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

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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@10778 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-01-12 17:40:36 +00:00
parent d56147dc72
commit 84831642e4
1 changed files with 12 additions and 3 deletions
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15
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...