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Record CodeGen optimization level in the BranchFolding pass so that we can

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use it to control tail merging when there is a tradeoff between performance
and code size.  When there is only 1 instruction in the common tail, we have
been merging.  That can be good for code size but is a definite loss for
performance.  Now we will avoid tail merging in that case when the
optimization level is "Aggressive", i.e., "-O3".  Radar 7338114.

Since the IfConversion pass invokes BranchFolding, it too needs to know
the optimization level.  Note that I removed the RegisterPass instantiation
for IfConversion because it required a default constructor.  If someone
wants to keep that for some reason, we can add a default constructor with
a hard-wired optimization level.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@85346 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Bob Wilson
2009-10-27 23:49:38 +00:00
parent 03236140fa
commit cd4f04d6bc
6 changed files with 29 additions and 19 deletions
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13
lib/CodeGen/IfConversion.cpp
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@ -148,9 +148,11 @@ namespace {
const TargetInstrInfo *TII;
bool MadeChange;
int FnNum;
CodeGenOpt::Level OptLevel;
public:
static char ID;
IfConverter() : MachineFunctionPass(&ID), FnNum(-1) {}
IfConverter(CodeGenOpt::Level OL) :
MachineFunctionPass(&ID), FnNum(-1), OptLevel(OL) {}
virtual bool runOnMachineFunction(MachineFunction &MF);
virtual const char *getPassName() const { return "If Converter"; }
@ -219,10 +221,9 @@ namespace {
char IfConverter::ID = 0;
}
static RegisterPass<IfConverter>
X("if-converter", "If Converter");
FunctionPass *llvm::createIfConverterPass() { return new IfConverter(); }
FunctionPass *llvm::createIfConverterPass(CodeGenOpt::Level OptLevel) {
return new IfConverter(OptLevel);
}
bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
TLI = MF.getTarget().getTargetLowering();
@ -362,7 +363,7 @@ bool IfConverter::runOnMachineFunction(MachineFunction &MF) {
BBAnalysis.clear();
if (MadeChange) {
BranchFolder BF(false);
BranchFolder BF(false, OptLevel);
BF.OptimizeFunction(MF, TII,
MF.getTarget().getRegisterInfo(),
getAnalysisIfAvailable<MachineModuleInfo>());