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[GISel]: Fix undefined behavior while accessing DefaultAction map 

We end up dereferencing the end iterator here when the Aspect doesn't exist in the DefaultAction map.
Change the API to return Optional<LLT> and return None when not found.
Also update the callers to handle the None case

llvm-svn: 302963
This commit is contained in:
Aditya Nandakumar 2017-05-12 22:43:58 +00:00
parent 12aa9554a6
commit 479ddd20fc
2 changed files with 13 additions and 6 deletions
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17
llvm/include/llvm/CodeGen/GlobalISel/LegalizerInfo.h
View File

@ -145,7 +145,7 @@ public:
/// Iterate the given function (typically something like doubling the width)
/// on Ty until we find a legal type for this operation.
LLT findLegalType(const InstrAspect &Aspect,
Optional<LLT> findLegalType(const InstrAspect &Aspect,
function_ref<LLT(LLT)> NextType) const {
LegalizeAction Action;
const TypeMap &Map = Actions[Aspect.Opcode - FirstOp][Aspect.Idx];
@ -153,8 +153,12 @@ public:
do {
Ty = NextType(Ty);
auto ActionIt = Map.find(Ty);
if (ActionIt == Map.end())
Action = DefaultActions.find(Aspect.Opcode)->second;
if (ActionIt == Map.end()) {
auto DefaultIt = DefaultActions.find(Aspect.Opcode);
if (DefaultIt == DefaultActions.end())
return None;
Action = DefaultIt->second;
}
else
Action = ActionIt->second;
} while(Action != Legal);
@ -163,11 +167,14 @@ public:
/// Find what type it's actually OK to perform the given operation on, given
/// the general approach we've decided to take.
LLT findLegalType(const InstrAspect &Aspect, LegalizeAction Action) const;
Optional<LLT> findLegalType(const InstrAspect &Aspect, LegalizeAction Action) const;
std::pair<LegalizeAction, LLT> findLegalAction(const InstrAspect &Aspect,
LegalizeAction Action) const {
return std::make_pair(Action, findLegalType(Aspect, Action));
auto LegalType = findLegalType(Aspect, Action);
if (!LegalType)
return std::make_pair(LegalizeAction::Unsupported, LLT());
return std::make_pair(Action, *LegalType);
}
/// Find the specified \p Aspect in the primary (explicitly set) Actions

2
llvm/lib/CodeGen/GlobalISel/LegalizerInfo.cpp
View File

@ -162,7 +162,7 @@ bool LegalizerInfo::isLegal(const MachineInstr &MI,
return std::get<0>(getAction(MI, MRI)) == Legal;
}
LLT LegalizerInfo::findLegalType(const InstrAspect &Aspect,
Optional<LLT> LegalizerInfo::findLegalType(const InstrAspect &Aspect,
LegalizeAction Action) const {
switch(Action) {
default: