[CSSPGO] Return error_code for missing probe profile #102085
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@llvm/pr-subscribers-pgo @llvm/pr-subscribers-llvm-transforms Author: Lei Wang (wlei-llvm) ChangesWe should undo this https://reviews.llvm.org/D102007 after undoing https://reviews.llvm.org/D104477 to use missing probe to represent unknown count, zero count and unknown count are different to profile inference. It only affects post-inline(linker) pipeline(with Patch is 20.01 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/102085.diff 3 Files Affected:
diff --git a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
index 32bf7b8c96be3d..114159ab524bfe 100644
--- a/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
+++ b/llvm/include/llvm/Transforms/Utils/SampleProfileLoaderBaseImpl.h
@@ -449,9 +449,6 @@ SampleProfileLoaderBaseImpl<BT>::getInstWeightImpl(const InstructionT &Inst) {
return R;
}
-// Here use error_code to represent: 1) The dangling probe. 2) Ignore the weight
-// of non-probe instruction. So if all instructions of the BB give error_code,
-// tell the inference algorithm to infer the BB weight.
template <typename BT>
ErrorOr<uint64_t>
SampleProfileLoaderBaseImpl<BT>::getProbeWeight(const InstructionT &Inst) {
@@ -464,17 +461,8 @@ SampleProfileLoaderBaseImpl<BT>::getProbeWeight(const InstructionT &Inst) {
return std::error_code();
const FunctionSamples *FS = findFunctionSamples(Inst);
- // If none of the instruction has FunctionSample, we choose to return zero
- // value sample to indicate the BB is cold. This could happen when the
- // instruction is from inlinee and no profile data is found.
- // FIXME: This should not be affected by the source drift issue as 1) if the
- // newly added function is top-level inliner, it won't match the CFG checksum
- // in the function profile or 2) if it's the inlinee, the inlinee should have
- // a profile, otherwise it wouldn't be inlined. For non-probe based profile,
- // we can improve it by adding a switch for profile-sample-block-accurate for
- // block level counts in the future.
if (!FS)
- return 0;
+ return std::error_code();
auto R = FS->findSamplesAt(Probe->Id, Probe->Discriminator);
if (R) {
diff --git a/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-missing-probe.prof b/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-missing-probe.prof
new file mode 100644
index 00000000000000..cc50d6a2fad2b9
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/Inputs/pseudo-probe-missing-probe.prof
@@ -0,0 +1,13 @@
+main:89650:0
+ 1: 0
+ 2: 16724
+ 3: 16724
+ 4: 14342
+ 5: 15026 bar:15026
+ 6: 1882
+ 8: 16724
+ 9: 0
+ !CFGChecksum: 563091374530180
+bar:15026:15026
+ 1: 15026
+ !CFGChecksum: 4294967295
diff --git a/llvm/test/Transforms/SampleProfile/pseudo-probe-missing-probe.ll b/llvm/test/Transforms/SampleProfile/pseudo-probe-missing-probe.ll
new file mode 100644
index 00000000000000..23d322c5cc99f5
--- /dev/null
+++ b/llvm/test/Transforms/SampleProfile/pseudo-probe-missing-probe.ll
@@ -0,0 +1,327 @@
+; RUN: opt < %s -passes=sample-profile --overwrite-existing-weights -sample-profile-file=%S/Inputs/pseudo-probe-missing-probe.prof | opt -passes='print<branch-prob>' -disable-output 2>&1 | FileCheck %s
