paulkirth updated this revision to Diff 215643.
paulkirth edited the summary of this revision.
paulkirth added a comment.
Herald added subscribers: dexonsmith, steven_wu, mehdi_amini.
Removes standalone clang-misexpect from revision
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D66324/new/
https://reviews.llvm.org/D66324
Files:
clang-tools-extra/CMakeLists.txt
clang/include/clang/Basic/CodeGenOptions.def
clang/include/clang/Basic/DiagnosticFrontendKinds.td
clang/include/clang/Basic/DiagnosticGroups.td
clang/include/clang/Driver/Options.td
clang/lib/CodeGen/CGStmt.cpp
clang/lib/CodeGen/CMakeLists.txt
clang/lib/CodeGen/CodeGenAction.cpp
clang/lib/CodeGen/CodeGenFunction.cpp
clang/lib/CodeGen/MisExpect.cpp
clang/lib/CodeGen/MisExpect.h
clang/lib/Driver/ToolChains/Clang.cpp
clang/lib/Frontend/CompilerInvocation.cpp
clang/test/Profile/Inputs/misexpect-branch-nonconst-expect-arg.proftext
clang/test/Profile/Inputs/misexpect-branch.proftext
clang/test/Profile/Inputs/misexpect-switch-default-only.proftext
clang/test/Profile/Inputs/misexpect-switch.proftext
clang/test/Profile/misexpect-branch-cold.c
clang/test/Profile/misexpect-branch-nonconst-expected-val.c
clang/test/Profile/misexpect-branch.c
clang/test/Profile/misexpect-no-warning-without-flag.c
clang/test/Profile/misexpect-switch-default.c
clang/test/Profile/misexpect-switch-nonconst.c
clang/test/Profile/misexpect-switch-only-default-case.c
clang/test/Profile/misexpect-switch.c
llvm/include/llvm/IR/DiagnosticInfo.h
llvm/include/llvm/IR/FixedMetadataKinds.def
llvm/include/llvm/IR/MDBuilder.h
llvm/include/llvm/Transforms/Utils/MisExpect.h
llvm/lib/IR/DiagnosticInfo.cpp
llvm/lib/IR/MDBuilder.cpp
llvm/lib/Transforms/IPO/SampleProfile.cpp
llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
llvm/lib/Transforms/Utils/CMakeLists.txt
llvm/lib/Transforms/Utils/MisExpect.cpp
llvm/test/ThinLTO/X86/lazyload_metadata.ll
llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
Index: llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
===================================================================
--- llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
+++ llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
@@ -138,7 +138,7 @@
%conv1 = sext i32 %conv to i64
%expval = call i64 @llvm.expect.i64(i64 %conv1, i64 0)
%tobool = icmp ne i64 %expval, 0
-; CHECK: !prof !1
+; CHECK: !prof !2
; CHECK-NOT: @llvm.expect
br i1 %tobool, label %if.then, label %if.end
@@ -165,7 +165,7 @@
%tmp = load i32, i32* %x.addr, align 4
%conv = sext i32 %tmp to i64
%expval = call i64 @llvm.expect.i64(i64 %conv, i64 1)
-; CHECK: !prof !2
+; CHECK: !prof !4
; CHECK-NOT: @llvm.expect
switch i64 %expval, label %sw.epilog [
i64 1, label %sw.bb
@@ -194,7 +194,7 @@
%tmp = load i32, i32* %x.addr, align 4
%conv = sext i32 %tmp to i64
%expval = call i64 @llvm.expect.i64(i64 %conv, i64 1)
-; CHECK: !prof !3
+; CHECK: !prof !5
; CHECK-NOT: @llvm.expect
switch i64 %expval, label %sw.epilog [
i64 2, label %sw.bb
@@ -278,7 +278,7 @@
%t7 = call i64 @llvm.expect.i64(i64 %t6, i64 0)
%t8 = icmp ne i64 %t7, 0
%t9 = select i1 %t8, i32 1, i32 2
-; CHECK: select{{.*}}, !prof !1
+; CHECK: select{{.*}}, !prof !2
ret i32 %t9
}
@@ -286,6 +286,6 @@
declare i1 @llvm.expect.i1(i1, i1) nounwind readnone
; CHECK: !0 = !{!"branch_weights", i32 2000, i32 1}
-; CHECK: !1 = !{!"branch_weights", i32 1, i32 2000}
-; CHECK: !2 = !{!"branch_weights", i32 1, i32 2000, i32 1}
-; CHECK: !3 = !{!"branch_weights", i32 2000, i32 1, i32 1}
+; CHECK: !2 = !{!"branch_weights", i32 1, i32 2000}
+; CHECK: !4 = !{!"branch_weights", i32 1, i32 2000, i32 1}
+; CHECK: !5 = !{!"branch_weights", i32 2000, i32 1, i32 1}
Index: llvm/test/ThinLTO/X86/lazyload_metadata.ll
===================================================================
