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Let DAE keep a list of live functions, instead of simply marking all arguments

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and return values live for those functions. This doesn't change anything yet,
but prepares for the coming commits.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53601 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Matthijs Kooijman 2008-07-15 09:11:16 +00:00
parent 3015652473
commit 2bf5372d8a
1 changed files with 14 additions and 6 deletions
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20
lib/Transforms/IPO/DeadArgumentElimination.cpp
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@ -110,9 +110,12 @@ namespace {
UseMap Uses;
typedef std::set<RetOrArg> LiveSet;
typedef std::set<const Function*> LiveFuncSet;
/// This set contains all values that have been determined to be live.
LiveSet LiveValues;
/// This set contains all values that are cannot be changed in any way.
LiveFuncSet LiveFunctions;
typedef SmallVector<RetOrArg, 5> UseVector;
@ -291,8 +294,8 @@ static unsigned NumRetVals(const Function *F) {
/// live, it adds Use to the MaybeLiveUses argument. Returns the determined
/// liveness of Use.
DAE::Liveness DAE::MarkIfNotLive(RetOrArg Use, UseVector &MaybeLiveUses) {
// We're live if our use is already marked as live.
if (LiveValues.count(Use))
// We're live if our use or its Function is already marked as live.
if (LiveFunctions.count(Use.F) || LiveValues.count(Use))
return Live;
// We're maybe live otherwise, but remember that we must become live if
@ -530,18 +533,23 @@ void DAE::MarkValue(const RetOrArg &RA, Liveness L,
/// values (according to Uses) live as well.
void DAE::MarkLive(const Function &F) {
DOUT << "DAE - Intrinsically live fn: " << F.getName() << "\n";
// Mark the function as live.
LiveFunctions.insert(&F);
// Mark all arguments as live.
for (unsigned i = 0, e = F.arg_size(); i != e; ++i)
MarkLive(CreateArg(&F, i));
PropagateLiveness(CreateArg(&F, i));
// Mark all return values as live.
for (unsigned i = 0, e = NumRetVals(&F); i != e; ++i)
MarkLive(CreateRet(&F, i));
PropagateLiveness(CreateRet(&F, i));
}
/// MarkLive - Mark the given return value or argument as live. Additionally,
/// mark any values that are used by this value (according to Uses) live as
/// well.
void DAE::MarkLive(const RetOrArg &RA) {
if (LiveFunctions.count(RA.F))
return; // Function was already marked Live.
if (!LiveValues.insert(RA).second)
return; // We were already marked Live.
@ -571,8 +579,8 @@ void DAE::PropagateLiveness(const RetOrArg &RA) {
// the function to not have these arguments and return values.
//
bool DAE::RemoveDeadStuffFromFunction(Function *F) {
// Quick exit path for external functions
if (!F->hasInternalLinkage() && (!ShouldHackArguments() || F->isIntrinsic()))
// Don't modify fully live functions
if (LiveFunctions.count(F))
return false;
// Start by computing a new prototype for the function, which is the same as