+
+; CHECK: edge %while.body -> %if.then probability is 0x7212005e / 0x80000000 = 89.12% [HOT edge]
+; CHECK: edge %while.body -> %if.else probability is 0x0dedffa2 / 0x80000000 = 10.88%
+
+; CHECK-NOT: edge %while.body -> %if.then probability is 0x80000000 / 0x80000000 = 100.00% [HOT edge]
+; CHECK-NOT: edge %while.body -> %if.else probability is 0x00000000 / 0x80000000 = 0.00%
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@x = dso_local global i32 0, align 4, !dbg !0
+
+; Function Attrs: noinline nounwind uwtable
+define dso_local void @bar(i32 noundef %i) #0 !dbg !47 !prof !52 {
+entry:
+ #dbg_value(i32 %i, !51, !DIExpression(), !53)
+ call void @llvm.pseudoprobe(i64 -2012135647395072713, i64 1, i32 0, i64 -1), !dbg !54
+ %0 = load volatile i32, ptr @x, align 4, !dbg !54, !tbaa !55
+ %add = add nsw i32 %0, 5, !dbg !54
+ store volatile i32 %add, ptr @x, align 4, !dbg !54, !tbaa !55
+ ret void, !dbg !59
+}
+
+; Function Attrs: nounwind uwtable
+define dso_local void @baz(i32 noundef %i) #1 !dbg !60 !prof !63 {
+entry:
+ #dbg_value(i32 %i, !62, !DIExpression(), !64)
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 1, i32 0, i64 -1), !dbg !65
+ %rem = srem i32 %i, 100, !dbg !67
+ %tobool = icmp ne i32 %rem, 0, !dbg !67
+ br i1 %tobool, label %if.then, label %if.end, !dbg !68
+
+if.then: ; preds = %entry
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 2, i32 0, i64 -1), !dbg !69
+ %0 = load volatile i32, ptr @x, align 4, !dbg !69, !tbaa !55
+ %inc = add nsw i32 %0, 1, !dbg !69
+ store volatile i32 %inc, ptr @x, align 4, !dbg !69, !tbaa !55
+ br label %if.end, !dbg !70
+
+if.end: ; preds = %if.then, %entry
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 3, i32 0, i64 -1), !dbg !71
+ %1 = load volatile i32, ptr @x, align 4, !dbg !71, !tbaa !55
+ %add = add nsw i32 %1, 2, !dbg !71
+ store volatile i32 %add, ptr @x, align 4, !dbg !71, !tbaa !55
+ %rem1 = srem i32 %i, 2, !dbg !72
+ %tobool2 = icmp ne i32 %rem1, 0, !dbg !72
+ br i1 %tobool2, label %if.then3, label %if.else, !dbg !74
+
+if.then3: ; preds = %if.end
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 4, i32 0, i64 -1), !dbg !75
+ %2 = load volatile i32, ptr @x, align 4, !dbg !75, !tbaa !55
+ %inc4 = add nsw i32 %2, 1, !dbg !75
+ store volatile i32 %inc4, ptr @x, align 4, !dbg !75, !tbaa !55
+ br label %if.end11, !dbg !76
+
+if.else: ; preds = %if.end
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 5, i32 0, i64 -1), !dbg !77
+ %rem5 = srem i32 %i, 3, !dbg !79
+ %tobool6 = icmp ne i32 %rem5, 0, !dbg !79
+ br i1 %tobool6, label %if.then7, label %if.else9, !dbg !80
+
+if.then7: ; preds = %if.else
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 6, i32 0, i64 -1), !dbg !81
+ %3 = load volatile i32, ptr @x, align 4, !dbg !81, !tbaa !55
+ %add8 = add nsw i32 %3, 2, !dbg !81
+ store volatile i32 %add8, ptr @x, align 4, !dbg !81, !tbaa !55
+ br label %if.end11, !dbg !82
+
+if.else9: ; preds = %if.else
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 7, i32 0, i64 -1), !dbg !83
+ %4 = load volatile i32, ptr @x, align 4, !dbg !83, !tbaa !55
+ %dec = add nsw i32 %4, -1, !dbg !83
