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[HotColdSplit] With PGO add profile entry metadata to split cold function

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Summary:
When compiling with profile data, ensure the split cold function gets
cold function_entry_count metadata (just use 0 since it should be cold).
Otherwise with function sections it will not be placed in the unlikely
text section with other cold code.

Reviewers: vsk

Subscribers: sebpop, hiraditya, davidxl, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57900

llvm-svn: 353434
This commit is contained in:
Teresa Johnson 2019-02-07 17:50:35 +00:00
parent b2414895c7
commit a1faa7ab09
2 changed files with 54 additions and 2 deletions
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13
lib/Transforms/IPO/HotColdSplitting.cpp
View File

@ -144,8 +144,10 @@ static bool mayExtractBlock(const BasicBlock &BB) {
}
/// Mark \p F cold. Based on this assumption, also optimize it for minimum size.
/// If \p UpdateEntryCount is true (set when this is a new split function and
/// module has profile data), set entry count to 0 to ensure treated as cold.
/// Return true if the function is changed.
static bool markFunctionCold(Function &F) {
static bool markFunctionCold(Function &F, bool UpdateEntryCount = false) {
assert(!F.hasFnAttribute(Attribute::OptimizeNone) && "Can't mark this cold");
bool Changed = false;
if (!F.hasFnAttribute(Attribute::Cold)) {
@ -156,6 +158,13 @@ static bool markFunctionCold(Function &F) {
F.addFnAttr(Attribute::MinSize);
Changed = true;
}
if (UpdateEntryCount) {
// Set the entry count to 0 to ensure it is placed in the unlikely text
// section when function sections are enabled.
F.setEntryCount(0);
Changed = true;
}
return Changed;
}
@ -340,7 +349,7 @@ Function *HotColdSplitting::extractColdRegion(const BlockSequence &Region,
}
CI->setIsNoInline();
markFunctionCold(*OutF);
markFunctionCold(*OutF, BFI != nullptr);
LLVM_DEBUG(llvm::dbgs() << "Outlined Region: " << *OutF);
ORE.emit([&]() {

43
test/Transforms/HotColdSplit/coldentrycount.ll Normal file
View File

@ -0,0 +1,43 @@
; Test to ensure that split cold function gets 0 entry count profile
; metadata when compiling with pgo.
; RUN: opt -hotcoldsplit -hotcoldsplit-threshold=0 -S < %s | FileCheck %s
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.14.0"
; CHECK-LABEL: @fun
; CHECK: call void @fun.cold.1
define void @fun() !prof !14 {
entry:
br i1 undef, label %if.then, label %if.else
if.then:
ret void
if.else:
call void @sink()
ret void
}
declare void @sink() cold
; CHECK: define {{.*}} @fun.cold.1{{.*}} ![[PROF:[0-9]+]]
; CHECK: ![[PROF]] = !{!"function_entry_count", i64 0}
!llvm.module.flags = !{!0}
!0 = !{i32 1, !"ProfileSummary", !1}
!1 = !{!2, !3, !4, !5, !6, !7, !8, !9}
!2 = !{!"ProfileFormat", !"InstrProf"}
!3 = !{!"TotalCount", i64 10000}
!4 = !{!"MaxCount", i64 10}
!5 = !{!"MaxInternalCount", i64 1}
!6 = !{!"MaxFunctionCount", i64 1000}
!7 = !{!"NumCounts", i64 3}
!8 = !{!"NumFunctions", i64 3}
!9 = !{!"DetailedSummary", !10}
!10 = !{!11, !12, !13}
!11 = !{i32 10000, i64 100, i32 1}
!12 = !{i32 999000, i64 100, i32 1}
!13 = !{i32 999999, i64 1, i32 2}
!14 = !{!"function_entry_count", i64 100}