--- llvm/test/ThinLTO/X86/lazyload_metadata.ll
+++ llvm/test/ThinLTO/X86/lazyload_metadata.ll
@@ -10,13 +10,13 @@
; RUN: llvm-lto -thinlto-action=import %t2.bc -thinlto-index=%t3.bc \
; RUN: -o /dev/null -stats \
; RUN: 2>&1 | FileCheck %s -check-prefix=LAZY
-; LAZY: 61 bitcode-reader - Number of Metadata records loaded
+; LAZY: 63 bitcode-reader - Number of Metadata records loaded
; LAZY: 2 bitcode-reader - Number of MDStrings loaded
; RUN: llvm-lto -thinlto-action=import %t2.bc -thinlto-index=%t3.bc \
; RUN: -o /dev/null -disable-ondemand-mds-loading -stats \
; RUN: 2>&1 | FileCheck %s -check-prefix=NOTLAZY
-; NOTLAZY: 70 bitcode-reader - Number of Metadata records loaded
+; NOTLAZY: 72 bitcode-reader - Number of Metadata records loaded
; NOTLAZY: 7 bitcode-reader - Number of MDStrings loaded
Index: llvm/lib/Transforms/Utils/MisExpect.cpp
===================================================================
--- /dev/null
+++ llvm/lib/Transforms/Utils/MisExpect.cpp
@@ -0,0 +1,105 @@
+//===--- MisExpect.cpp - Check Use of __builtin_expect() with PGO data ----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit warnings for potentially incorrect usage of
+// __builtin_expect(). This utility extracts the threshold values from metadata
+// associated with the instrumented Branch or Switch. The threshold values are
+// then used to determin if a warning would be emmited.
+//
+// MisExpect metadata is generated when llvm.expect intrinsics are lowered see
+// LowerExpectIntrinsic.cpp
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/MisExpect.h"
+#include "llvm/ADT/Twine.h"
+#include "llvm/IR/DiagnosticInfo.h"
+#include "llvm/IR/Instruction.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/Support/BranchProbability.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/FormatVariadic.h"
+#include <bits/stdint-uintn.h>
+#include <numeric>
+
+#define DEBUG_TYPE "misexpect"
+
+namespace {
+
+llvm::Instruction *getOprndOrInst(llvm::Instruction *I) {
+ llvm::Instruction *Ret = nullptr;
+ if (auto B = llvm::dyn_cast<llvm::BranchInst>(I)) {
+ Ret = llvm::dyn_cast<llvm::Instruction>(B->getCondition());
+ } else if (auto S = llvm::dyn_cast<llvm::SwitchInst>(I)) {
+ Ret = llvm::dyn_cast<llvm::Instruction>(S->getCondition());
+ }
+ return Ret ? Ret : I;
+}
+
+void emitMisexpectWarning(llvm::Instruction *I, llvm::LLVMContext &Ctx,
+ double PercentageCorrect) {
+ auto PerString = llvm::formatv("{0:P}", PercentageCorrect);
+ llvm::Twine Msg(PerString);
+ llvm::Instruction *Cond = getOprndOrInst(I);
+ Ctx.diagnose(llvm::DiagnosticInfoMisExpect(Cond, Msg));
+}
+
+} // namespace
+
+namespace llvm {
+namespace misexpect {
+
+void verifyMisExpect(Instruction *I, const SmallVector<uint32_t, 4> &Weights,
+ LLVMContext &Ctx) {
+ if (auto *MisExpectData = I->getMetadata(LLVMContext::MD_misexpect)) {
+ auto *MisExpectDataName = dyn_cast<MDString>(MisExpectData->getOperand(0));
+ if (MisExpectDataName &&
+ MisExpectDataName->getString().equals("misexpect")) {
+ LLVM_DEBUG(llvm::dbgs() << "------------------\n");
+ LLVM_DEBUG(llvm::dbgs()
+ << "Function: " << I->getFunction()->getName() << "\n");
+ LLVM_DEBUG(llvm::dbgs() << "Instruction: " << *I << ":\n");
+ LLVM_DEBUG(for (int Idx = 0, Size = Weights.size(); Idx < Size; ++Idx) {
+ llvm::dbgs() << "Weights[" << Idx << "] = " << Weights[Idx] << "\n";
+ });
+ LLVM_DEBUG(llvm::dbgs() << "------------------\n");
+
+ // extract values from misexpect metadata
+ auto *C = mdconst::dyn_extract<ConstantInt>(MisExpectData->getOperand(1));
+ auto *L = mdconst::dyn_extract<ConstantInt>(MisExpectData->getOperand(2));
+ auto *U = mdconst::dyn_extract<ConstantInt>(MisExpectData->getOperand(3));
+
+ uint64_t Index = C->getValue().getZExtValue();