+ store volatile i32 %dec, ptr @x, align 4, !dbg !83, !tbaa !55
+ br label %if.end11
+
+if.end11: ; preds = %if.then7, %if.else9, %if.then3
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 9, i32 0, i64 -1), !dbg !84
+ ret void, !dbg !84
+}
+
+; Function Attrs: nounwind uwtable
+define dso_local i32 @main() #1 !dbg !85 !prof !90 {
+entry:
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 1, i32 0, i64 -1), !dbg !91
+ #dbg_value(i32 0, !89, !DIExpression(), !92)
+ br label %while.cond, !dbg !93
+
+while.cond: ; preds = %if.end, %entry
+ %i.0 = phi i32 [ 0, %entry ], [ %inc, %if.end ], !dbg !92
+ #dbg_value(i32 %i.0, !89, !DIExpression(), !92)
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 2, i32 0, i64 -1), !dbg !94
+ %inc = add nsw i32 %i.0, 1, !dbg !94
+ #dbg_value(i32 %inc, !89, !DIExpression(), !92)
+ %cmp = icmp slt i32 %i.0, 160000000, !dbg !95
+ br i1 %cmp, label %while.body, label %while.end, !dbg !93, !prof !96
+
+while.body: ; preds = %while.cond
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 3, i32 0, i64 -1), !dbg !97
+ %rem = srem i32 %inc, 10, !dbg !100
+ %tobool = icmp ne i32 %rem, 0, !dbg !100
+ br i1 %tobool, label %if.then, label %if.else, !dbg !101, !prof !102
+
+if.then: ; preds = %while.body
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 4, i32 0, i64 -1), !dbg !103
+ call void @bar(i32 noundef %inc), !dbg !104, !prof !106
+ br label %if.end, !dbg !107
+
+if.else: ; preds = %while.body
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 6, i32 0, i64 -1), !dbg !108
+ #dbg_value(i32 %inc, !62, !DIExpression(), !109)
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 1, i32 0, i64 -1), !dbg !112
+ %rem.i = srem i32 %inc, 100, !dbg !113
+ %tobool.i = icmp ne i32 %rem.i, 0, !dbg !113
+ br i1 %tobool.i, label %if.then.i, label %if.end.i, !dbg !114, !prof !115
+
+if.then.i: ; preds = %if.else
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 2, i32 0, i64 -1), !dbg !116
+ %0 = load volatile i32, ptr @x, align 4, !dbg !116, !tbaa !55
+ %inc.i = add nsw i32 %0, 1, !dbg !116
+ store volatile i32 %inc.i, ptr @x, align 4, !dbg !116, !tbaa !55
+ br label %if.end.i, !dbg !117
+
+if.end.i: ; preds = %if.then.i, %if.else
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 3, i32 0, i64 -1), !dbg !118
+ %1 = load volatile i32, ptr @x, align 4, !dbg !118, !tbaa !55
+ %add.i = add nsw i32 %1, 2, !dbg !118
+ store volatile i32 %add.i, ptr @x, align 4, !dbg !118, !tbaa !55
+ %rem1.i = srem i32 %inc, 2, !dbg !119
+ %tobool2.i = icmp ne i32 %rem1.i, 0, !dbg !119
+ br i1 %tobool2.i, label %if.then3.i, label %if.else.i, !dbg !120, !prof !121
+
+if.then3.i: ; preds = %if.end.i
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 4, i32 0, i64 -1), !dbg !122
+ %2 = load volatile i32, ptr @x, align 4, !dbg !122, !tbaa !55
+ %inc4.i = add nsw i32 %2, 1, !dbg !122
+ store volatile i32 %inc4.i, ptr @x, align 4, !dbg !122, !tbaa !55
+ br label %baz.exit, !dbg !123
+
+if.else.i: ; preds = %if.end.i
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 5, i32 0, i64 -1), !dbg !124
+ %rem5.i = srem i32 %inc, 3, !dbg !125
+ %tobool6.i = icmp ne i32 %rem5.i, 0, !dbg !125
+ br i1 %tobool6.i, label %if.then7.i, label %if.else9.i, !dbg !126, !prof !127
