[llvm] 408bb9a - Add a regression test to guard the 0 hot-caller threshold in SamplePGO + ThinLTO. - Add a comment near where the threshold is set.
Mingming Liu via llvm-commits
llvm-commits at lists.llvm.org
Mon Apr 25 11:30:52 PDT 2022
Author: Mingming Liu
Date: 2022-04-25T18:29:56Z
New Revision: 408bb9a375ac9f69816823f99cf0a64c1ee8a931
URL: https://github.com/llvm/llvm-project/commit/408bb9a375ac9f69816823f99cf0a64c1ee8a931
DIFF: https://github.com/llvm/llvm-project/commit/408bb9a375ac9f69816823f99cf0a64c1ee8a931.diff
LOG: Add a regression test to guard the 0 hot-caller threshold in SamplePGO + ThinLTO. - Add a comment near where the threshold is set.
Added:
llvm/test/Other/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof
llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll
Modified:
llvm/lib/Passes/PassBuilderPipelines.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index ca48a5bd09cb9..dcc0756f7f528 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -713,6 +713,12 @@ ModuleInlinerWrapperPass
PassBuilder::buildInlinerPipeline(OptimizationLevel Level,
ThinOrFullLTOPhase Phase) {
InlineParams IP = getInlineParamsFromOptLevel(Level);
+ // For PreLinkThinLTO + SamplePGO, set hot-caller threshold to 0 to
+ // disable hot callsite inline (as much as possible [1]) because it makes
+ // profile annotation in the backend inaccurate.
+ //
+ // [1] Note the cost of a function could be below zero due to erased
+ // prologue / epilogue.
if (Phase == ThinOrFullLTOPhase::ThinLTOPreLink && PGOOpt &&
PGOOpt->Action == PGOOptions::SampleUse)
IP.HotCallSiteThreshold = 0;
@@ -786,6 +792,12 @@ PassBuilder::buildModuleInlinerPipeline(OptimizationLevel Level,
ModulePassManager MPM;
InlineParams IP = getInlineParamsFromOptLevel(Level);
+ // For PreLinkThinLTO + SamplePGO, set hot-caller threshold to 0 to
+ // disable hot callsite inline (as much as possible [1]) because it makes
+ // profile annotation in the backend inaccurate.
+ //
+ // [1] Note the cost of a function could be below zero due to erased
+ // prologue / epilogue.
if (Phase == ThinOrFullLTOPhase::ThinLTOPreLink && PGOOpt &&
PGOOpt->Action == PGOOptions::SampleUse)
IP.HotCallSiteThreshold = 0;
diff --git a/llvm/test/Other/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof b/llvm/test/Other/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof
new file mode 100644
index 0000000000000..fa55d7df6bef9
--- /dev/null
+++ b/llvm/test/Other/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof
@@ -0,0 +1,16 @@
+_Z3sumii:105580:5279
+ 0: 5279
+ 1: 5279
+ 2: 5279
+_Z4sum1ii:105580:5279
+ 0: 5279
+ 1: 5279
+ 2: 5279
+main:225715:0
+ 2.1: 5553
+ 3: 4522
+ # This indicates that at line 3 of this function, the 'then' branch
+ # of the conditional is taken (discriminator '1').
+ 3.1: 5752 _Z3sumii:5860
+ 4: 20 _Z4sum1ii:20
+ 4.1: 11504 _Z4sum1ii:11720
diff --git a/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll b/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll
new file mode 100644
index 0000000000000..f9d608a718415
--- /dev/null
+++ b/llvm/test/Other/new-pm-thinlto-prelink-samplepgo-inline-threshold.ll
@@ -0,0 +1,122 @@
+; Tests that hot callsite threshold is set to 0 artifically for thinlto-prelink pipeline.
+;
+; Function `sum` is annotated with inline cost -1 and function `sum1` is
+; annotated with inline cost 0, by function attribute `function-inline-cost`.
+;
+; `if.then` basic block is hot so the callsite threshold is set to 0.
+; `while.body.split` basic block is cold so threshold is calculated using
+; the rest of default heuristics, which should be sufficient to inline a
+; function with 0 cost.
