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[SampleFDO] Treat names in profile as not cold only when profile symbol list 

is available

In rL372232, we treated names showing up in profile as not cold when
profile-sample-accurate is enabled. This caused 70k size regression in
Chrome/Android. The patch put a guard and only enable the change when
profile symbol list is available, i.e., keep the old behavior when profile
symbol list is not available.

Differential Revision: https://reviews.llvm.org/D67931

llvm-svn: 372665
This commit is contained in:
Wei Mi 2019-09-23 22:11:35 +00:00
parent 28b38c277a
commit 22fd88530b
2 changed files with 44 additions and 29 deletions
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45
llvm/lib/Transforms/IPO/SampleProfile.cpp
View File

@ -1770,27 +1770,32 @@ bool SampleProfileLoader::runOnFunction(Function &F, ModuleAnalysisManager *AM)
if (ProfSampleAccEnabled) {
// PSL -- profile symbol list include all the symbols in sampled binary.
// It is used to prevent new functions to be treated as cold.
// If ProfileSampleAccurate is true or F has profile-sample-accurate
// attribute, and if there is no profile symbol list read in, initialize
// all the function entry counts to 0; if there is profile symbol list, only
// initialize the entry count to 0 when current function is in the list.
if (!PSL || PSL->contains(F.getName()))
initialEntryCount = 0;
if (PSL) {
// Profile symbol list is available, initialize the entry count to 0
// only for functions in the list.
if (PSL->contains(F.getName()))
initialEntryCount = 0;
// When ProfileSampleAccurate is true, function without sample will be
// regarded as cold. To minimize the potential negative performance
// impact it could have, we want to be a little conservative here
// saying if a function shows up in the profile, no matter as outline
// function, inline instance or call targets, treat the function as not
// being cold. This will handle the cases such as most callsites of a
// function are inlined in sampled binary but not inlined in current
// build (because of source code drift, imprecise debug information, or
// the callsites are all cold individually but not cold accumulatively...),
// so the outline function showing up as cold in sampled binary will
// actually not be cold after current build.
StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
if (NamesInProfile.count(CanonName))
initialEntryCount = -1;
// When ProfileSampleAccurate is true, function without sample will be
// regarded as cold. To minimize the potential negative performance
// impact it could have, we want to be a little conservative here
// saying if a function shows up in the profile, no matter as outline
// function, inline instance or call targets, treat the function as not
// being cold. This will handle the cases such as most callsites of a
// function are inlined in sampled binary but not inlined in current
// build (because of source code drift, imprecise debug information, or
// the callsites are all cold individually but not cold
// accumulatively...), so the outline function showing up as cold in
// sampled binary will actually not be cold after current build.
StringRef CanonName = FunctionSamples::getCanonicalFnName(F);
if (NamesInProfile.count(CanonName))
initialEntryCount = -1;
} else {
// If there is no profile symbol list available, initialize all the
// function entry counts to 0. It means all the functions without
// profile will be regarded as cold.
initialEntryCount = 0;
}
}
F.setEntryCount(ProfileCount(initialEntryCount, Function::PCT_Real));

28
llvm/test/Transforms/SampleProfile/profile-sample-accurate.ll
View File

@ -1,11 +1,9 @@
; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/profsampleacc.extbinary.afdo -profile-summary-cutoff-hot=600000 -profile-sample-accurate -S | FileCheck %s
; RUN: opt < %s -passes=sample-profile -sample-profile-file=%S/Inputs/profsampleacc.extbinary.afdo -profile-summary-cutoff-hot=600000 -profile-sample-accurate -S | FileCheck %s
; With the hot cutoff being set to 600000, the inline instance of _Z3sumii
; in main is neither hot nor cold. Check it will still be inlined when
; profile-sample-accurate is enabled, and check _Z3sumii's function entry
; count won't be initialized to 0 because it shows up in the profile as
; inline instance.
; RUN: llvm-profdata merge -sample -extbinary -prof-sym-list=%S/Inputs/profile-symbol-list.text %S/Inputs/profsampleacc.extbinary.afdo -o %t.symlist.afdo
; RUN: opt < %s -sample-profile -sample-profile-file=%t.symlist.afdo -profile-summary-cutoff-hot=600000 -profile-sample-accurate -S | FileCheck %s --check-prefix=PROFSYMLIST
; RUN: opt < %s -passes=sample-profile -sample-profile-file=%t.symlist.afdo -profile-summary-cutoff-hot=600000 -profile-sample-accurate -S | FileCheck %s --check-prefix=PROFSYMLIST
;
; Original C++ test case
;
; #include <stdio.h>
@ -24,7 +22,13 @@
;
@.str = private unnamed_addr constant [11 x i8] c"sum is %d\0A\00", align 1
; CHECK: define i32 @_Z3sumii{{.*}}!prof ![[UNKNOWN_ID:[0-9]+]]
; Check _Z3sumii's function entry count will be intialized to 0 if no profile
; symbol list is available.
; If symbol list is available, _Z3sumii's function entry count will be
; initialized to -1 if it shows up in the profile.
;
; CHECK: define i32 @_Z3sumii{{.*}}!prof ![[ZERO_ID:[0-9]+]]
; PROFSYMLIST: define i32 @_Z3sumii{{.*}}!prof ![[UNKNOWN_ID:[0-9]+]]
; Function Attrs: nounwind uwtable
define i32 @_Z3sumii(i32 %x, i32 %y) !dbg !4 {
entry:
@ -60,10 +64,15 @@ while.body: ; preds = %while.cond
%cmp1 = icmp ne i32 %1, 100, !dbg !16
br i1 %cmp1, label %if.then, label %if.else, !dbg !16
; Check _Z3sumii is inlined at this callsite.
; With the hot cutoff being set to 600000, the inline instance of _Z3sumii
; in main is neither hot nor cold. Check it will still be inlined when
; profile-sample-accurate is enabled.
; CHECK: if.then:
; CHECK-NOT: call i32 @_Z3sumii
; CHECK: if.else:
; PROFSYMLIST: if.then:
; PROFSYMLIST-NOT: call i32 @_Z3sumii
; PROFSYMLIST: if.else:
if.then: ; preds = %while.body
%2 = load i32, i32* %i, align 4, !dbg !18
%3 = load i32, i32* %s, align 4, !dbg !18
@ -90,7 +99,8 @@ declare i32 @printf(i8*, ...) #2
!llvm.module.flags = !{!8, !9}
!llvm.ident = !{!10}
; CHECK: ![[UNKNOWN_ID]] = !{!"function_entry_count", i64 -1}
; CHECK: ![[ZERO_ID]] = !{!"function_entry_count", i64 0}
; PROFSYMLIST: ![[UNKNOWN_ID]] = !{!"function_entry_count", i64 -1}
!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.5 ", isOptimized: false, emissionKind: NoDebug, file: !1, enums: !2, retainedTypes: !2, globals: !2, imports: !2)
!1 = !DIFile(filename: "calls.cc", directory: ".")
!2 = !{}