llvm-6502/lib/Transforms/IPO/InlineAlways.cpp
Bob Wilson 28f872f8a1 Clean up handling of always-inline functions in the inliner.
This patch moves the isInlineViable function from the InlineAlways pass into
the InlineCostAnalyzer and then changes the InlineCost computation to use that
simple check for always-inline functions. All the special-case checks for
AlwaysInline in the CallAnalyzer can then go away.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168300 91177308-0d34-0410-b5e6-96231b3b80d8
2012-11-19 07:04:35 +00:00

99 lines
3.7 KiB
C++

//===- InlineAlways.cpp - Code to inline always_inline functions ----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements a custom inliner that handles only functions that
// are marked as "always inline".
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "inline"
#include "llvm/CallingConv.h"
#include "llvm/Instructions.h"
#include "llvm/IntrinsicInst.h"
#include "llvm/Module.h"
#include "llvm/Type.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Analysis/InlineCost.h"
#include "llvm/Support/CallSite.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/InlinerPass.h"
#include "llvm/DataLayout.h"
#include "llvm/ADT/SmallPtrSet.h"
using namespace llvm;
namespace {
// AlwaysInliner only inlines functions that are mark as "always inline".
class AlwaysInliner : public Inliner {
InlineCostAnalyzer CA;
public:
// Use extremely low threshold.
AlwaysInliner() : Inliner(ID, -2000000000, /*InsertLifetime*/true) {
initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
}
AlwaysInliner(bool InsertLifetime) : Inliner(ID, -2000000000,
InsertLifetime) {
initializeAlwaysInlinerPass(*PassRegistry::getPassRegistry());
}
static char ID; // Pass identification, replacement for typeid
virtual InlineCost getInlineCost(CallSite CS);
virtual bool doFinalization(CallGraph &CG) {
return removeDeadFunctions(CG, /*AlwaysInlineOnly=*/true);
}
virtual bool doInitialization(CallGraph &CG);
};
}
char AlwaysInliner::ID = 0;
INITIALIZE_PASS_BEGIN(AlwaysInliner, "always-inline",
"Inliner for always_inline functions", false, false)
INITIALIZE_AG_DEPENDENCY(CallGraph)
INITIALIZE_PASS_END(AlwaysInliner, "always-inline",
"Inliner for always_inline functions", false, false)
Pass *llvm::createAlwaysInlinerPass() { return new AlwaysInliner(); }
Pass *llvm::createAlwaysInlinerPass(bool InsertLifetime) {
return new AlwaysInliner(InsertLifetime);
}
/// \brief Get the inline cost for the always-inliner.
///
/// The always inliner *only* handles functions which are marked with the
/// attribute to force inlining. As such, it is dramatically simpler and avoids
/// using the powerful (but expensive) inline cost analysis. Instead it uses
/// a very simple and boring direct walk of the instructions looking for
/// impossible-to-inline constructs.
///
/// Note, it would be possible to go to some lengths to cache the information
/// computed here, but as we only expect to do this for relatively few and
/// small functions which have the explicit attribute to force inlining, it is
/// likely not worth it in practice.
InlineCost AlwaysInliner::getInlineCost(CallSite CS) {
Function *Callee = CS.getCalledFunction();
// Only inline direct calls to functions with always-inline attributes
// that are viable for inlining. FIXME: We shouldn't even get here for
// declarations.
if (Callee && !Callee->isDeclaration() &&
Callee->getFnAttributes().hasAttribute(Attributes::AlwaysInline) &&
CA.isInlineViable(*Callee))
return InlineCost::getAlways();
return InlineCost::getNever();
}
// doInitialization - Initializes the vector of functions that have not
// been annotated with the "always inline" attribute.
bool AlwaysInliner::doInitialization(CallGraph &CG) {
CA.setDataLayout(getAnalysisIfAvailable<DataLayout>());
return false;
}