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Convert non-address taken functions with C calling conventions to fastcc.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21791 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2005-05-08 22:18:06 +00:00
parent 56c418676a
commit fb217adf92
1 changed files with 41 additions and 1 deletions
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42
lib/Transforms/IPO/GlobalOpt.cpp
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@ -15,6 +15,7 @@
#define DEBUG_TYPE "globalopt"
#include "llvm/Transforms/IPO.h"
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Instructions.h"
@ -42,6 +43,8 @@ namespace {
Statistic<> NumLocalized("globalopt", "Number of globals localized");
Statistic<> NumShrunkToBool("globalopt",
"Number of global vars shrunk to booleans");
Statistic<> NumFastCallFns("globalopt",
"Number of functions converted to fastcc");
struct GlobalOpt : public ModulePass {
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
@ -1039,6 +1042,32 @@ bool GlobalOpt::ProcessInternalGlobal(GlobalVariable *GV,
return false;
}
/// OnlyCalledDirectly - Return true if the specified function is only called
/// directly. In other words, its address is never taken.
static bool OnlyCalledDirectly(Function *F) {
for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
Instruction *User = dyn_cast<Instruction>(*UI);
if (!User) return false;
if (!isa<CallInst>(User) && !isa<InvokeInst>(User)) return false;
// See if the function address is passed as an argument.
for (unsigned i = 1, e = User->getNumOperands(); i != e; ++i)
if (User->getOperand(i) == F) return false;
}
return true;
}
/// ChangeCalleesToFastCall - Walk all of the direct calls of the specified
/// function, changing them to FastCC.
static void ChangeCalleesToFastCall(Function *F) {
for (Value::use_iterator UI = F->use_begin(), E = F->use_end(); UI != E;++UI){
Instruction *User = cast<Instruction>(*UI);
if (CallInst *CI = dyn_cast<CallInst>(User))
CI->setCallingConv(CallingConv::Fast);
else
cast<InvokeInst>(User)->setCallingConv(CallingConv::Fast);
}
}
bool GlobalOpt::runOnModule(Module &M) {
bool Changed = false;
@ -1055,6 +1084,16 @@ bool GlobalOpt::runOnModule(Module &M) {
M.getFunctionList().erase(F);
LocalChange = true;
++NumFnDeleted;
} else if (F->hasInternalLinkage() &&
F->getCallingConv() == CallingConv::C && !F->isVarArg() &&
OnlyCalledDirectly(F)) {
// If this function has C calling conventions, is not a varargs
// function, and is only called directly, promote it to use the Fast
// calling convention.
F->setCallingConv(CallingConv::Fast);
ChangeCalleesToFastCall(F);
++NumFastCallFns;
LocalChange = true;
}
}
Changed |= LocalChange;
@ -1063,7 +1102,8 @@ bool GlobalOpt::runOnModule(Module &M) {
LocalChange = true;
while (LocalChange) {
LocalChange = false;
for (Module::global_iterator GVI = M.global_begin(), E = M.global_end(); GVI != E;) {
for (Module::global_iterator GVI = M.global_begin(), E = M.global_end();
GVI != E; ) {
GlobalVariable *GV = GVI++;
if (!GV->isConstant() && GV->hasInternalLinkage() &&
GV->hasInitializer())