+ uint64_t LikelyBranchWeight = L->getValue().getZExtValue();
+ uint64_t UnlikelyBranchWeight = U->getValue().getZExtValue();
+ uint64_t ProfileCount = Weights[Index];
+ uint64_t CaseTotal =
+ std::accumulate(Weights.begin(), Weights.end(), (uint64_t)0,
+ [](uint64_t W1, uint64_t W2) { return W1 + W2; });
+ int NumUnlikelyTargets = Weights.size() - 2;
+
+ const uint64_t TotalBranchWeight =
+ LikelyBranchWeight + (UnlikelyBranchWeight * NumUnlikelyTargets);
+
+ double Percentage = ((double)ProfileCount / (double)CaseTotal);
+
+ const llvm::BranchProbability LikelyThreshold(LikelyBranchWeight,
+ TotalBranchWeight);
+ auto ScaledThreshold = LikelyThreshold.scale(CaseTotal);
+
+ if (ProfileCount < ScaledThreshold)
+ emitMisexpectWarning(I, Ctx, Percentage);
+ }
+ }
+}
+
+} // namespace misexpect
+} // namespace llvm
+
+#undef DEBUG_TYPE
Index: llvm/lib/Transforms/Utils/CMakeLists.txt
===================================================================
--- llvm/lib/Transforms/Utils/CMakeLists.txt
+++ llvm/lib/Transforms/Utils/CMakeLists.txt
@@ -40,6 +40,7 @@
LowerSwitch.cpp
Mem2Reg.cpp
MetaRenamer.cpp
+ MisExpect.cpp
ModuleUtils.cpp
NameAnonGlobals.cpp
PredicateInfo.cpp
Index: llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
+++ llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
@@ -71,13 +71,15 @@
unsigned n = SI.getNumCases(); // +1 for default case.
SmallVector<uint32_t, 16> Weights(n + 1, UnlikelyBranchWeight);
- if (Case == *SI.case_default())
- Weights[0] = LikelyBranchWeight;
- else
- Weights[Case.getCaseIndex() + 1] = LikelyBranchWeight;
+ uint64_t Index = (Case == *SI.case_default()) ? 0 : Case.getCaseIndex() + 1;
+ Weights[Index] = LikelyBranchWeight;
SI.setMetadata(LLVMContext::MD_prof,
MDBuilder(CI->getContext()).createBranchWeights(Weights));
+ SI.setMetadata(
+ LLVMContext::MD_misexpect,
+ MDBuilder(CI->getContext())
+ .createMisExpect(Index, LikelyBranchWeight, UnlikelyBranchWeight));
SI.setCondition(ArgValue);
return true;
@@ -280,14 +282,19 @@
MDBuilder MDB(CI->getContext());
MDNode *Node;
+ MDNode *ExpNode;
if ((ExpectedValue->getZExtValue() == ValueComparedTo) ==
- (Predicate == CmpInst::ICMP_EQ))
+ (Predicate == CmpInst::ICMP_EQ)) {
Node = MDB.createBranchWeights(LikelyBranchWeight, UnlikelyBranchWeight);
- else
+ ExpNode = MDB.createMisExpect(0, LikelyBranchWeight, UnlikelyBranchWeight);
+ } else {
Node = MDB.createBranchWeights(UnlikelyBranchWeight, LikelyBranchWeight);
+ ExpNode = MDB.createMisExpect(1, LikelyBranchWeight, UnlikelyBranchWeight);
+ }
BSI.setMetadata(LLVMContext::MD_prof, Node);
+ BSI.setMetadata(LLVMContext::MD_misexpect, ExpNode);
if (CmpI)
CmpI->setOperand(0, ArgValue);
Index: llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ llvm/lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -108,6 +108,7 @@
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Instrumentation/PGOInstrumentation.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/MisExpect.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
@@ -1776,6 +1777,9 @@
: Weights) {
dbgs() << W << " ";
} dbgs() << "\n";);
+
+ misexpect::verifyMisExpect(TI, Weights, TI->getContext());
+
TI->setMetadata(LLVMContext::MD_prof, MDB.createBranchWeights(Weights));
if (EmitBranchProbability) {
std::string BrCondStr = getBranchCondString(TI);
Index: llvm/lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -72,6 +72,7 @@
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/CallPromotionUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/MisExpect.h"
#include <algorithm>
#include <cassert>
#include <cstdint>
@@ -1447,6 +1448,8 @@
}
}
+ misexpect::verifyMisExpect(TI, Weights, TI->getContext());
+
uint64_t TempWeight;
// Only set weights if there is at least one non-zero weight.
