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allow demotion to volatile values, add support for invoke 

llvm-svn: 23473
This commit is contained in:
Chris Lattner 2005-09-27 19:39:00 +00:00
parent cce0355fc0
commit 16cd356fb2
1 changed files with 15 additions and 12 deletions
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27
llvm/lib/Transforms/Utils/DemoteRegToStack.cpp
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@ -29,7 +29,7 @@ using namespace llvm;
/// invalidating the SSA information for the value. It returns the pointer to
/// the alloca inserted to create a stack slot for I.
///
AllocaInst* llvm::DemoteRegToStack(Instruction &I) {
AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads) {
if (I.use_empty()) return 0; // nothing to do!
// Create a stack slot to hold the value.
@ -57,7 +57,7 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I) {
Value *&V = Loads[PN->getIncomingBlock(i)];
if (V == 0) {
// Insert the load into the predecessor block
V = new LoadInst(Slot, I.getName()+".reload",
V = new LoadInst(Slot, I.getName()+".reload", VolatileLoads,
PN->getIncomingBlock(i)->getTerminator());
}
PN->setIncomingValue(i, V);
@ -65,7 +65,7 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I) {
} else {
// If this is a normal instruction, just insert a load.
Value *V = new LoadInst(Slot, I.getName()+".reload", U);
Value *V = new LoadInst(Slot, I.getName()+".reload", VolatileLoads, U);
U->replaceUsesOfWith(&I, V);
}
}
@ -74,18 +74,21 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I) {
// Insert stores of the computed value into the stack slot. We have to be
// careful is I is an invoke instruction though, because we can't insert the
// store AFTER the terminator instruction.
BasicBlock::iterator InsertPt;
if (!isa<TerminatorInst>(I)) {
BasicBlock::iterator InsertPt = &I;
for (++InsertPt; isa<PHINode>(InsertPt); ++InsertPt)
/* empty */; // Don't insert before any PHI nodes.
new StoreInst(&I, Slot, InsertPt);
InsertPt = &I;
} else {
// FIXME: We cannot yet demote invoke instructions to the stack, because
// doing so would require breaking critical edges. This should be fixed
// eventually.
assert(0 &&
"Cannot demote the value computed by an invoke instruction yet!");
// We cannot demote invoke instructions to the stack if their normal edge
// is critical.
InvokeInst &II = cast<InvokeInst>(I);
assert(II.getNormalDest()->getSinglePredecessor() &&
"Cannot demote invoke with a critical successor!");
InsertPt = II.getNormalDest()->begin();
}
for (++InsertPt; isa<PHINode>(InsertPt); ++InsertPt)
/* empty */; // Don't insert before any PHI nodes.
new StoreInst(&I, Slot, InsertPt);
return Slot;
}