mirror of
https://github.com/c64scene-ar/llvm-6502.git
synced 2025-10-30 16:17:05 +00:00
237ef567f6
* Separate the policy decisions into a derived class [InlineSimple]
* Move the inlining mechanics into a base class [Inliner]
* Change the inliner to be an SCCPass, making it more structured and
eventually pipelinable with other SCC passes
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@8257 91177308-0d34-0410-b5e6-96231b3b80d8
90 lines
3.3 KiB
C++
90 lines
3.3 KiB
C++
//===- InlineSimple.cpp - Code to perform simple function inlining --------===//
|
|
//
|
|
// This file implements bottom-up inlining of functions into callees.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "Inliner.h"
|
|
#include "llvm/Function.h"
|
|
#include "llvm/iMemory.h"
|
|
#include "llvm/Support/CallSite.h"
|
|
#include "llvm/Transforms/IPO.h"
|
|
|
|
namespace {
|
|
struct SimpleInliner : public Inliner {
|
|
int getInlineCost(CallSite CS);
|
|
};
|
|
RegisterOpt<SimpleInliner> X("inline", "Function Integration/Inlining");
|
|
}
|
|
|
|
Pass *createFunctionInliningPass() { return new SimpleInliner(); }
|
|
|
|
|
|
// getInlineCost - The heuristic used to determine if we should inline the
|
|
// function call or not.
|
|
//
|
|
int SimpleInliner::getInlineCost(CallSite CS) {
|
|
Instruction *TheCall = CS.getInstruction();
|
|
const Function *Callee = CS.getCalledFunction();
|
|
const Function *Caller = TheCall->getParent()->getParent();
|
|
|
|
// Don't inline a directly recursive call.
|
|
if (Caller == Callee) return 2000000000;
|
|
|
|
// InlineCost - This value measures how good of an inline candidate this call
|
|
// site is to inline. A lower inline cost make is more likely for the call to
|
|
// be inlined. This value may go negative.
|
|
//
|
|
int InlineCost = 0;
|
|
|
|
// If there is only one call of the function, and it has internal linkage,
|
|
// make it almost guaranteed to be inlined.
|
|
//
|
|
if (Callee->use_size() == 1 && Callee->hasInternalLinkage())
|
|
InlineCost -= 30000;
|
|
|
|
// Add to the inline quality for properties that make the call valueable to
|
|
// inline. This includes factors that indicate that the result of inlining
|
|
// the function will be optimizable. Currently this just looks at arguments
|
|
// passed into the function.
|
|
//
|
|
for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end();
|
|
I != E; ++I) {
|
|
// Each argument passed in has a cost at both the caller and the callee
|
|
// sides. This favors functions that take many arguments over functions
|
|
// that take few arguments.
|
|
InlineCost -= 20;
|
|
|
|
// If this is a function being passed in, it is very likely that we will be
|
|
// able to turn an indirect function call into a direct function call.
|
|
if (isa<Function>(I))
|
|
InlineCost -= 100;
|
|
|
|
// If a constant, global variable or alloca is passed in, inlining this
|
|
// function is likely to allow significant future optimization possibilities
|
|
// (constant propagation, scalar promotion, and scalarization), so encourage
|
|
// the inlining of the function.
|
|
//
|
|
else if (isa<Constant>(I) || isa<GlobalVariable>(I) || isa<AllocaInst>(I))
|
|
InlineCost -= 60;
|
|
}
|
|
|
|
// Now that we have considered all of the factors that make the call site more
|
|
// likely to be inlined, look at factors that make us not want to inline it.
|
|
// As soon as the inline quality gets negative, bail out.
|
|
|
|
// 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)
|
|
InlineCost += BB->size()*10 + 20;
|
|
|
|
// Don't inline into something too big, which would make it bigger. Here, we
|
|
// count each basic block as a single unit.
|
|
for (Function::const_iterator BB = Caller->begin(), E = Caller->end();
|
|
BB != E; ++BB)
|
|
InlineCost++;
|
|
|
|
return InlineCost;
|
|
}
|