SamplePGO - Do not count never-executed inlined functions when computing coverage.

If a function was originally inlined but not actually hot at runtime,
its samples will not be counted inside the parent function. This throws
off the coverage calculation because it expects to find more used
records than it should.

Fixed by ignoring functions that will not be inlined into the parent.
Currently, this is inlined functions with 0 samples.  In subsequent
patches, I'll change this to mean "cold" functions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@253716 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/IPO/SampleProfile.cpp b/lib/Transforms/IPO/SampleProfile.cpp
index df8c8a0f7c4ea8bc62a57ebed66e96af2553b6ab..816fc9336d0472d7fb73b79be4d3a31241e7c6df 100644 (file)
--- a/lib/Transforms/IPO/SampleProfile.cpp
+++ b/lib/Transforms/IPO/SampleProfile.cpp
@@ -225,20 +225,39 @@ bool SampleCoverageTracker::markSamplesUsed(const FunctionSamples *Samples,
 unsigned
 SampleCoverageTracker::countUsedSamples(const FunctionSamples *Samples) const {
   auto I = SampleCoverage.find(Samples);
+
+  // The size of the coverage map for Samples represents the number of records
+  // that were marked used at least once.
   unsigned Count = (I != SampleCoverage.end()) ? I->second.size() : 0;
-  for (const auto &I : Samples->getCallsiteSamples())
-    Count += countUsedSamples(&I.second);
+
+  // If there are inlined callsites in this function, count the samples found
+  // in the respective bodies. However, do not bother counting callees with 0
+  // total samples, these are callees that were never invoked at runtime.
+  for (const auto &I : Samples->getCallsiteSamples()) {
+    const FunctionSamples *CalleeSamples = &I.second;
+    if (CalleeSamples->getTotalSamples() > 0)
+      Count += countUsedSamples(&I.second);
+  }
+
   return Count;
 }
 
 /// Return the number of sample records in the body of this profile.
 ///
-/// The count includes all the samples in inlined callees.
+/// The count includes all the samples in inlined callees. However, callsites
+/// with 0 samples indicate inlined function calls that were never actually
+/// invoked at runtime. Ignore these callsites for coverage purposes.
 unsigned
 SampleCoverageTracker::countBodySamples(const FunctionSamples *Samples) const {
   unsigned Count = Samples->getBodySamples().size();
-  for (const auto &I : Samples->getCallsiteSamples())
-    Count += countBodySamples(&I.second);
+
+  // Count all the callsites with non-zero samples.
+  for (const auto &I : Samples->getCallsiteSamples()) {
+    const FunctionSamples *CalleeSamples = &I.second;
+    if (CalleeSamples->getTotalSamples() > 0)
+      Count += countBodySamples(&I.second);
+  }
+
   return Count;
 }
 

diff --git a/test/Transforms/SampleProfile/Inputs/cov-zero-samples.prof b/test/Transforms/SampleProfile/Inputs/cov-zero-samples.prof
new file mode 100644 (file)
index 0000000..528e42c
--- /dev/null
+++ b/test/Transforms/SampleProfile/Inputs/cov-zero-samples.prof
@@ -0,0 +1,10 @@
+main:20111403:0
+ 2.1: 404065
+ 3: 443089
+ 3.1: 0
+ 4: 404066
+ 6: 0
+ 7: 0
+ 3.1: _Z12never_calledi:0
+  0: 0
+  1: 0