+
+if.then7.i: ; preds = %if.else.i
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 6, i32 0, i64 -1), !dbg !128
+ %3 = load volatile i32, ptr @x, align 4, !dbg !128, !tbaa !55
+ %add8.i = add nsw i32 %3, 2, !dbg !128
+ store volatile i32 %add8.i, ptr @x, align 4, !dbg !128, !tbaa !55
+ br label %baz.exit, !dbg !129
+
+if.else9.i: ; preds = %if.else.i
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 7, i32 0, i64 -1), !dbg !130
+ %4 = load volatile i32, ptr @x, align 4, !dbg !130, !tbaa !55
+ %dec.i = add nsw i32 %4, -1, !dbg !130
+ store volatile i32 %dec.i, ptr @x, align 4, !dbg !130, !tbaa !55
+ br label %baz.exit
+
+baz.exit: ; preds = %if.then3.i, %if.then7.i, %if.else9.i
+ call void @llvm.pseudoprobe(i64 7546896869197086323, i64 9, i32 0, i64 -1), !dbg !131
+ br label %if.end
+
+if.end: ; preds = %baz.exit, %if.then
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 8, i32 0, i64 -1), !dbg !93
+ br label %while.cond, !dbg !93, !llvm.loop !132
+
+while.end: ; preds = %while.cond
+ call void @llvm.pseudoprobe(i64 -2624081020897602054, i64 9, i32 0, i64 -1), !dbg !135
+ ret i32 0, !dbg !135
+}
+
+; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+declare void @llvm.lifetime.start.p0(i64 immarg, ptr nocapture) #2
+
+; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite)
+declare void @llvm.lifetime.end.p0(i64 immarg, ptr nocapture) #2
+
+; Function Attrs: mustprogress nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: readwrite)
+declare void @llvm.pseudoprobe(i64, i64, i32, i64) #3
+
+attributes #0 = { noinline nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "use-sample-profile" }
+attributes #1 = { nounwind uwtable "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cmov,+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" "use-sample-profile" }
+attributes #2 = { mustprogress nocallback nofree nosync nounwind willreturn memory(argmem: readwrite) }
+attributes #3 = { mustprogress nocallback nofree nosync nounwind willreturn memory(inaccessiblemem: readwrite) }
+
+!llvm.dbg.cu = !{!2}
+!llvm.module.flags = !{!7, !8, !9, !10, !11, !12, !13, !14}
+!llvm.ident = !{!43}
+!llvm.pseudo_probe_desc = !{!44, !45, !46}
+
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "x", scope: !2, file: !3, line: 1, type: !5, isLocal: false, isDefinition: true)
+!2 = distinct !DICompileUnit(language: DW_LANG_C11, file: !3, producer: "clang version 20.0.0", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, globals: !4, splitDebugInlining: false, nameTableKind: None)
+!3 = !DIFile(filename: "test.c", directory: "/home/", checksumkind: CSK_MD5, checksum: "b67c15e928f76c51702a59639dbebb4c")
+!4 = !{!0}
+!5 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !6)
+!6 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!7 = !{i32 7, !"Dwarf Version", i32 5}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = !{i32 8, !"PIC Level", i32 2}
+!11 = !{i32 7, !"PIE Level", i32 2}
+!12 = !{i32 7, !"uwtable", i32 2}
+!13 = !{i32 7, !"debug-info-assignment-tracking", i1 true}
+!14 = !{i32 1, !"ProfileSummary", !15}
+!15 = !{!16, !17, !18, !19, !20, !21, !22, !23, !24, !25}
+!16 = !{!"ProfileFormat", !"SampleProfile"}
