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[Inliner] Do not mix callsite and callee hotness based updates.

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Update threshold based on callee's hotness only when BFI is not available.
Otherwise use only callsite's hotness. This makes it easier to reason about
hotness related threshold updates.

Differential revision: https://reviews.llvm.org/D33157

llvm-svn: 303210
This commit is contained in:
Easwaran Raman 2017-05-16 21:18:09 +00:00
parent 82dcf06a2b
commit d91313ddb5
2 changed files with 32 additions and 20 deletions
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42
lib/Analysis/InlineCost.cpp
View File

@ -669,21 +669,33 @@ void CallAnalyzer::updateThreshold(CallSite CS, Function &Callee) {
Threshold = MaxIfValid(Threshold, Params.HintThreshold);
if (PSI) {
BlockFrequencyInfo *CallerBFI = GetBFI ? &((*GetBFI)(*Caller)) : nullptr;
if (PSI->isHotCallSite(CS, CallerBFI)) {
DEBUG(dbgs() << "Hot callsite.\n");
Threshold = Params.HotCallSiteThreshold.getValue();
} else if (PSI->isFunctionEntryHot(&Callee)) {
DEBUG(dbgs() << "Hot callee.\n");
// If callsite hotness can not be determined, we may still know
// that the callee is hot and treat it as a weaker hint for threshold
// increase.
Threshold = MaxIfValid(Threshold, Params.HintThreshold);
} else if (PSI->isColdCallSite(CS, CallerBFI)) {
DEBUG(dbgs() << "Cold callsite.\n");
Threshold = MinIfValid(Threshold, Params.ColdCallSiteThreshold);
} else if (PSI->isFunctionEntryCold(&Callee)) {
DEBUG(dbgs() << "Cold callee.\n");
Threshold = MinIfValid(Threshold, Params.ColdThreshold);
// FIXME: After switching to the new passmanager, simplify the logic below
// by checking only the callsite hotness/coldness. The check for CallerBFI
// exists only because we do not have BFI available with the old PM.
//
// Use callee's hotness information only if we have no way of determining
// callsite's hotness information. Callsite hotness can be determined if
// sample profile is used (which adds hotness metadata to calls) or if
// caller's BlockFrequencyInfo is available.
if (CallerBFI || PSI->hasSampleProfile()) {
if (PSI->isHotCallSite(CS, CallerBFI)) {
DEBUG(dbgs() << "Hot callsite.\n");
Threshold = Params.HotCallSiteThreshold.getValue();
} else if (PSI->isColdCallSite(CS, CallerBFI)) {
DEBUG(dbgs() << "Cold callsite.\n");
Threshold = MinIfValid(Threshold, Params.ColdCallSiteThreshold);
}
} else {
if (PSI->isFunctionEntryHot(&Callee)) {
DEBUG(dbgs() << "Hot callee.\n");
// If callsite hotness can not be determined, we may still know
// that the callee is hot and treat it as a weaker hint for threshold
// increase.
Threshold = MaxIfValid(Threshold, Params.HintThreshold);
} else if (PSI->isFunctionEntryCold(&Callee)) {
DEBUG(dbgs() << "Cold callee.\n");
Threshold = MinIfValid(Threshold, Params.ColdThreshold);
}
}
}
}

10
test/Transforms/Inline/inline-hot-callee.ll
View File

@ -1,10 +1,10 @@
; RUN: opt < %s -inline -inline-threshold=0 -inlinehint-threshold=100 -S | FileCheck %s
; RUN: opt < %s -passes='require<profile-summary>,cgscc(inline)' -inline-threshold=0 -inlinehint-threshold=100 -S | FileCheck %s
; This tests that a hot callee gets the (higher) inlinehint-threshold even without
; inline hints and gets inlined because the cost is less than inlinehint-threshold.
; A cold callee with identical body does not get inlined because cost exceeds the
; inline-threshold
; This tests that a hot callee gets the (higher) inlinehint-threshold even
; without inline hints and gets inlined because the cost is less than
; inlinehint-threshold. A cold callee with identical body does not get inlined
; because cost exceeds the inline-threshold. This test is relevant only when the
; old pass manager is used.
define i32 @callee1(i32 %x) !prof !21 {
%x1 = add i32 %x, 1