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[inliner]: Refactor inline deferring logic into its own method /NFC 

The implemented heuristic has a large body of code which better sits
in its own function for better readability. It also allows adding more
heuristics easier in the future.

llvm-svn: 268107
This commit is contained in:
Xinliang David Li 2016-04-29 21:21:44 +00:00
parent 7da9b445ea
commit 1ffa28a3f1
2 changed files with 82 additions and 70 deletions
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4
llvm/include/llvm/Transforms/IPO/InlinerPass.h
View File

@ -69,6 +69,10 @@ private:
/// shouldInline - Return true if the inliner should attempt to
/// inline at the given CallSite.
bool shouldInline(CallSite CS);
/// Return true if inlining of CS can block the caller from being
/// inlined which is proved to be more beneficial. \p IC is the
/// estimated inline cost associated with callsite \p CS.
bool shouldBeDeferred(Function *Caller, CallSite CS, InlineCost IC);
protected:
AssumptionCacheTracker *ACT;

84
llvm/lib/Transforms/IPO/Inliner.cpp
View File

@ -227,38 +227,11 @@ static void emitAnalysis(CallSite CS, const Twine &Msg) {
emitOptimizationRemarkAnalysis(Ctx, DEBUG_TYPE, *Caller, DLoc, Msg);
}
/// Return true if the inliner should attempt to inline at the given CallSite.
bool Inliner::shouldInline(CallSite CS) {
InlineCost IC = getInlineCost(CS);
bool Inliner::shouldBeDeferred(Function *Caller, CallSite CS, InlineCost IC) {
if (IC.isAlways()) {
DEBUG(dbgs() << " Inlining: cost=always"
<< ", Call: " << *CS.getInstruction() << "\n");
emitAnalysis(CS, Twine(CS.getCalledFunction()->getName()) +
" should always be inlined (cost=always)");
return true;
}
if (IC.isNever()) {
DEBUG(dbgs() << " NOT Inlining: cost=never"
<< ", Call: " << *CS.getInstruction() << "\n");
emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
" should never be inlined (cost=never)"));
// For now we only handle local or inline functions.
if (!Caller->hasLocalLinkage() && !Caller->hasLinkOnceODRLinkage())
return false;
}
Function *Caller = CS.getCaller();
if (!IC) {
DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost()
<< ", thres=" << (IC.getCostDelta() + IC.getCost())
<< ", Call: " << *CS.getInstruction() << "\n");
emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
" too costly to inline (cost=") +
Twine(IC.getCost()) + ", threshold=" +
Twine(IC.getCostDelta() + IC.getCost()) + ")");
return false;
}
// Try to detect the case where the current inlining candidate caller (call
// it B) is a static or linkonce-ODR function and is an inlining candidate
// elsewhere, and the current candidate callee (call it C) is large enough
@ -275,7 +248,6 @@ bool Inliner::shouldInline(CallSite CS) {
// FIXME: All of this logic should be sunk into getInlineCost. It relies on
// the internal implementation of the inline cost metrics rather than
// treating them as truly abstract units etc.
if (Caller->hasLocalLinkage() || Caller->hasLinkOnceODRLinkage()) {
int TotalSecondaryCost = 0;
// The candidate cost to be imposed upon the current function.
int CandidateCost = IC.getCost() - (InlineConstants::CallPenalty + 1);
@ -318,18 +290,54 @@ bool Inliner::shouldInline(CallSite CS) {
if (callerWillBeRemoved && !Caller->use_empty())
TotalSecondaryCost += InlineConstants::LastCallToStaticBonus;
if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost()) {
DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction() <<
" Cost = " << IC.getCost() <<
", outer Cost = " << TotalSecondaryCost << '\n');
emitAnalysis(
CS, Twine("Not inlining. Cost of inlining " +
if (inliningPreventsSomeOuterInline && TotalSecondaryCost < IC.getCost())
return true;
return false;
}
/// Return true if the inliner should attempt to inline at the given CallSite.
bool Inliner::shouldInline(CallSite CS) {
InlineCost IC = getInlineCost(CS);
if (IC.isAlways()) {
DEBUG(dbgs() << " Inlining: cost=always"
<< ", Call: " << *CS.getInstruction() << "\n");
emitAnalysis(CS, Twine(CS.getCalledFunction()->getName()) +
" should always be inlined (cost=always)");
return true;
}
if (IC.isNever()) {
DEBUG(dbgs() << " NOT Inlining: cost=never"
<< ", Call: " << *CS.getInstruction() << "\n");
emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
" should never be inlined (cost=never)"));
return false;
}
Function *Caller = CS.getCaller();
if (!IC) {
DEBUG(dbgs() << " NOT Inlining: cost=" << IC.getCost()
<< ", thres=" << (IC.getCostDelta() + IC.getCost())
<< ", Call: " << *CS.getInstruction() << "\n");
emitAnalysis(CS, Twine(CS.getCalledFunction()->getName() +
" too costly to inline (cost=") +
Twine(IC.getCost()) + ", threshold=" +
Twine(IC.getCostDelta() + IC.getCost()) + ")");
return false;
}
if (shouldBeDeferred(Caller, CS, IC)) {
DEBUG(dbgs() << " NOT Inlining: " << *CS.getInstruction()
<< " Cost = " << IC.getCost()
<< ", outer Cost = " << TotalSecondaryCost << '\n');
emitAnalysis(CS, Twine("Not inlining. Cost of inlining " +
CS.getCalledFunction()->getName() +
" increases the cost of inlining " +
CS.getCaller()->getName() + " in other contexts"));
return false;
}
}
DEBUG(dbgs() << " Inlining: cost=" << IC.getCost()
<< ", thres=" << (IC.getCostDelta() + IC.getCost())