+!17 = !{!"TotalCount", i64 105360}
+!18 = !{!"MaxCount", i64 16724}
+!19 = !{!"MaxInternalCount", i64 0}
+!20 = !{!"MaxFunctionCount", i64 15026}
+!21 = !{!"NumCounts", i64 14}
+!22 = !{!"NumFunctions", i64 2}
+!23 = !{!"IsPartialProfile", i64 0}
+!24 = !{!"PartialProfileRatio", double 0.000000e+00}
+!25 = !{!"DetailedSummary", !26}
+!26 = !{!27, !28, !29, !30, !31, !32, !33, !34, !35, !36, !37, !38, !39, !40, !41, !42}
+!27 = !{i32 10000, i64 16724, i32 3}
+!28 = !{i32 100000, i64 16724, i32 3}
+!29 = !{i32 200000, i64 16724, i32 3}
+!30 = !{i32 300000, i64 16724, i32 3}
+!31 = !{i32 400000, i64 16724, i32 3}
+!32 = !{i32 500000, i64 15026, i32 5}
+!33 = !{i32 600000, i64 15026, i32 5}
+!34 = !{i32 700000, i64 15026, i32 5}
+!35 = !{i32 800000, i64 14342, i32 6}
+!36 = !{i32 900000, i64 1882, i32 8}
+!37 = !{i32 950000, i64 1872, i32 10}
+!38 = !{i32 990000, i64 1550, i32 12}
+!39 = !{i32 999000, i64 1550, i32 12}
+!40 = !{i32 999900, i64 1550, i32 12}
+!41 = !{i32 999990, i64 1550, i32 12}
+!42 = !{i32 999999, i64 1550, i32 12}
+!43 = !{!"clang version 20.0.0"}
+!44 = !{i64 -2012135647395072713, i64 4294967295, !"bar"}
+!45 = !{i64 7546896869197086323, i64 191430930410, !"baz"}
+!46 = !{i64 -2624081020897602054, i64 563091374530180, !"main"}
+!47 = distinct !DISubprogram(name: "bar", scope: !3, file: !3, line: 3, type: !48, scopeLine: 3, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !50)
+!48 = !DISubroutineType(types: !49)
+!49 = !{null, !6}
+!50 = !{!51}
+!51 = !DILocalVariable(name: "i", arg: 1, scope: !47, file: !3, line: 3, type: !6)
+!52 = !{!"function_entry_count", i64 15026}
+!53 = !DILocation(line: 0, scope: !47)
+!54 = !DILocation(line: 4, column: 5, scope: !47)
+!55 = !{!56, !56, i64 0}
+!56 = !{!"int", !57, i64 0}
+!57 = !{!"omnipotent char", !58, i64 0}
+!58 = !{!"Simple C/C++ TBAA"}
+!59 = !DILocation(line: 8, column: 1, scope: !47)
+!60 = distinct !DISubprogram(name: "baz", scope: !3, file: !3, line: 10, type: !48, scopeLine: 10, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !61)
+!61 = !{!62}
+!62 = !DILocalVariable(name: "i", arg: 1, scope: !60, file: !3, line: 10, type: !6)
+!63 = !{!"function_entry_count", i64 -1}
+!64 = !DILocation(line: 0, scope: !60)
+!65 = !DILocation(line: 11, column: 6, scope: !66)
+!66 = distinct !DILexicalBlock(scope: !60, file: !3, line: 11, column: 6)
+!67 = !DILocation(line: 11, column: 7, scope: !66)
+!68 = !DILocation(line: 11, column: 6, scope: !60)
+!69 = !DILocation(line: 12, column: 6, scope: !66)
+!70 = !DILocation(line: 12, column: 5, scope: !66)
+!71 = !DILocation(line: 14, column: 5, scope: !60)
+!72 = !DILocation(line: 15, column: 9, scope: !73)
+!73 = distinct !DILexicalBlock(scope: !60, file: !3, line: 15, column: 7)
+!74 = !DILocation(line: 15, column: 7, scope: !60)
+!75 = !DILocation(line: 16, column: 7, scope: !73)
+!76 = !DILocation(line: 16, column: 6, scope: !73)
+!77 = !DILocation(line: 17, column: 12, scope: !78)
+!78 = distinct !DILexicalBlock(scope: !73, file: !3, line: 17, column: 12)
+!79 = !DILocation(line: 17, column: 14, scope: !78)
+!80 = !DILocation(line: 17, column: 12, scope: !73)
+!81 = !DILocation(line: 18, column: 7, scope: !78)