+
+; RUN: opt < %s -pass-remarks=inline -pass-remarks-missed=inline -passes='thinlto-pre-link<O2>' -pgo-kind=pgo-sample-use-pipeline -sample-profile-file=%S/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof -S | FileCheck %s
+
+; RUN: opt < %s -pass-remarks=inline -pass-remarks-missed=inline -passes='thinlto-pre-link<O2>' -pgo-kind=pgo-sample-use-pipeline -sample-profile-file=%S/Inputs/new-pm-thinlto-prelink-samplepgo-inline-threshold.prof -S 2>&1 | FileCheck %s -check-prefix=REMARK
+
+; Original C++ test case
+;
+; #include <stdio.h>
+
+; int sum(int x, int y) { return x + y; }
+
+; int sum1(int x, int y) { return x + y; }
+
+; int main() {
+; int s, i = 0;
+; while (i++ < 20000 * 20000) {
+; if (i != 100) s = sum(i, s);
+; s = sum1(i, s);
+; }
+; printf("sum is %d\n", s);
+; return 0;
+; }
+;
+
+; REMARK: test.cc:14:9: '_Z4sum1ii' inlined into 'main' with (cost=0, threshold=45) at callsite main:4:9;
+; REMARK: test.cc:13:23: '_Z3sumii' inlined into 'main' with (cost=-1, threshold=0) at callsite main:3:23.2;
+; REMARK: test.cc:14:9: '_Z4sum1ii' not inlined into 'main' because too costly to inline (cost=0, threshold=0)
+
+; ModuleID = 'test.cc'
+source_filename = "test.cc"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+ at .str = constant [11 x i8] c"sum is %d\0A\00", align 1
+
+define i32 @_Z3sumii(i32 %x, i32 %y) "function-inline-cost"="-1" #0 !dbg !7 {
+entry:
+ %add = add nsw i32 %y, %x, !dbg !10
+ ret i32 %add, !dbg !11
+}
+
+define i32 @_Z4sum1ii(i32 %x, i32 %y) "function-inline-cost"="0" #0 !dbg !12 {
+entry:
+ %add = add nsw i32 %y, %x, !dbg !13
+ ret i32 %add, !dbg !14
+}
+
+define i32 @main() #0 !dbg !15 {
+entry:
+ br label %while.body, !dbg !16
+
+while.body: ; preds = %entry, %if.end
+ %inc14 = phi i32 [ 1, %entry ], [ %inc, %if.end ]
+ %s.013 = phi i32 [ undef, %entry ], [ %phi.call, %if.end ]
+ %cmp1.not = icmp eq i32 %inc14, 100, !dbg !17
+ br i1 %cmp1.not, label %while.body.split, label %if.then, !dbg !18
+
+while.body.split: ; preds = %while.body
+; CHECK-NOT: call noundef i32 @_Z4sum1ii
+ %call211 = call noundef i32 @_Z4sum1ii(i32 100, i32 %s.013), !dbg !19
+ br label %if.end, !dbg !18
+
+if.then: ; preds = %while.body
+; CHECK-NOT: call i32 @_Z3sumii
+; CHECK: call i32 @_Z4sum1ii
+ %call = call i32 @_Z3sumii(i32 %inc14, i32 %s.013), !dbg !20
+ %call212 = call i32 @_Z4sum1ii(i32 %inc14, i32 %call), !dbg !19
+ br label %if.end, !dbg !21
+
+if.end: ; preds = %while.body.split, %if.then
+ %phi.call = phi i32 [ %call211, %while.body.split ], [ %call212, %if.then ], !dbg !19
+ %inc = add i32 %inc14, 1, !dbg !22
+ %exitcond.not = icmp eq i32 %inc, 400000001, !dbg !23
+ br i1 %exitcond.not, label %while.end, label %while.body, !dbg !16, !llvm.loop !24
+
+while.end: ; preds = %if.end
+ %call3 = tail call i32 (i8*, ...) @printf(i8* dereferenceable(1) getelementptr inbounds ([11 x i8], [11 x i8]* @.str, i64 0, i64 0), i32 %phi.call), !dbg !27
+ ret i32 0, !dbg !28
+}
+
+declare i32 @printf(i8* nocapture noundef readonly, ...)
+
+attributes #0 = {"use-sample-profile"}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2, !3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !1, producer: "clang version 14.0.0 (https://github.com/llvm/llvm-project.git 329fda39c507e8740978d10458451dcdb21563be)", isOptimized: true, runtimeVersion: 0, emissionKind: LineTablesOnly, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "test.cc", directory: "", checksumkind: CSK_MD5, checksum: "e8c44edbdcc2c41f9f891ac2b2ddd591")
+!2 = !{i32 7, !"Dwarf Version", i32 5}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!7 = distinct !DISubprogram(name: "sum", scope: !1, file: !1, line: 6, type: !8, scopeLine: 6, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !9)
+!8 = !DISubroutineType(types: !9)
+!9 = !{}
+!10 = !DILocation(line: 6, column: 60, scope: !7)
+!11 = !DILocation(line: 6, column: 51, scope: !7)
+!12 = distinct !DISubprogram(name: "sum1", scope: !1, file: !1, line: 8, type: !8, scopeLine: 8, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !9)
+!13 = !DILocation(line: 8, column: 61, scope: !12)
+!14 = !DILocation(line: 8, column: 52, scope: !12)
+!15 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 10, type: !8, scopeLine: 10, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !9)
+!16 = !DILocation(line: 12, column: 3, scope: !15)
+!17 = !DILocation(line: 13, column: 11, scope: !15)
+!18 = !DILocation(line: 13, column: 9, scope: !15)
+!19 = !DILocation(line: 14, column: 9, scope: !15)
+!20 = !DILocation(line: 13, column: 23, scope: !15)
+!21 = !DILocation(line: 13, column: 19, scope: !15)
+!22 = !DILocation(line: 12, column: 11, scope: !15)
+!23 = !DILocation(line: 12, column: 14, scope: !15)
+!24 = distinct !{!24, !16, !25, !26}
+!25 = !DILocation(line: 15, column: 3, scope: !15)
+!26 = !{!"llvm.loop.mustprogress"}
+!27 = !DILocation(line: 16, column: 3, scope: !15)
+!28 = !DILocation(line: 17, column: 3, scope: !15)
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