// In any other case, let the analyzer set weights.
Index: llvm/lib/IR/MDBuilder.cpp
===================================================================
--- llvm/lib/IR/MDBuilder.cpp
+++ llvm/lib/IR/MDBuilder.cpp
@@ -309,3 +309,15 @@
};
return MDNode::get(Context, Vals);
}
+
+MDNode *MDBuilder::createMisExpect(uint64_t Index, uint64_t LikleyWeight,
+ uint64_t UnlikleyWeight) {
+ auto IntType = Type::getInt64Ty(Context);
+ Metadata *Vals[] = {
+ createString("misexpect"),
+ createConstant(ConstantInt::get(IntType, Index)),
+ createConstant(ConstantInt::get(IntType, LikleyWeight)),
+ createConstant(ConstantInt::get(IntType, UnlikleyWeight)),
+ };
+ return MDNode::get(Context, Vals);
+}
Index: llvm/lib/IR/DiagnosticInfo.cpp
===================================================================
--- llvm/lib/IR/DiagnosticInfo.cpp
+++ llvm/lib/IR/DiagnosticInfo.cpp
@@ -370,5 +370,16 @@
return OS.str();
}
+DiagnosticInfoMisExpect::DiagnosticInfoMisExpect(const Instruction *Inst,
+ Twine &Msg)
+ : DiagnosticInfoWithLocationBase(DK_MisExpect, DS_Warning,
+ *Inst->getParent()->getParent(),
+ Inst->getDebugLoc()),
+ Msg(Msg) {}
+
+void DiagnosticInfoMisExpect::print(DiagnosticPrinter &DP) const {
+ DP << getLocationStr() << ": " << getMsg();
+}
+
void OptimizationRemarkAnalysisFPCommute::anchor() {}
void OptimizationRemarkAnalysisAliasing::anchor() {}
Index: llvm/include/llvm/Transforms/Utils/MisExpect.h
===================================================================
--- /dev/null
+++ llvm/include/llvm/Transforms/Utils/MisExpect.h
@@ -0,0 +1,35 @@
+//===--- MisExpect.cpp - Check Use of __builtin_expect() with PGO data ----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit warnings for potentially incorrect usage of
+// __builtin_expect(). This utility extracts the threshold values from metadata
+// associated with the instrumented Branch or Switch. The threshold values are
+// then used to determin if a warning would be emmited.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/LLVMContext.h"
+
+namespace llvm {
+namespace misexpect {
+
+/// verifyMisExpect - compares PGO counters to the thresholds used for
+/// __builtin_expect and warns if the PGO counters are outside of the expected
+/// range.
+/// \param I the Instruction being checked
+/// \param Weights A vector of profile weights for each target block
+/// \param Ctx The current LLVM context
+void verifyMisExpect(llvm::Instruction *I,
+ const llvm::SmallVector<uint32_t, 4> &Weights,
+ llvm::LLVMContext &Ctx);
+
+} // namespace misexpect
+} // namespace llvm
Index: llvm/include/llvm/IR/MDBuilder.h
===================================================================
--- llvm/include/llvm/IR/MDBuilder.h
+++ llvm/include/llvm/IR/MDBuilder.h
@@ -16,6 +16,7 @@
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/StringRef.h"
+#include "llvm/IR/Constants.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/Support/DataTypes.h"
#include <utility>
@@ -75,6 +76,10 @@
/// Return metadata containing the section prefix for a function.
