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Fix fairly severe bug in my last checking where we treated all unfoldable 

constants as being "true" when evaluating branches.  This was introduced
because we now create constantexprs for the constants instead of failing the
fold.

llvm-svn: 10778
This commit is contained in:
Chris Lattner 2004-01-12 17:40:36 +00:00
parent 4bb9bc3a65
commit fe992d4332
1 changed files with 12 additions and 3 deletions
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15
llvm/lib/Transforms/Scalar/SCCP.cpp
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@ -362,8 +362,10 @@ void SCCP::getFeasibleSuccessors(TerminatorInst &TI, std::vector<bool> &Succs) {
Succs[0] = true;
} else {
InstVal &BCValue = getValueState(BI->getCondition());
if (BCValue.isOverdefined()) {
// Overdefined condition variables mean the branch could go either way.
if (BCValue.isOverdefined() ||
(BCValue.isConstant() && !isa<ConstantBool>(BCValue.getConstant()))) {
// Overdefined condition variables, and branches on unfoldable constant
// conditions, mean the branch could go either way.
Succs[0] = Succs[1] = true;
} else if (BCValue.isConstant()) {
// Constant condition variables mean the branch can only go a single way
@ -375,7 +377,8 @@ void SCCP::getFeasibleSuccessors(TerminatorInst &TI, std::vector<bool> &Succs) {
Succs[0] = Succs[1] = true;
} else if (SwitchInst *SI = dyn_cast<SwitchInst>(&TI)) {
InstVal &SCValue = getValueState(SI->getCondition());
if (SCValue.isOverdefined()) { // Overdefined condition?
if (SCValue.isOverdefined() || // Overdefined condition?
(SCValue.isConstant() && !isa<ConstantInt>(SCValue.getConstant()))) {
// All destinations are executable!
Succs.assign(TI.getNumSuccessors(), true);
} else if (SCValue.isConstant()) {
@ -419,6 +422,9 @@ bool SCCP::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
// Overdefined condition variables mean the branch could go either way.
return true;
} else if (BCValue.isConstant()) {
// Not branching on an evaluatable constant?
if (!isa<ConstantBool>(BCValue.getConstant())) return true;
// Constant condition variables mean the branch can only go a single way
return BI->getSuccessor(BCValue.getConstant() ==
ConstantBool::False) == To;
@ -435,6 +441,9 @@ bool SCCP::isEdgeFeasible(BasicBlock *From, BasicBlock *To) {
return true;
} else if (SCValue.isConstant()) {
Constant *CPV = SCValue.getConstant();
if (!isa<ConstantInt>(CPV))
return true; // not a foldable constant?
// Make sure to skip the "default value" which isn't a value
for (unsigned i = 1, E = SI->getNumSuccessors(); i != E; ++i)
if (SI->getSuccessorValue(i) == CPV) // Found the taken branch...