[PATCH] D32703: [InstCombine] check one-use before applying DeMorgan nor/nand folds
Sanjay Patel via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Mon May 1 15:38:56 PDT 2017
This revision was automatically updated to reflect the committed changes.
Closed by commit rL301848: [InstCombine] check one-use before applying DeMorgan nor/nand folds (authored by spatel).
Changed prior to commit:
https://reviews.llvm.org/D32703?vs=97304&id=97350#toc
Repository:
rL LLVM
https://reviews.llvm.org/D32703
Files:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
llvm/trunk/test/Transforms/InstCombine/demorgan.ll
Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -2438,16 +2438,20 @@
if (match(&I, m_Not(m_BinOp(NotOp)))) {
if (NotOp->getOpcode() == Instruction::And ||
NotOp->getOpcode() == Instruction::Or) {
- // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
- // ~(~X | Y) === (X & ~Y) - De Morgan's Law
- if (dyn_castNotVal(NotOp->getOperand(1)))
- NotOp->swapOperands();
- if (Value *Op0NotVal = dyn_castNotVal(NotOp->getOperand(0))) {
- Value *NotY = Builder->CreateNot(
- NotOp->getOperand(1), NotOp->getOperand(1)->getName() + ".not");
- if (NotOp->getOpcode() == Instruction::And)
- return BinaryOperator::CreateOr(Op0NotVal, NotY);
- return BinaryOperator::CreateAnd(Op0NotVal, NotY);
+ // We must eliminate the and/or for this transform to not increase the
+ // instruction count.
+ if (NotOp->hasOneUse()) {
+ // ~(~X & Y) --> (X | ~Y) - De Morgan's Law
+ // ~(~X | Y) === (X & ~Y) - De Morgan's Law
+ if (dyn_castNotVal(NotOp->getOperand(1)))
+ NotOp->swapOperands();
+ if (Value *Op0NotVal = dyn_castNotVal(NotOp->getOperand(0))) {
+ Value *NotY = Builder->CreateNot(
+ NotOp->getOperand(1), NotOp->getOperand(1)->getName() + ".not");
+ if (NotOp->getOpcode() == Instruction::And)
+ return BinaryOperator::CreateOr(Op0NotVal, NotY);
+ return BinaryOperator::CreateAnd(Op0NotVal, NotY);
+ }
}
// ~(X & Y) --> (~X | ~Y) - De Morgan's Law
Index: llvm/trunk/test/Transforms/InstCombine/demorgan.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/demorgan.ll
+++ llvm/trunk/test/Transforms/InstCombine/demorgan.ll
@@ -286,8 +286,7 @@
; CHECK-NEXT: [[NOTA:%.*]] = xor i8 %A, -1
; CHECK-NEXT: [[C:%.*]] = or i8 [[NOTA]], %B
; CHECK-NEXT: [[USE2C:%.*]] = mul i8 [[C]], 23
-; CHECK-NEXT: [[B_NOT:%.*]] = xor i8 %B, -1
-; CHECK-NEXT: [[NOTC:%.*]] = and i8 [[B_NOT]], %A
+; CHECK-NEXT: [[NOTC:%.*]] = xor i8 [[C]], -1
; CHECK-NEXT: [[R:%.*]] = sdiv i8 [[NOTC]], [[USE2C]]
; CHECK-NEXT: ret i8 [[R]]
;
@@ -330,8 +329,7 @@
; CHECK-NEXT: [[USE2A:%.*]] = mul i8 [[NOTA]], 17
; CHECK-NEXT: [[C:%.*]] = or i8 [[NOTA]], %B
; CHECK-NEXT: [[USE2C:%.*]] = mul i8 [[C]], 23
-; CHECK-NEXT: [[B_NOT:%.*]] = xor i8 %B, -1
-; CHECK-NEXT: [[NOTC:%.*]] = and i8 [[B_NOT]], %A
+; CHECK-NEXT: [[NOTC:%.*]] = xor i8 [[C]], -1
; CHECK-NEXT: [[R1:%.*]] = sdiv i8 [[NOTC]], [[USE2C]]
; CHECK-NEXT: [[R2:%.*]] = sdiv i8 [[R1]], [[USE2A]]
; CHECK-NEXT: ret i8 [[R2]]
@@ -354,8 +352,7 @@
; CHECK-NEXT: [[NOTA:%.*]] = xor i8 %A, -1
; CHECK-NEXT: [[C:%.*]] = or i8 [[NOTA]], %B
; CHECK-NEXT: [[USE2C:%.*]] = mul i8 [[C]], 23
-; CHECK-NEXT: [[B_NOT:%.*]] = xor i8 %B, -1
-; CHECK-NEXT: [[NOTC:%.*]] = and i8 [[B_NOT]], %A
+; CHECK-NEXT: [[NOTC:%.*]] = xor i8 [[C]], -1
; CHECK-NEXT: [[R1:%.*]] = sdiv i8 [[NOTC]], [[USE2C]]
; CHECK-NEXT: [[R2:%.*]] = sdiv i8 [[R1]], [[USE2B]]
; CHECK-NEXT: ret i8 [[R2]]
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