[llvm-commits] [llvm] r86443 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/phi.ll test/Transforms/InstCombine/sext-misc.ll
Chris Lattner
sabre at nondot.org
Sun Nov 8 00:21:14 PST 2009
Author: lattner
Date: Sun Nov 8 02:21:13 2009
New Revision: 86443
URL: http://llvm.org/viewvc/llvm-project?rev=86443&view=rev
Log:
teach a couple of instcombine transformations involving PHIs to
not turn a PHI in a legal type into a PHI of an illegal type, and
add a new optimization that breaks up insane integer PHI nodes into
small pieces (PR3451).
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/phi.ll
llvm/trunk/test/Transforms/InstCombine/sext-misc.ll
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=86443&r1=86442&r2=86443&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Sun Nov 8 02:21:13 2009
@@ -283,6 +283,8 @@
Instruction *visitSelectInstWithICmp(SelectInst &SI, ICmpInst *ICI);
Instruction *visitCallInst(CallInst &CI);
Instruction *visitInvokeInst(InvokeInst &II);
+
+ Instruction *SliceUpIllegalIntegerPHI(PHINode &PN);
Instruction *visitPHINode(PHINode &PN);
Instruction *visitGetElementPtrInst(GetElementPtrInst &GEP);
Instruction *visitAllocaInst(AllocaInst &AI);
@@ -8083,8 +8085,7 @@
Value *InstCombiner::EvaluateInDifferentType(Value *V, const Type *Ty,
bool isSigned) {
if (Constant *C = dyn_cast<Constant>(V))
- return ConstantExpr::getIntegerCast(C, Ty,
- isSigned /*Sext or ZExt*/);
+ return ConstantExpr::getIntegerCast(C, Ty, isSigned /*Sext or ZExt*/);
// Otherwise, it must be an instruction.
Instruction *I = cast<Instruction>(V);
@@ -8117,8 +8118,7 @@
return I->getOperand(0);
// Otherwise, must be the same type of cast, so just reinsert a new one.
- Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),
- Ty);
+ Res = CastInst::Create(cast<CastInst>(I)->getOpcode(), I->getOperand(0),Ty);
break;
case Instruction::Select: {
Value *True = EvaluateInDifferentType(I->getOperand(1), Ty, isSigned);
@@ -8167,9 +8167,17 @@
return NV;
// If we are casting a PHI then fold the cast into the PHI
- if (isa<PHINode>(Src))
- if (Instruction *NV = FoldOpIntoPhi(CI))
- return NV;
+ if (isa<PHINode>(Src)) {
+ // We don't do this if this would create a PHI node with an illegal type if
+ // it is currently legal.
+ if (!isa<IntegerType>(Src->getType()) ||
+ !isa<IntegerType>(CI.getType()) ||
+ (TD && TD->isLegalInteger(CI.getType()->getPrimitiveSizeInBits())) ||
+ (TD && !TD->isLegalInteger(Src->getType()->getPrimitiveSizeInBits())))
+ if (Instruction *NV = FoldOpIntoPhi(CI))
+ return NV;
+
+ }
return 0;
}
@@ -8508,7 +8516,7 @@
return BinaryOperator::CreateLShr(V1, V2);
}
}
-
+
return 0;
}
@@ -10886,6 +10894,15 @@
if (isa<CastInst>(FirstInst)) {
CastSrcTy = FirstInst->getOperand(0)->getType();
+
+ // If this is a legal integer PHI node, and pulling the operation through
+ // would cause it to be an illegal integer PHI, don't do the transformation.
+ if (!TD ||
+ (isa<IntegerType>(PN.getType()) &&
+ isa<IntegerType>(CastSrcTy) &&
+ TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()) &&
+ !TD->isLegalInteger(CastSrcTy->getPrimitiveSizeInBits())))
+ return 0;
} else if (isa<BinaryOperator>(FirstInst) || isa<CmpInst>(FirstInst)) {
// Can fold binop, compare or shift here if the RHS is a constant,
// otherwise call FoldPHIArgBinOpIntoPHI.
@@ -10998,6 +11015,123 @@
}
+namespace {
+struct PHIUsageRecord {
+ unsigned Shift; // The amount shifted.
+ Instruction *Inst; // The trunc instruction.
+
+ PHIUsageRecord(unsigned Sh, Instruction *User) : Shift(Sh), Inst(User) {}
+
+ bool operator<(const PHIUsageRecord &RHS) const {
+ if (Shift < RHS.Shift) return true;
+ return Shift == RHS.Shift &&
+ Inst->getType()->getPrimitiveSizeInBits() <
+ RHS.Inst->getType()->getPrimitiveSizeInBits();
+ }
+};
+}
+
+
+/// SliceUpIllegalIntegerPHI - This is an integer PHI and we know that it has an
+/// illegal type: see if it is only used by trunc or trunc(lshr) operations. If
+/// so, we split the PHI into the various pieces being extracted. This sort of
+/// thing is introduced when SROA promotes an aggregate to large integer values.
+///
+/// TODO: The user of the trunc may be an bitcast to float/double/vector or an
+/// inttoptr. We should produce new PHIs in the right type.
