 is ODD and
+ // X = XOR(Y, C1), Y = AND(Z, C2), C2 == C1 ==> X == NOT(OR(Z, ~C1))
+ // ADD(ADD(X, 1), RHS) == ADD(X, ADD(RHS, 1)) == SUB(RHS, OR(Z, ~C1))
+ if (match(Y, m_And(m_Value(Z), m_APInt(C2))) && (*C1 == *C2)) {
+ Value *NewOr = Builder->CreateOr(Z, ~(*C1));
+ return Builder->CreateSub(RHS, NewOr, "sub");
+ }
+ }
+ }
+ }
- if (Value *V = SimplifyVectorOp(I))
- return ReplaceInstUsesWith(I, V);
+ return nullptr;
+ }
- if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
- I.hasNoUnsignedWrap(), DL))
- return ReplaceInstUsesWith(I, V);
+ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
+ bool Changed = SimplifyAssociativeOrCommutative(I);
+ Value *LHS = I.getOperand(0), *RHS = I.getOperand(1);
+
+ if (Value *V = SimplifyVectorOp(I))
+ return ReplaceInstUsesWith(I, V);
+
+ if (Value *V = SimplifyAddInst(LHS, RHS, I.hasNoSignedWrap(),
+ I.hasNoUnsignedWrap(), DL))
+ return ReplaceInstUsesWith(I, V);
- // (A*B)+(A*C) -> A*(B+C) etc
+ // (A*B)+(A*C) -> A*(B+C) etc
if (Value *V = SimplifyUsingDistributiveLaws(I))
return ReplaceInstUsesWith(I, V);
Modified: llvm/trunk/test/Transforms/InstCombine/add2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/add2.ll?rev=211765&r1=211764&r2=211765&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/add2.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/add2.ll Thu Jun 26 00:40:22 2014
@@ -150,6 +150,32 @@ define i32 @test14(i32 %x, i32 %y) {
; CHECK-NEXT: ret i32 [[SUB]]
}
+define i32 @test15(i32 %x, i32 %y) {
+ %x.not = and i32 %x, -1431655767
+ %neg = xor i32 %x.not, -1431655767
+ %add = add i32 %y, 1
+ %add1 = add i32 %add, %neg
+ ret i32 %add1
+; CHECK-LABEL: @test15(
+; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 %x, 1431655766
+; CHECK-NEXT: [[SUB:%[a-z0-9]+]] = sub i32 %y, [[OR]]
+; CHECK-NEXT: ret i32 [[SUB]]
+}
+
+define i32 @test16(i32 %x, i32 %y) {
+ %shr = ashr i32 %x, 3
+ %shr.not = and i32 %shr, -1431655767
+ %neg = xor i32 %shr.not, -1431655767
+ %add = add i32 %y, 1
+ %add1 = add i32 %add, %neg
+ ret i32 %add1
+; CHECK-LABEL: @test16(
+; CHECK-NEXT: [[SHR:%[a-z0-9]+]] = ashr i32 %x, 3
+; CHECK-NEXT: [[OR:%[a-z0-9]+]] = or i32 [[SHR]], 1431655766
+; CHECK-NEXT: [[SUB:%[a-z0-9]+]] = sub i32 %y, [[OR]]
+; CHECK-NEXT: ret i32 [[SUB]]
+}
+
define i16 @add_nsw_mul_nsw(i16 %x) {
%add1 = add nsw i16 %x, %x
%add2 = add nsw i16 %add1, %x
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