[llvm-commits] [llvm] r141868 - /llvm/trunk/lib/Analysis/ScalarEvolutionNormalization.cpp
Andrew Trick
atrick at apple.com
Thu Oct 13 10:21:09 PDT 2011
Author: atrick
Date: Thu Oct 13 12:21:09 2011
New Revision: 141868
URL: http://llvm.org/viewvc/llvm-project?rev=141868&view=rev
Log:
SCEV: Rewrite TrandformForPostIncUse to handle expression DAGs, not
just expression trees.
Partially fixes PR11090. Test case will be with the full fix.
Modified:
llvm/trunk/lib/Analysis/ScalarEvolutionNormalization.cpp
Modified: llvm/trunk/lib/Analysis/ScalarEvolutionNormalization.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ScalarEvolutionNormalization.cpp?rev=141868&r1=141867&r2=141868&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ScalarEvolutionNormalization.cpp (original)
+++ llvm/trunk/lib/Analysis/ScalarEvolutionNormalization.cpp Thu Oct 13 12:21:09 2011
@@ -60,20 +60,40 @@
return true;
}
-const SCEV *llvm::TransformForPostIncUse(TransformKind Kind,
- const SCEV *S,
- Instruction *User,
- Value *OperandValToReplace,
- PostIncLoopSet &Loops,
- ScalarEvolution &SE,
- DominatorTree &DT) {
- if (isa<SCEVConstant>(S) || isa<SCEVUnknown>(S))
- return S;
+namespace {
+
+/// Hold the state used during post-inc expression transformation, including a
+/// map of transformed expressions.
+class PostIncTransform {
+ TransformKind Kind;
+ PostIncLoopSet &Loops;
+ ScalarEvolution &SE;
+ DominatorTree &DT;
+
+ DenseMap<const SCEV*, const SCEV*> Transformed;
+
+public:
+ PostIncTransform(TransformKind kind, PostIncLoopSet &loops,
+ ScalarEvolution &se, DominatorTree &dt):
+ Kind(kind), Loops(loops), SE(se), DT(dt) {}
+
+ const SCEV *TransformSubExpr(const SCEV *S, Instruction *User,
+ Value *OperandValToReplace);
+
+protected:
+ const SCEV *TransformImpl(const SCEV *S, Instruction *User,
+ Value *OperandValToReplace);
+};
+
+} // namespace
+
+/// Implement post-inc transformation for all valid expression types.
+const SCEV *PostIncTransform::
+TransformImpl(const SCEV *S, Instruction *User, Value *OperandValToReplace) {
if (const SCEVCastExpr *X = dyn_cast<SCEVCastExpr>(S)) {
const SCEV *O = X->getOperand();
- const SCEV *N = TransformForPostIncUse(Kind, O, User, OperandValToReplace,
- Loops, SE, DT);
+ const SCEV *N = TransformSubExpr(O, User, OperandValToReplace);
if (O != N)
switch (S->getSCEVType()) {
case scZeroExtend: return SE.getZeroExtendExpr(N, S->getType());
@@ -93,9 +113,7 @@
// Transform each operand.
for (SCEVNAryExpr::op_iterator I = AR->op_begin(), E = AR->op_end();
I != E; ++I) {
- const SCEV *O = *I;
- const SCEV *N = TransformForPostIncUse(Kind, O, LUser, 0, Loops, SE, DT);
- Operands.push_back(N);
+ Operands.push_back(TransformSubExpr(*I, LUser, 0));
}
// Conservatively use AnyWrap until/unless we need FlagNW.
const SCEV *Result = SE.getAddRecExpr(Operands, L, SCEV::FlagAnyWrap);
@@ -104,8 +122,8 @@
case NormalizeAutodetect:
if (IVUseShouldUsePostIncValue(User, OperandValToReplace, L, &DT)) {
const SCEV *TransformedStep =
- TransformForPostIncUse(Kind, AR->getStepRecurrence(SE),
- User, OperandValToReplace, Loops, SE, DT);
+ TransformSubExpr(AR->getStepRecurrence(SE),
+ User, OperandValToReplace);
Result = SE.getMinusSCEV(Result, TransformedStep);
Loops.insert(L);
}
@@ -114,24 +132,20 @@
// sometimes fails to canonicalize two equal SCEVs to exactly the same
// form. It's possibly a pessimization when this happens, but it isn't a
// correctness problem, so disable this assert for now.
