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Optimize MachineBasicBlock::getSymbol by caching the symbol. Since the symbol

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name computation is expensive, this helps save about 25% of the time spent in
this function.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@180049 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Eli Bendersky 2013-04-22 21:21:08 +00:00
parent 0af5493701
commit 2ad047e04d
2 changed files with 15 additions and 8 deletions
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5
include/llvm/CodeGen/MachineBasicBlock.h
View File

@ -71,7 +71,6 @@ class MachineBasicBlock : public ilist_node<MachineBasicBlock> {
std::vector<MachineBasicBlock *> Predecessors;
std::vector<MachineBasicBlock *> Successors;
/// Weights - Keep track of the weights to the successors. This vector
/// has the same order as Successors, or it is empty if we don't use it
/// (disable optimization).
@ -96,6 +95,10 @@ class MachineBasicBlock : public ilist_node<MachineBasicBlock> {
/// target of an indirect branch.
bool AddressTaken;
/// \brief since getSymbol is a relatively heavy-weight operation, the symbol
/// is only computed once and is cached.
mutable MCSymbol *CachedMCSymbol;
// Intrusive list support
MachineBasicBlock() {}

18
lib/CodeGen/MachineBasicBlock.cpp
View File

@ -37,7 +37,7 @@ using namespace llvm;
MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb)
: BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false),
AddressTaken(false) {
AddressTaken(false), CachedMCSymbol(NULL) {
Insts.Parent = this;
}
@ -48,12 +48,16 @@ MachineBasicBlock::~MachineBasicBlock() {
/// getSymbol - Return the MCSymbol for this basic block.
///
MCSymbol *MachineBasicBlock::getSymbol() const {
const MachineFunction *MF = getParent();
MCContext &Ctx = MF->getContext();
const char *Prefix = Ctx.getAsmInfo().getPrivateGlobalPrefix();
return Ctx.GetOrCreateSymbol(Twine(Prefix) + "BB" +
Twine(MF->getFunctionNumber()) + "_" +
Twine(getNumber()));
if (!CachedMCSymbol) {
const MachineFunction *MF = getParent();
MCContext &Ctx = MF->getContext();
const char *Prefix = Ctx.getAsmInfo().getPrivateGlobalPrefix();
CachedMCSymbol = Ctx.GetOrCreateSymbol(Twine(Prefix) + "BB" +
Twine(MF->getFunctionNumber()) +
"_" + Twine(getNumber()));
}
return CachedMCSymbol;
}