"sample-profile-max-propagate-iterations", cl::init(100),
cl::desc("Maximum number of iterations to go through when propagating "
"sample block/edge weights through the CFG."));
+static cl::opt<unsigned> SampleProfileCoverage(
+ "sample-profile-check-coverage", cl::init(0), cl::value_desc("N"),
+ cl::desc("Emit a warning if less than N% of samples in the input profile "
+ "are matched to the IR."));
namespace {
typedef DenseMap<const BasicBlock *, uint64_t> BlockWeightMap;
/// \brief Flag indicating whether the profile input loaded successfully.
bool ProfileIsValid;
};
+
+class SampleCoverageTracker {
+public:
+ SampleCoverageTracker() : SampleCoverage() {}
+
+ void markSamplesUsed(const FunctionSamples *Samples, uint32_t LineOffset,
+ uint32_t Discriminator);
+ unsigned computeCoverage(const FunctionSamples *Samples) const;
+ unsigned getNumUsedSamples(const FunctionSamples *Samples) const;
+
+private:
+ typedef DenseMap<LineLocation, unsigned> BodySampleCoverageMap;
+ typedef DenseMap<const FunctionSamples *, BodySampleCoverageMap>
+ FunctionSamplesCoverageMap;
+
+ /// Coverage map for sampling records.
+ ///
+ /// This map keeps a record of sampling records that have been matched to
+ /// an IR instruction. This is used to detect some form of staleness in
+ /// profiles (see flag -sample-profile-check-coverage).
+ ///
+ /// Each entry in the map corresponds to a FunctionSamples instance. This is
+ /// another map that counts how many times the sample record at the
+ /// given location has been used.
+ FunctionSamplesCoverageMap SampleCoverage;
+};
+
+SampleCoverageTracker CoverageTracker;
+}
+
+/// Mark as used the sample record for the given function samples at
+/// (LineOffset, Discriminator).
+void SampleCoverageTracker::markSamplesUsed(const FunctionSamples *Samples,
+ uint32_t LineOffset,
+ uint32_t Discriminator) {
+ BodySampleCoverageMap &Coverage = SampleCoverage[Samples];
+ Coverage[LineLocation(LineOffset, Discriminator)]++;
+}
+
+/// Return the number of sample records that were applied from this profile.
+unsigned
+SampleCoverageTracker::getNumUsedSamples(const FunctionSamples *Samples) const {
+ auto I = SampleCoverage.find(Samples);
+ return (I != SampleCoverage.end()) ? I->second.size() : 0;
+}
+
+/// Return the fraction of sample records used in this profile.
+///
+/// The returned value is an unsigned integer in the range 0-100 indicating
+/// the percentage of sample records that were used while applying this
+/// profile to the associated function.
+unsigned
+SampleCoverageTracker::computeCoverage(const FunctionSamples *Samples) const {
+ uint32_t NumTotalRecords = Samples->getBodySamples().size();
+ uint32_t NumUsedRecords = getNumUsedSamples(Samples);
+ assert(NumUsedRecords <= NumTotalRecords &&
+ "number of used records cannot exceed the total number of records");
+ return NumTotalRecords > 0 ? NumUsedRecords * 100 / NumTotalRecords : 100;
}
/// Clear all the per-function data used to load samples and propagate weights.
unsigned Lineno = DLoc.getLine();
unsigned HeaderLineno = DIL->getScope()->getSubprogram()->getLine();
- ErrorOr<uint64_t> R = FS->findSamplesAt(getOffset(Lineno, HeaderLineno),
- DIL->getDiscriminator());
- if (R)
+ uint32_t LineOffset = getOffset(Lineno, HeaderLineno);
+ uint32_t Discriminator = DIL->getDiscriminator();
+ ErrorOr<uint64_t> R = FS->findSamplesAt(LineOffset, Discriminator);
+ if (R) {
+ if (SampleProfileCoverage)
+ CoverageTracker.markSamplesUsed(FS, LineOffset, Discriminator);
DEBUG(dbgs() << " " << Lineno << "." << DIL->getDiscriminator() << ":"
<< Inst << " (line offset: " << Lineno - HeaderLineno << "."
<< DIL->getDiscriminator() << " - weight: " << R.get()
<< ")\n");
+ }
return R;
}
DEBUG(printBlockWeight(dbgs(), &BB));
}
+ if (SampleProfileCoverage) {
+ unsigned Coverage = CoverageTracker.computeCoverage(Samples);
+ if (Coverage < SampleProfileCoverage) {
+ const char *Filename = getDISubprogram(&F)->getFilename().str().c_str();
+ F.getContext().diagnose(DiagnosticInfoSampleProfile(
+ Filename, getFunctionLoc(F),
+ Twine(CoverageTracker.getNumUsedSamples(Samples)) + " of " +
+ Twine(Samples->getBodySamples().size()) +
+ " available profile records (" + Twine(Coverage) +
+ "%) were applied",
+ DS_Warning));
+ }
+ }
+
return Changed;
}
--- /dev/null
+; RUN: opt < %s -sample-profile -sample-profile-file=%S/Inputs/coverage-warning.prof -sample-profile-check-coverage=90 2>& 1 | FileCheck %s
+define i32 @foo(i32 %i) {
+; The profile has samples for line locations that are no longer present.
+; Coverage does not reach 90%, so we should get this warning:
+;
+; CHECK: warning: coverage-warning.c:1: 2 of 3 available profile records (66%) were applied
+entry:
+ %retval = alloca i32, align 4
+ %i.addr = alloca i32, align 4
+ store i32 %i, i32* %i.addr, align 4
+ %0 = load i32, i32* %i.addr, align 4, !dbg !9
+ %cmp = icmp sgt i32 %0, 1000, !dbg !10
+ br i1 %cmp, label %if.then, label %if.end, !dbg !9
+
+if.then: ; preds = %entry
+ store i32 30, i32* %retval, align 4, !dbg !11
+ br label %return, !dbg !11
+
+if.end: ; preds = %entry
+ store i32 3, i32* %retval, align 4, !dbg !12
+ br label %return, !dbg !12
+
+return: ; preds = %if.end, %if.then
+ %1 = load i32, i32* %retval, align 4, !dbg !13
+ ret i32 %1, !dbg !13
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!6, !7}
+!llvm.ident = !{!8}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 3.8.0 (trunk 251524) (llvm/trunk 251531)", isOptimized: false, runtimeVersion: 0, emissionKind: 2, enums: !2, subprograms: !3)
+!1 = !DIFile(filename: "coverage-warning.c", directory: ".")
+!2 = !{}
+!3 = !{!4}
+!4 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, function: i32 (i32)* @foo, variables: !2)
+!5 = !DISubroutineType(types: !2)
+!6 = !{i32 2, !"Dwarf Version", i32 4}
+!7 = !{i32 2, !"Debug Info Version", i32 3}
+!8 = !{!"clang version 3.8.0 (trunk 251524) (llvm/trunk 251531)"}
+!9 = !DILocation(line: 2, column: 7, scope: !4)
+!10 = !DILocation(line: 2, column: 9, scope: !4)
+!11 = !DILocation(line: 3, column: 5, scope: !4)
+!12 = !DILocation(line: 4, column: 3, scope: !4)
+!13 = !DILocation(line: 5, column: 1, scope: !4)