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This patch makes the inliner refuse to inline functions that have alloca

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instructions in the body of the function (not the entry block).  This fixes
test/Programs/SingleSource/Regression/C/2004-08-12-InlinerAndAllocas.c
and test/Programs/External/SPEC/CINT2000/176.gcc on zion.

This should obviously be pulled into 1.3.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@15684 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2004-08-12 05:45:09 +00:00
parent a1b6ae9d7c
commit ee45f4cbe4
1 changed files with 57 additions and 25 deletions
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82
lib/Transforms/IPO/InlineSimple.cpp
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@ -31,6 +31,16 @@ namespace {
// FunctionInfo - For each function, calculate the size of it in blocks and
// instructions.
struct FunctionInfo {
// HasAllocas - Keep track of whether or not a function contains an alloca
// instruction that is not in the entry block of the function. Inlining
// this call could cause us to blow out the stack, because the stack memory
// would never be released.
//
// FIXME: LLVM needs a way of dealloca'ing memory, which would make this
// irrelevant!
//
bool HasAllocas;
// NumInsts, NumBlocks - Keep track of how large each function is, which is
// used to estimate the code size cost of inlining it.
unsigned NumInsts, NumBlocks;
@ -41,7 +51,11 @@ namespace {
// entry here.
std::vector<ArgInfo> ArgumentWeights;
FunctionInfo() : NumInsts(0), NumBlocks(0) {}
FunctionInfo() : HasAllocas(false), NumInsts(0), NumBlocks(0) {}
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
void analyzeFunction(Function *F);
};
class SimpleInliner : public Inliner {
@ -123,6 +137,41 @@ static unsigned CountCodeReductionForAlloca(Value *V) {
return Reduction;
}
/// analyzeFunction - Fill in the current structure with information gleaned
/// from the specified function.
void FunctionInfo::analyzeFunction(Function *F) {
unsigned NumInsts = 0, NumBlocks = 0;
// Look at the size of the callee. Each basic block counts as 20 units, and
// each instruction counts as 10.
for (Function::const_iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
for (BasicBlock::const_iterator II = BB->begin(), E = BB->end();
II != E; ++II) {
++NumInsts;
// If there is an alloca in the body of the function, we cannot currently
// inline the function without the risk of exploding the stack.
if (isa<AllocaInst>(II) && BB != F->begin()) {
HasAllocas = true;
this->NumBlocks = this->NumInsts = 1;
return;
}
}
++NumBlocks;
}
this->NumBlocks = NumBlocks;
this->NumInsts = NumInsts;
// Check out all of the arguments to the function, figuring out how much
// code can be eliminated if one of the arguments is a constant.
for (Function::aiterator I = F->abegin(), E = F->aend(); I != E; ++I)
ArgumentWeights.push_back(ArgInfo(CountCodeReductionForConstant(I),
CountCodeReductionForAlloca(I)));
}
// getInlineCost - The heuristic used to determine if we should inline the
// function call or not.
//
@ -149,31 +198,14 @@ int SimpleInliner::getInlineCost(CallSite CS) {
// Get information about the callee...
FunctionInfo &CalleeFI = CachedFunctionInfo[Callee];
// If we haven't calculated this information yet...
if (CalleeFI.NumBlocks == 0) {
unsigned NumInsts = 0, NumBlocks = 0;
// Look at the size of the callee. Each basic block counts as 20 units, and
// each instruction counts as 10.
for (Function::const_iterator BB = Callee->begin(), E = Callee->end();
BB != E; ++BB) {
NumInsts += BB->size();
NumBlocks++;
}
CalleeFI.NumBlocks = NumBlocks;
CalleeFI.NumInsts = NumInsts;
// Check out all of the arguments to the function, figuring out how much
// code can be eliminated if one of the arguments is a constant.
std::vector<ArgInfo> &ArgWeights = CalleeFI.ArgumentWeights;
for (Function::aiterator I = Callee->abegin(), E = Callee->aend();
I != E; ++I)
ArgWeights.push_back(ArgInfo(CountCodeReductionForConstant(I),
CountCodeReductionForAlloca(I)));
}
// If we haven't calculated this information yet, do so now.
if (CalleeFI.NumBlocks == 0)
CalleeFI.analyzeFunction(Callee);
// Don't inline calls to functions with allocas that are not in the entry
// block of the function.
if (CalleeFI.HasAllocas)
return 2000000000;
// Add to the inline quality for properties that make the call valuable to
// inline. This includes factors that indicate that the result of inlining