+!82 = !DILocation(line: 18, column: 6, scope: !78)
+!83 = !DILocation(line: 20, column: 7, scope: !78)
+!84 = !DILocation(line: 21, column: 1, scope: !60)
+!85 = distinct !DISubprogram(name: "main", scope: !3, file: !3, line: 23, type: !86, scopeLine: 23, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !2, retainedNodes: !88)
+!86 = !DISubroutineType(types: !87)
+!87 = !{!6}
+!88 = !{!89}
+!89 = !DILocalVariable(name: "i", scope: !85, file: !3, line: 24, type: !6)
+!90 = !{!"function_entry_count", i64 1}
+!91 = !DILocation(line: 24, column: 7, scope: !85)
+!92 = !DILocation(line: 0, scope: !85)
+!93 = !DILocation(line: 25, column: 3, scope: !85)
+!94 = !DILocation(line: 25, column: 11, scope: !85)
+!95 = !DILocation(line: 25, column: 14, scope: !85)
+!96 = !{!"branch_weights", i32 16724, i32 1}
+!97 = !DILocation(line: 26, column: 8, scope: !98)
+!98 = distinct !DILexicalBlock(scope: !99, file: !3, line: 26, column: 8)
+!99 = distinct !DILexicalBlock(scope: !85, file: !3, line: 25, column: 30)
+!100 = !DILocation(line: 26, column: 10, scope: !98)
+!101 = !DILocation(line: 26, column: 8, scope: !99)
+!102 = !{!"branch_weights", i32 14852, i32 1872}
+!103 = !DILocation(line: 27, column: 10, scope: !98)
+!104 = !DILocation(line: 27, column: 6, scope: !105)
+!105 = !DILexicalBlockFile(scope: !98, file: !3, discriminator: 455082031)
+!106 = !{!"branch_weights", i32 14852}
+!107 = !DILocation(line: 27, column: 6, scope: !98)
+!108 = !DILocation(line: 29, column: 10, scope: !98)
+!109 = !DILocation(line: 0, scope: !60, inlinedAt: !110)
+!110 = distinct !DILocation(line: 29, column: 6, scope: !111)
+!111 = !DILexicalBlockFile(scope: !98, file: !3, discriminator: 455082047)
+!112 = !DILocation(line: 11, column: 6, scope: !66, inlinedAt: !110)
+!113 = !DILocation(line: 11, column: 7, scope: !66, inlinedAt: !110)
+!114 = !DILocation(line: 11, column: 6, scope: !60, inlinedAt: !110)
+!115 = !{!"branch_weights", i32 1736, i32 136}
+!116 = !DILocation(line: 12, column: 6, scope: !66, inlinedAt: !110)
+!117 = !DILocation(line: 12, column: 5, scope: !66, inlinedAt: !110)
+!118 = !DILocation(line: 14, column: 5, scope: !60, inlinedAt: !110)
+!119 = !DILocation(line: 15, column: 9, scope: !73, inlinedAt: !110)
+!120 = !DILocation(line: 15, column: 7, scope: !60, inlinedAt: !110)
+!121 = !{!"branch_weights", i32 0, i32 1872}
+!122 = !DILocation(line: 16, column: 7, scope: !73, inlinedAt: !110)
+!123 = !DILocation(line: 16, column: 6, scope: !73, inlinedAt: !110)
+!124 = !DILocation(line: 17, column: 12, scope: !78, inlinedAt: !110)
+!125 = !DILocation(line: 17, column: 14, scope: !78, inlinedAt: !110)
+!126 = !DILocation(line: 17, column: 12, scope: !73, inlinedAt: !110)
+!127 = !{!"branch_weights", i32 936, i32 936}
+!128 = !DILocation(line: 18, column: 7, scope: !78, inlinedAt: !110)
+!129 = !DILocation(line: 18, column: 6, scope: !78, inlinedAt: !110)
+!130 = !DILocation(line: 20, column: 7, scope: !78, inlinedAt: !110)
+!131 = !DILocation(line: 21, column: 1, scope: !60, inlinedAt: !110)
+!132 = distinct !{!132, !93, !133, !134}
+!133 = !DILocation(line: 30, column: 3, scope: !85)
+!134 = !{!"llvm.loop.mustprogress"}
+!135 = !DILocation(line: 31, column: 3,...
