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Add support for br/brcond/switch and phi

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23439 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-09-26 04:57:38 +00:00
parent 44b19f2bcb
commit cdf98bed96
1 changed files with 47 additions and 3 deletions
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50
lib/Transforms/IPO/GlobalOpt.cpp
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@ -1274,8 +1274,14 @@ static bool EvaluateStaticConstructor(Function *F) {
/// this state is committed to the process.
std::map<Constant*, Constant*> MutatedMemory;
/// ExecutedBlocks - We only handle non-looping, non-recursive code. As such,
/// we can only evaluate any one basic block at most once. This set keeps
/// track of what we have executed so we can detect recursive cases etc.
std::set<BasicBlock*> ExecutedBlocks;
// CurInst - The current instruction we're evaluating.
BasicBlock::iterator CurInst = F->begin()->begin();
ExecutedBlocks.insert(F->begin());
// This is the main evaluation loop.
while (1) {
@ -1303,9 +1309,47 @@ static bool EvaluateStaticConstructor(Function *F) {
InstResult = ConstantExpr::getSelect(getVal(Values, SI->getOperand(0)),
getVal(Values, SI->getOperand(1)),
getVal(Values, SI->getOperand(2)));
} else if (ReturnInst *RI = dyn_cast<ReturnInst>(CurInst)) {
assert(RI->getNumOperands() == 0);
break; // We succeeded at evaluating this ctor!
} else if (TerminatorInst *TI = dyn_cast<TerminatorInst>(CurInst)) {
BasicBlock *NewBB = 0;
if (BranchInst *BI = dyn_cast<BranchInst>(CurInst)) {
if (BI->isUnconditional()) {
NewBB = BI->getSuccessor(0);
} else {
ConstantBool *Cond =
dyn_cast<ConstantBool>(getVal(Values, BI->getCondition()));
if (!Cond) return false; // Cannot determine.
NewBB = BI->getSuccessor(!Cond->getValue());
}
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(CurInst)) {
ConstantInt *Val =
dyn_cast<ConstantInt>(getVal(Values, SI->getCondition()));
if (!Val) return false; // Cannot determine.
NewBB = SI->getSuccessor(SI->findCaseValue(Val));
} else if (ReturnInst *RI = dyn_cast<ReturnInst>(CurInst)) {
assert(RI->getNumOperands() == 0);
break; // We succeeded at evaluating this ctor!
} else {
// unwind, unreachable.
return false; // Cannot handle this terminator.
}
// Okay, we succeeded in evaluating this control flow. See if we have
// executed the new block before. If so, we have a looping or recursive
// function, which we cannot evaluate in reasonable time.
if (!ExecutedBlocks.insert(NewBB).second)
return false; // Recursed!
// Okay, we have never been in this block before. Check to see if there
// are any PHI nodes. If so, evaluate them with information about where
// we came from.
BasicBlock *OldBB = CurInst->getParent();
CurInst = NewBB->begin();
PHINode *PN;
for (; (PN = dyn_cast<PHINode>(CurInst)); ++CurInst)
Values[PN] = getVal(Values, PN->getIncomingValueForBlock(OldBB));
// Do NOT increment CurInst. We know that the terminator had no value.
continue;
} else {
// TODO: use ConstantFoldCall for function calls.