diff --git a/test/Transforms/SampleProfile/cov-zero-samples.ll b/test/Transforms/SampleProfile/cov-zero-samples.ll
new file mode 100644 (file)
index 0000000..f7c5f82
--- /dev/null
+++ b/test/Transforms/SampleProfile/cov-zero-samples.ll
@@ -0,0 +1,142 @@
+; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/cov-zero-samples.prof -sample-profile-check-coverage=100 -pass-remarks=sample-profile -o /dev/null 2>&1 | FileCheck %s
+;
+; CHECK: remark: cov-zero-samples.cc:9:25: Applied 404065 samples from profile (offset: 2.1)
+; CHECK: remark: cov-zero-samples.cc:10:9: Applied 443089 samples from profile (offset: 3)
+; CHECK: remark: cov-zero-samples.cc:10:36: Applied 0 samples from profile (offset: 3.1)
+; CHECK: remark: cov-zero-samples.cc:11:12: Applied 404066 samples from profile (offset: 4)
+; CHECK: remark: cov-zero-samples.cc:13:25: Applied 0 samples from profile (offset: 6)
+; CHECK: remark: cov-zero-samples.cc:14:3: Applied 0 samples from profile (offset: 7)
+; CHECK: remark: cov-zero-samples.cc:10:9: most popular destination for conditional branches at cov-zero-samples.cc:9:3
+; CHECK: remark: cov-zero-samples.cc:11:12: most popular destination for conditional branches at cov-zero-samples.cc:10:9
+;
+; Coverage for this profile should be 100%
+; CHECK-NOT: warning: cov-zero-samples.cc:1:
+
+@N = global i64 8000000000, align 8
+@.str = private unnamed_addr constant [11 x i8] c"sum is %d\0A\00", align 1
+
+; Function Attrs: nounwind uwtable
+define i32 @_Z12never_calledi(i32 %i) !dbg !4 {
+entry:
+  ret i32 0, !dbg !32
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+
+; Function Attrs: norecurse uwtable
+define i32 @main() !dbg !8 {
+entry:
+  %retval = alloca i32, align 4
+  %sum = alloca i32, align 4
+  %i = alloca i64, align 8
+  store i32 0, i32* %retval, align 4
+  call void @llvm.dbg.declare(metadata i32* %sum, metadata !33, metadata !19), !dbg !34
+  store i32 0, i32* %sum, align 4, !dbg !34
+  call void @llvm.dbg.declare(metadata i64* %i, metadata !35, metadata !19), !dbg !37
+  store i64 0, i64* %i, align 8, !dbg !37
+  br label %for.cond, !dbg !38
+
+for.cond:                                         ; preds = %for.inc, %entry
+  %0 = load i64, i64* %i, align 8, !dbg !39
+  %1 = load volatile i64, i64* @N, align 8, !dbg !42
+  %cmp = icmp slt i64 %0, %1, !dbg !43
+  br i1 %cmp, label %for.body, label %for.end, !dbg !44
+
+for.body:                                         ; preds = %for.cond
+  %2 = load i64, i64* %i, align 8, !dbg !45
+  %3 = load volatile i64, i64* @N, align 8, !dbg !48
+  %cmp1 = icmp sgt i64 %2, %3, !dbg !49
+  br i1 %cmp1, label %if.then, label %if.end, !dbg !50
+
+if.then:                                          ; preds = %for.body
+  %4 = load i64, i64* %i, align 8, !dbg !51
+  %conv = trunc i64 %4 to i32, !dbg !51
+  %call = call i32 @_Z12never_calledi(i32 %conv), !dbg !53
+  %5 = load i32, i32* %sum, align 4, !dbg !54
+  %add = add nsw i32 %5, %call, !dbg !54
+  store i32 %add, i32* %sum, align 4, !dbg !54
+  br label %if.end, !dbg !55
+
+if.end:                                           ; preds = %if.then, %for.body
+  %6 = load i64, i64* %i, align 8, !dbg !56
+  %div = sdiv i64 %6, 239, !dbg !57
+  %7 = load i32, i32* %sum, align 4, !dbg !58
+  %conv2 = sext i32 %7 to i64, !dbg !58
+  %mul = mul nsw i64 %conv2, %div, !dbg !58
+  %conv3 = trunc i64 %mul to i32, !dbg !58
+  store i32 %conv3, i32* %sum, align 4, !dbg !58
+  br label %for.inc, !dbg !59
+
+for.inc:                                          ; preds = %if.end
+  %8 = load i64, i64* %i, align 8, !dbg !60
+  %inc = add nsw i64 %8, 1, !dbg !60
+  store i64 %inc, i64* %i, align 8, !dbg !60
+  br label %for.cond, !dbg !62
+
