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* Refactor some code into a new BasedUser::RewriteInstructionToUseNewBase

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method.
* Fix a crash on 178.galgel, where we would insert expressions before PHI
  nodes instead of into the PHI node predecessor blocks.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22657 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-08-04 20:03:32 +00:00
parent 763103c87d
commit 2114b273ef
1 changed files with 48 additions and 16 deletions
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64
lib/Transforms/Scalar/LoopStrengthReduce.cpp
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@ -356,6 +356,10 @@ namespace {
BasedUser(Instruction *I, Value *Op, const SCEVHandle &IMM)
: Inst(I), OperandValToReplace(Op), Imm(IMM), EmittedBase(0) {}
// Once we rewrite the code to insert the new IVs we want, update the
// operands of Inst to use the new expression 'NewBase', with 'Imm' added
// to it.
void RewriteInstructionToUseNewBase(Value *NewBase, SCEVExpander &Rewriter);
// No need to compare these.
bool operator<(const BasedUser &BU) const { return 0; }
@ -372,6 +376,45 @@ void BasedUser::dump() const {
std::cerr << " Inst: " << *Inst;
}
// Once we rewrite the code to insert the new IVs we want, update the
// operands of Inst to use the new expression 'NewBase', with 'Imm' added
// to it.
void BasedUser::RewriteInstructionToUseNewBase(Value *NewBase,
SCEVExpander &Rewriter) {
if (!isa<PHINode>(Inst)) {
SCEVHandle NewValSCEV = SCEVAddExpr::get(SCEVUnknown::get(NewBase), Imm);
Value *NewVal = Rewriter.expandCodeFor(NewValSCEV, Inst,
OperandValToReplace->getType());
// Replace the use of the operand Value with the new Phi we just created.
Inst->replaceUsesOfWith(OperandValToReplace, NewVal);
DEBUG(std::cerr << " CHANGED: IMM =" << *Imm << " Inst = " << *Inst);
return;
}
// PHI nodes are more complex. We have to insert one copy of the NewBase+Imm
// expression into each operand block that uses it.
PHINode *PN = cast<PHINode>(Inst);
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
if (PN->getIncomingValue(i) == OperandValToReplace) {
// FIXME: this should split any critical edges.
// Insert the code into the end of the predecessor block.
BasicBlock::iterator InsertPt = PN->getIncomingBlock(i)->getTerminator();
SCEVHandle NewValSCEV = SCEVAddExpr::get(SCEVUnknown::get(NewBase), Imm);
Value *NewVal = Rewriter.expandCodeFor(NewValSCEV, InsertPt,
OperandValToReplace->getType());
// Replace the use of the operand Value with the new Phi we just created.
PN->setIncomingValue(i, NewVal);
Rewriter.clear();
}
}
DEBUG(std::cerr << " CHANGED: IMM =" << *Imm << " Inst = " << *Inst);
}
/// isTargetConstant - Return true if the following can be referenced by the
/// immediate field of a target instruction.
static bool isTargetConstant(const SCEVHandle &V) {
@ -526,20 +569,14 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(Value *Stride,
// Clear the SCEVExpander's expression map so that we are guaranteed
// to have the code emitted where we expect it.
Rewriter.clear();
SCEVHandle NewValSCEV = SCEVAddExpr::get(SCEVUnknown::get(NewPHI),
User.Imm);
Value *Replaced = User.OperandValToReplace;
Value *newVal = Rewriter.expandCodeFor(NewValSCEV, User.Inst,
Replaced->getType());
// Replace the use of the operand Value with the new Phi we just created.
User.Inst->replaceUsesOfWith(Replaced, newVal);
DEBUG(std::cerr << " CHANGED: IMM =" << *User.Imm << " Inst = "
<< *User.Inst);
// Now that we know what we need to do, insert code before User for the
// immediate and any loop-variant expressions.
User.RewriteInstructionToUseNewBase(NewPHI, Rewriter);
// Mark old value we replaced as possibly dead, so that it is elminated
// if we just replaced the last use of that value.
DeadInsts.insert(cast<Instruction>(Replaced));
DeadInsts.insert(cast<Instruction>(User.OperandValToReplace));
UsersToProcess.erase(UsersToProcess.begin());
++NumReduced;
@ -549,11 +586,6 @@ void LoopStrengthReduce::StrengthReduceStridedIVUsers(Value *Stride,
// IMPORTANT TODO: Figure out how to partition the IV's with this stride, but
// different starting values, into different PHIs.
// BEFORE writing this, it's probably useful to handle GEP's.
// NOTE: pull all constants together, for REG+IMM addressing, include &GV in
// 'IMM' if the target supports it.
}