[llvm] r299366 - Revert r299337 "[InstCombine] Remove redundant combine from visitAnd"
Craig Topper via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 3 10:22:24 PDT 2017
Author: ctopper
Date: Mon Apr 3 12:22:23 2017
New Revision: 299366
URL: http://llvm.org/viewvc/llvm-project?rev=299366&view=rev
Log:
Revert r299337 "[InstCombine] Remove redundant combine from visitAnd"
One of the tsan bots started failing at this commit. I don't see anything obviously wrong with the commit so trying this to see if it recovers.
Failing log: http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux-autoconf/builds/6792
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=299366&r1=299365&r2=299366&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Mon Apr 3 12:22:23 2017
@@ -295,6 +295,77 @@ Value *InstCombiner::insertRangeTest(Val
return Builder->CreateICmp(Pred, VMinusLo, HiMinusLo);
}
+/// Returns true iff Val consists of one contiguous run of 1s with any number
+/// of 0s on either side. The 1s are allowed to wrap from LSB to MSB,
+/// so 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs. 0x0F0F0000 is
+/// not, since all 1s are not contiguous.
+static bool isRunOfOnes(ConstantInt *Val, uint32_t &MB, uint32_t &ME) {
+ const APInt& V = Val->getValue();
+ uint32_t BitWidth = Val->getType()->getBitWidth();
+ if (!V.isShiftedMask()) return false;
+
+ // look for the first zero bit after the run of ones
+ MB = BitWidth - ((V - 1) ^ V).countLeadingZeros();
+ // look for the first non-zero bit
+ ME = V.getActiveBits();
+ return true;
+}
+
+/// This is part of an expression (LHS +/- RHS) & Mask, where isSub determines
+/// whether the operator is a sub. If we can fold one of the following xforms:
+///
+/// ((A & N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == Mask
+/// ((A | N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+/// ((A ^ N) +/- B) & Mask -> (A +/- B) & Mask iff N&Mask == 0
+///
+/// return (A +/- B).
+///
+Value *InstCombiner::FoldLogicalPlusAnd(Value *LHS, Value *RHS,
+ ConstantInt *Mask, bool isSub,
+ Instruction &I) {
+ Instruction *LHSI = dyn_cast<Instruction>(LHS);
+ if (!LHSI || LHSI->getNumOperands() != 2 ||
+ !isa<ConstantInt>(LHSI->getOperand(1))) return nullptr;
+
+ ConstantInt *N = cast<ConstantInt>(LHSI->getOperand(1));
+
+ switch (LHSI->getOpcode()) {
+ default: return nullptr;
+ case Instruction::And:
+ if (ConstantExpr::getAnd(N, Mask) == Mask) {
+ // If the AndRHS is a power of two minus one (0+1+), this is simple.
+ if ((Mask->getValue().countLeadingZeros() +
+ Mask->getValue().countPopulation()) ==
+ Mask->getValue().getBitWidth())
+ break;
+
+ // Otherwise, if Mask is 0+1+0+, and if B is known to have the low 0+
+ // part, we don't need any explicit masks to take them out of A. If that
+ // is all N is, ignore it.
+ uint32_t MB = 0, ME = 0;
+ if (isRunOfOnes(Mask, MB, ME)) { // begin/end bit of run, inclusive
+ uint32_t BitWidth = cast<IntegerType>(RHS->getType())->getBitWidth();
+ APInt Mask(APInt::getLowBitsSet(BitWidth, MB-1));
+ if (MaskedValueIsZero(RHS, Mask, 0, &I))
+ break;
+ }
+ }
+ return nullptr;
+ case Instruction::Or:
+ case Instruction::Xor:
+ // If the AndRHS is a power of two minus one (0+1+), and N&Mask == 0
+ if ((Mask->getValue().countLeadingZeros() +
+ Mask->getValue().countPopulation()) == Mask->getValue().getBitWidth()
+ && ConstantExpr::getAnd(N, Mask)->isNullValue())
+ break;
+ return nullptr;
+ }
+
+ if (isSub)
+ return Builder->CreateSub(LHSI->getOperand(0), RHS, "fold");
+ return Builder->CreateAdd(LHSI->getOperand(0), RHS, "fold");
+}
+
/// Classify (icmp eq (A & B), C) and (icmp ne (A & B), C) as matching patterns
/// that can be simplified.
/// One of A and B is considered the mask. The other is the value. This is
@@ -1249,7 +1320,23 @@ Instruction *InstCombiner::visitAnd(Bina
break;
}
+ case Instruction::Add:
+ // ((A & N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == AndRHS.
+ // ((A | N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+ // ((A ^ N) + B) & AndRHS -> (A + B) & AndRHS iff N&AndRHS == 0
+ if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, false, I))
+ return BinaryOperator::CreateAnd(V, AndRHS);
+ if (Value *V = FoldLogicalPlusAnd(Op0RHS, Op0LHS, AndRHS, false, I))
+ return BinaryOperator::CreateAnd(V, AndRHS); // Add commutes
+ break;
+
case Instruction::Sub:
+ // ((A & N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == AndRHS.
+ // ((A | N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+ // ((A ^ N) - B) & AndRHS -> (A - B) & AndRHS iff N&AndRHS == 0
+ if (Value *V = FoldLogicalPlusAnd(Op0LHS, Op0RHS, AndRHS, true, I))
+ return BinaryOperator::CreateAnd(V, AndRHS);
+
// -x & 1 -> x & 1
if (AndRHSMask == 1 && match(Op0LHS, m_Zero()))
return BinaryOperator::CreateAnd(Op0RHS, AndRHS);
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h?rev=299366&r1=299365&r2=299366&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h Mon Apr 3 12:22:23 2017
@@ -653,6 +653,8 @@ private:
Instruction *OptAndOp(BinaryOperator *Op, ConstantInt *OpRHS,
ConstantInt *AndRHS, BinaryOperator &TheAnd);
+ Value *FoldLogicalPlusAnd(Value *LHS, Value *RHS, ConstantInt *Mask,
+ bool isSub, Instruction &I);
Value *insertRangeTest(Value *V, const APInt &Lo, const APInt &Hi,
bool isSigned, bool Inside);
Instruction *PromoteCastOfAllocation(BitCastInst &CI, AllocaInst &AI);
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