+for.end:                                          ; preds = %for.cond
+  %9 = load i32, i32* %sum, align 4, !dbg !63
+  %call4 = call i32 (i8*, ...) @printf(i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str, i32 0, i32 0), i32 %9), !dbg !64
+  ret i32 0, !dbg !65
+}
+
+declare i32 @printf(i8*, ...)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!15, !16}
+!llvm.ident = !{!17}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 3.8.0 (trunk 253667) (llvm/trunk 253670)", isOptimized: false, runtimeVersion: 0, emissionKind: 1, enums: !2, subprograms: !3, globals: !11)
+!1 = !DIFile(filename: "cov-zero-samples.cc", directory: ".")
+!2 = !{}
+!3 = !{!4, !8}
+!4 = distinct !DISubprogram(name: "never_called", linkageName: "_Z12never_calledi", scope: !1, file: !1, line: 5, type: !5, isLocal: false, isDefinition: true, scopeLine: 5, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !7}
+!7 = !DIBasicType(name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!8 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 7, type: !9, isLocal: false, isDefinition: true, scopeLine: 7, flags: DIFlagPrototyped, isOptimized: false, variables: !2)
+!9 = !DISubroutineType(types: !10)
+!10 = !{!7}
+!11 = !{!12}
+!12 = !DIGlobalVariable(name: "N", scope: !0, file: !1, line: 3, type: !13, isLocal: false, isDefinition: true, variable: i64* @N)
+!13 = !DIDerivedType(tag: DW_TAG_volatile_type, baseType: !14)
+!14 = !DIBasicType(name: "long long int", size: 64, align: 64, encoding: DW_ATE_signed)
+!15 = !{i32 2, !"Dwarf Version", i32 4}
+!16 = !{i32 2, !"Debug Info Version", i32 3}
+!17 = !{!"clang version 3.8.0 (trunk 253667) (llvm/trunk 253670)"}
+!19 = !DIExpression()
+!31 = !DILexicalBlockFile(scope: !4, file: !1, discriminator: 3)
+!32 = !DILocation(line: 5, column: 27, scope: !31)
+!33 = !DILocalVariable(name: "sum", scope: !8, file: !1, line: 8, type: !7)
+!34 = !DILocation(line: 8, column: 7, scope: !8)
+!35 = !DILocalVariable(name: "i", scope: !36, file: !1, line: 9, type: !14)
+!36 = distinct !DILexicalBlock(scope: !8, file: !1, line: 9, column: 3)
+!37 = !DILocation(line: 9, column: 18, scope: !36)
+!38 = !DILocation(line: 9, column: 8, scope: !36)
+!39 = !DILocation(line: 9, column: 25, scope: !40)
+!40 = !DILexicalBlockFile(scope: !41, file: !1, discriminator: 1)
+!41 = distinct !DILexicalBlock(scope: !36, file: !1, line: 9, column: 3)
+!42 = !DILocation(line: 9, column: 29, scope: !40)
+!43 = !DILocation(line: 9, column: 27, scope: !40)
+!44 = !DILocation(line: 9, column: 3, scope: !40)
+!45 = !DILocation(line: 10, column: 9, scope: !46)
+!46 = distinct !DILexicalBlock(scope: !47, file: !1, line: 10, column: 9)
+!47 = distinct !DILexicalBlock(scope: !41, file: !1, line: 9, column: 37)
+!48 = !DILocation(line: 10, column: 13, scope: !46)
+!49 = !DILocation(line: 10, column: 11, scope: !46)
+!50 = !DILocation(line: 10, column: 9, scope: !47)
+!51 = !DILocation(line: 10, column: 36, scope: !52)
+!52 = !DILexicalBlockFile(scope: !46, file: !1, discriminator: 1)
+!53 = !DILocation(line: 10, column: 23, scope: !52)
+!54 = !DILocation(line: 10, column: 20, scope: !52)
+!55 = !DILocation(line: 10, column: 16, scope: !52)
+!56 = !DILocation(line: 11, column: 12, scope: !47)
+!57 = !DILocation(line: 11, column: 14, scope: !47)
+!58 = !DILocation(line: 11, column: 9, scope: !47)
+!59 = !DILocation(line: 12, column: 3, scope: !47)
+!60 = !DILocation(line: 9, column: 33, scope: !61)
+!61 = !DILexicalBlockFile(scope: !41, file: !1, discriminator: 2)
+!62 = !DILocation(line: 9, column: 3, scope: !61)
+!63 = !DILocation(line: 13, column: 25, scope: !8)
+!64 = !DILocation(line: 13, column: 3, scope: !8)
+!65 = !DILocation(line: 14, column: 3, scope: !8)