- assert(S == TransformForPostIncUse(Denormalize, Result,
- User, OperandValToReplace,
- Loops, SE, DT) &&
+ assert(S == TransformSubExpr(Result, User, OperandValToReplace) &&
"SCEV normalization is not invertible!");
#endif
break;
case Normalize:
if (Loops.count(L)) {
const SCEV *TransformedStep =
- TransformForPostIncUse(Kind, AR->getStepRecurrence(SE),
- User, OperandValToReplace, Loops, SE, DT);
+ TransformSubExpr(AR->getStepRecurrence(SE),
+ User, OperandValToReplace);
Result = SE.getMinusSCEV(Result, TransformedStep);
}
#if 0
// See the comment on the assert above.
- assert(S == TransformForPostIncUse(Denormalize, Result,
- User, OperandValToReplace,
- Loops, SE, DT) &&
+ assert(S == TransformSubExpr(Result, User, OperandValToReplace) &&
"SCEV normalization is not invertible!");
#endif
break;
@@ -150,8 +164,7 @@
for (SCEVNAryExpr::op_iterator I = X->op_begin(), E = X->op_end();
I != E; ++I) {
const SCEV *O = *I;
- const SCEV *N = TransformForPostIncUse(Kind, O, User, OperandValToReplace,
- Loops, SE, DT);
+ const SCEV *N = TransformSubExpr(O, User, OperandValToReplace);
Changed |= N != O;
Operands.push_back(N);
}
@@ -170,10 +183,8 @@
if (const SCEVUDivExpr *X = dyn_cast<SCEVUDivExpr>(S)) {
const SCEV *LO = X->getLHS();
const SCEV *RO = X->getRHS();
- const SCEV *LN = TransformForPostIncUse(Kind, LO, User, OperandValToReplace,
- Loops, SE, DT);
- const SCEV *RN = TransformForPostIncUse(Kind, RO, User, OperandValToReplace,
- Loops, SE, DT);
+ const SCEV *LN = TransformSubExpr(LO, User, OperandValToReplace);
+ const SCEV *RN = TransformSubExpr(RO, User, OperandValToReplace);
if (LO != LN || RO != RN)
return SE.getUDivExpr(LN, RN);
return S;
@@ -182,3 +193,32 @@
llvm_unreachable("Unexpected SCEV kind!");
return 0;
}
+
+/// Manage recursive transformation across an expression DAG. Revisiting
+/// expressions would lead to exponential recursion.
+const SCEV *PostIncTransform::
+TransformSubExpr(const SCEV *S, Instruction *User, Value *OperandValToReplace) {
+
+ if (isa<SCEVConstant>(S) || isa<SCEVUnknown>(S))
+ return S;
+
+ const SCEV *&ExprRef = Transformed[S];
+ if (ExprRef)
+ return ExprRef;
+
+ ExprRef = TransformImpl(S, User, OperandValToReplace);
+ return ExprRef;
+}
+
+/// Top level driver for transforming an expression DAG into its requested
+/// post-inc form (either "Normalized" or "Denormalized".
+const SCEV *llvm::TransformForPostIncUse(TransformKind Kind,
+ const SCEV *S,
+ Instruction *User,
+ Value *OperandValToReplace,
+ PostIncLoopSet &Loops,
+ ScalarEvolution &SE,
+ DominatorTree &DT) {
+ PostIncTransform Transform(Kind, Loops, SE, DT);
+ return Transform.TransformSubExpr(S, User, OperandValToReplace);
+}
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