[llvm] r221129 - InstCombine: Combine (X | Y) - X to (~X & Y)
David Majnemer
david.majnemer at gmail.com
Sun Nov 2 21:53:56 PST 2014
Author: majnemer
Date: Sun Nov 2 23:53:55 2014
New Revision: 221129
URL: http://llvm.org/viewvc/llvm-project?rev=221129&view=rev
Log:
InstCombine: Combine (X | Y) - X to (~X & Y)
This implements the transformation from (X | Y) - X to (~X & Y).
Differential Revision: http://reviews.llvm.org/D5791
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
llvm/trunk/test/Transforms/InstCombine/sub.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp?rev=221129&r1=221128&r2=221129&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAddSub.cpp Sun Nov 2 23:53:55 2014
@@ -1431,11 +1431,11 @@ Instruction *InstCombiner::visitFAdd(Bin
Z2 = dyn_cast<Constant>(B2); B = B1;
} else if (match(B1, m_AnyZero()) && match(A2, m_AnyZero())) {
Z1 = dyn_cast<Constant>(B1); B = B2;
- Z2 = dyn_cast<Constant>(A2); A = A1;
+ Z2 = dyn_cast<Constant>(A2); A = A1;
}
-
- if (Z1 && Z2 &&
- (I.hasNoSignedZeros() ||
+
+ if (Z1 && Z2 &&
+ (I.hasNoSignedZeros() ||
(Z1->isNegativeZeroValue() && Z2->isNegativeZeroValue()))) {
return SelectInst::Create(C, A, B);
}
@@ -1594,7 +1594,7 @@ Instruction *InstCombiner::visitSub(Bina
// -(X >>u 31) -> (X >>s 31)
// -(X >>s 31) -> (X >>u 31)
if (C->isZero()) {
- Value *X;
+ Value *X;
ConstantInt *CI;
if (match(Op1, m_LShr(m_Value(X), m_ConstantInt(CI))) &&
// Verify we are shifting out everything but the sign bit.
@@ -1609,7 +1609,7 @@ Instruction *InstCombiner::visitSub(Bina
}
- {
+ {
Value *Y;
// X-(X+Y) == -Y X-(Y+X) == -Y
if (match(Op1, m_Add(m_Specific(Op0), m_Value(Y))) ||
@@ -1630,6 +1630,15 @@ Instruction *InstCombiner::visitSub(Bina
return BinaryOperator::CreateAnd(A, B);
}
+ if (Op0->hasOneUse()) {
+ Value *Y = nullptr;
+ // ((X | Y) - X) --> (~X & Y)
+ if (match(Op0, m_Or(m_Value(Y), m_Specific(Op1))) ||
+ match(Op0, m_Or(m_Specific(Op1), m_Value(Y))))
+ return BinaryOperator::CreateAnd(
+ Y, Builder->CreateNot(Op1, Op1->getName() + ".not"));
+ }
+
if (Op1->hasOneUse()) {
Value *X = nullptr, *Y = nullptr, *Z = nullptr;
Constant *C = nullptr;
Modified: llvm/trunk/test/Transforms/InstCombine/sub.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/sub.ll?rev=221129&r1=221128&r2=221129&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/sub.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/sub.ll Sun Nov 2 23:53:55 2014
@@ -540,3 +540,13 @@ define i32 @test45(i32 %x, i32 %y) {
; CHECK-NEXT: %sub = and i32 %x, %y
; CHECK: ret i32 %sub
}
+
+define i32 @test46(i32 %x, i32 %y) {
+ %or = or i32 %x, %y
+ %sub = sub i32 %or, %x
+ ret i32 %sub
+; CHECK-LABEL: @test46(
+; CHECK-NEXT: %x.not = xor i32 %x, -1
+; CHECK-NEXT: %sub = and i32 %y, %x.not
+; CHECK: ret i32 %sub
+}
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