+///
+Instruction *InstCombiner::SliceUpIllegalIntegerPHI(PHINode &PN) {
+ SmallVector<PHIUsageRecord, 16> PHIUsers;
+
+ for (Value::use_iterator UI = PN.use_begin(), E = PN.use_end();
+ UI != E; ++UI) {
+ Instruction *User = cast<Instruction>(*UI);
+
+ // The PHI can use itself.
+ if (User == &PN)
+ continue;
+
+ // Truncates are always ok.
+ if (isa<TruncInst>(User)) {
+ PHIUsers.push_back(PHIUsageRecord(0, User));
+ continue;
+ }
+
+ // Otherwise it must be a lshr which can only be used by one trunc.
+ if (User->getOpcode() != Instruction::LShr ||
+ !User->hasOneUse() || !isa<TruncInst>(User->use_back()) ||
+ !isa<ConstantInt>(User->getOperand(1)))
+ return 0;
+
+ unsigned Shift = cast<ConstantInt>(User->getOperand(1))->getZExtValue();
+ PHIUsers.push_back(PHIUsageRecord(Shift, User->use_back()));
+ }
+
+ // If we have no users, they must be all self uses, just nuke the PHI.
+ if (PHIUsers.empty())
+ return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+
+ // If this phi node is transformable, create new PHIs for all the pieces
+ // extracted out of it. First, sort the users by their offset and size.
+ array_pod_sort(PHIUsers.begin(), PHIUsers.end());
+
+
+ DenseMap<BasicBlock*, Value*> PredValues;
+
+ unsigned UserI = 0, UserE = PHIUsers.size();
+ while (1) {
+ assert(UserI != UserE && "Iteration fail, loop below should catch this");
+
+ unsigned Offset = PHIUsers[UserI].Shift;
+ const Type *Ty = PHIUsers[UserI].Inst->getType();
+
+ // Create the new PHI node for this user.
+ PHINode *EltPHI =
+ PHINode::Create(Ty, PN.getName()+".off"+Twine(Offset), &PN);
+
+ for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i) {
+ BasicBlock *Pred = PN.getIncomingBlock(i);
+ Value *&PredVal = PredValues[Pred];
+
+ // If we already have a value for this predecessor, reuse it.
+ if (PredVal) {
+ EltPHI->addIncoming(PredVal, Pred);
+ continue;
+ }
+
+ // Handle the PHI self-reuse case.
+ Value *InVal = PN.getIncomingValue(i);
+ if (InVal == &PN) {
+ PredVal = EltPHI;
+ EltPHI->addIncoming(PredVal, Pred);
+ continue;
+ }
+
+ // Otherwise, do an extract in the predecessor.
+ Builder->SetInsertPoint(Pred, Pred->getTerminator());
+ if (Offset)
+ InVal = Builder->CreateLShr(InVal, ConstantInt::get(InVal->getType(),
+ Offset), "extract");
+ InVal = Builder->CreateTrunc(InVal, Ty, "extract.t");
+ PredVal = InVal;
+ EltPHI->addIncoming(PredVal, Pred);
+ }
+ PredValues.clear();
+
+ // Now that we have a new PHI node, replace all uses of this piece of the
+ // PHI with the one new PHI.
+ while (PHIUsers[UserI].Shift == Offset &&
+ PHIUsers[UserI].Inst->getType() == Ty) {
+ ReplaceInstUsesWith(*PHIUsers[UserI].Inst, EltPHI);
+
+ // If we replaced the last PHI user, we're done. Just replace all the
+ // remaining uses of the PHI (self uses and the lshrs with undefs.
+ if (++UserI == UserE)
+ return ReplaceInstUsesWith(PN, UndefValue::get(PN.getType()));
+ }
+ }
+}
+
// PHINode simplification
//
Instruction *InstCombiner::visitPHINode(PHINode &PN) {
@@ -11103,6 +11237,15 @@
}
}
+ // If this is an integer PHI and we know that it has an illegal type, see if
+ // it is only used by trunc or trunc(lshr) operations. If so, we split the
+ // PHI into the various pieces being extracted. This sort of thing is
+ // introduced when SROA promotes an aggregate to a single large integer type.
+ if (isa<IntegerType>(PN.getType()) && TD &&
+ !TD->isLegalInteger(PN.getType()->getPrimitiveSizeInBits()))
+ if (Instruction *Res = SliceUpIllegalIntegerPHI(PN))
+ return Res;
+
return 0;
}
Modified: llvm/trunk/test/Transforms/InstCombine/phi.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/phi.ll?rev=86443&r1=86442&r2=86443&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/phi.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/phi.ll Sun Nov 8 02:21:13 2009
@@ -2,6 +2,8 @@
;
; RUN: opt < %s -instcombine -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+
define i32 @test1(i32 %A, i1 %b) {
BB0:
br i1 %b, label %BB1, label %BB2
Modified: llvm/trunk/test/Transforms/InstCombine/sext-misc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/sext-misc.ll?rev=86443&r1=86442&r2=86443&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/sext-misc.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/sext-misc.ll Sun Nov 8 02:21:13 2009
@@ -1,5 +1,7 @@
; RUN: opt < %s -instcombine -S | not grep sext
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
+
declare i32 @llvm.ctpop.i32(i32)
declare i32 @llvm.ctlz.i32(i32)
declare i32 @llvm.cttz.i32(i32)
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