Add support for br/brcond/switch and phi
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23439 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/IPO/GlobalOpt.cpp b/lib/Transforms/IPO/GlobalOpt.cpp
index b9625fe..abef0db 100644
--- a/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/lib/Transforms/IPO/GlobalOpt.cpp
@@ -1274,8 +1274,14 @@
/// 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 @@
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.