[truncated]
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WenleiHe
reviewed
Aug 6, 2024
| @x = dso_local global i32 0, align 4, !dbg !0 | ||
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| ; Function Attrs: noinline nounwind uwtable | ||
| define dso_local void @bar(i32 noundef %i) #0 !dbg !47 !prof !52 { |
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This test case is quite large. Feels like it can be simplified as we only need the input profile to miss a probe?
Also why do we need to have !prof on the input IR? I thought we just want to make sure we have non-zero profile attached after profile loading, so we don't need profile metadata on input, and we don't need --overwrite-existing-weights. Relatedly, we can check !prof of output IR, rather than relying on printing BPI?
There was a problem hiding this comment.
This test case is quite large. Feels like it can be simplified as we only need the input profile to miss a probe?
Also why do we need to have
!profon the input IR? I thought we just want to make sure we have non-zero profile attached after profile loading, so we don't need profile metadata on input, and we don't need--overwrite-existing-weights. Relatedly, we can check!profof output IR, rather than relying on printing BPI?
It's kind of on purpose, for the reason:
-
As mentioned in my last comment, I need an inlined case to repro the "null" return value for
findFunctionSamples, so this needs a post-link IR. Also use--overwrite-existing-weightsto be exactly repro the issue. -
Profile inference(both PROFI or non-PROFI) will try "fix" the unreasonable count, for simple small case, e.g. a simple if-else.
100 100
0 0 unknown unknown
100 100
I can't repro the issue. the unreasonable 0 count is also fixed into a even flow (50 - 50).
Relatedly, we can check !prof of output IR, rather than relying on printing BPI?
Sounds good.
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so this needs a post-link IR. Also use --overwrite-existing-weights to be exactly repro the issue.
ok that works, though I think you can also simply remove the profile metadata on inlined IR, and then you don't need --overwrite-existing-weights.
I found that only for inlined code(not top-level code), (That should be the reason I can't measure any performance change on our regular pipeline) |
the profile annotation part ( |
Yeah, but for pre-link sample loader, we only do inlining when we find the samples, so later we should always find the samples(can't repro the NULL return value) in the same pass. |
WenleiHe
approved these changes
Aug 8, 2024
| @x = dso_local global i32 0, align 4, !dbg !0 | ||
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| ; Function Attrs: noinline nounwind uwtable | ||
| define dso_local void @bar(i32 noundef %i) #0 !dbg !47 !prof !52 { |
There was a problem hiding this comment.
so this needs a post-link IR. Also use --overwrite-existing-weights to be exactly repro the issue.
ok that works, though I think you can also simply remove the profile metadata on inlined IR, and then you don't need --overwrite-existing-weights.
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We should undo this https://reviews.llvm.org/D102007 after undoing https://reviews.llvm.org/D104477 to use missing probe to represent unknown count, zero count and unknown count are different to profile inference.
It only affects post-inline(linker) pipeline(with
--overwrite-existing-weightson ) and flow-sensitive FDO.