MDNode *createFunctionSectionPrefix(StringRef Prefix);
+ /// return metadata containing expected value
+ MDNode *createMisExpect(uint64_t Index, uint64_t LikelyWeight,
+ uint64_t UnlikelyWeight);
+
//===------------------------------------------------------------------===//
// Range metadata.
//===------------------------------------------------------------------===//
Index: llvm/include/llvm/IR/FixedMetadataKinds.def
===================================================================
--- llvm/include/llvm/IR/FixedMetadataKinds.def
+++ llvm/include/llvm/IR/FixedMetadataKinds.def
@@ -39,3 +39,4 @@
LLVM_FIXED_MD_KIND(MD_access_group, "llvm.access.group", 25)
LLVM_FIXED_MD_KIND(MD_callback, "callback", 26)
LLVM_FIXED_MD_KIND(MD_preserve_access_index, "llvm.preserve.access.index", 27)
+LLVM_FIXED_MD_KIND(MD_misexpect, "misexpect", 28)
Index: llvm/include/llvm/IR/DiagnosticInfo.h
===================================================================
--- llvm/include/llvm/IR/DiagnosticInfo.h
+++ llvm/include/llvm/IR/DiagnosticInfo.h
@@ -75,7 +75,8 @@
DK_MIRParser,
DK_PGOProfile,
DK_Unsupported,
- DK_FirstPluginKind
+ DK_FirstPluginKind,
+ DK_MisExpect
};
/// Get the next available kind ID for a plugin diagnostic.
@@ -1002,6 +1003,31 @@
void print(DiagnosticPrinter &DP) const override;
};
+/// Diagnostic information for MisExpect analysis.
+class DiagnosticInfoMisExpect : public DiagnosticInfoWithLocationBase {
+public:
+ DiagnosticInfoMisExpect(const Function &Fn, const Twine &Msg,
+ const DiagnosticLocation &Loc = DiagnosticLocation(),
+ DiagnosticSeverity Severity = DS_Error)
+ : DiagnosticInfoWithLocationBase(DK_MisExpect, Severity, Fn, Loc),
+ Msg(Msg) {}
+
+ DiagnosticInfoMisExpect(const Instruction *Inst, Twine &Msg);
+
+ /// \see DiagnosticInfo::print.
+ void print(DiagnosticPrinter &DP) const override;
+
+ static bool classof(const DiagnosticInfo *DI) {
+ return DI->getKind() == DK_MisExpect;
+ }
+
+ const Twine &getMsg() const { return Msg; }
+
+private:
+ /// Message to report.
+ const Twine &Msg;
+};
+
} // end namespace llvm
#endif // LLVM_IR_DIAGNOSTICINFO_H
Index: clang/test/Profile/misexpect-switch.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch.c
@@ -0,0 +1,41 @@
+// Test that misexpect detects mis-annotated switch statements
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -fmisexpect
+
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+ init_arry();
+ int val = 0;
+
+ int j, k;
+ for (j = 0; j < outer_loop; ++j) {
+ for (k = 0; k < inner_loop; ++k) {
+ unsigned condition = rand() % 10000;
+ switch (__builtin_expect(condition, 0)) { // expected-warning-re {{Potential performance regression from use of __builtin_expect(): Annotation was correct on {{.+}}% of profiled executions.}}
+ case 0:
+ val += sum(arry, arry_size);
+ break;
+ case 1:
+ case 2:
+ case 3:
+ break;
+ default:
+ val += random_sample(arry, arry_size);
+ break;
+ } // end switch
+ } // end inner_loop
+ } // end outer_loop
+
+ return 0;
+}
Index: clang/test/Profile/misexpect-switch-only-default-case.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch-only-default-case.c
@@ -0,0 +1,35 @@
+// Test that misexpect emits no warning when there is only one switch case
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch-default-only.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -fmisexpect
+
+// expected-no-diagnostics
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+ init_arry();
+ int val = 0;
+
+ int j, k;
+ for (j = 0; j < outer_loop; ++j) {
+ for (k = 0; k < inner_loop; ++k) {
+ unsigned condition = rand() % 10000;
+ switch (__builtin_expect(condition, 0)) {
+ default:
+ val += random_sample(arry, arry_size);
+ break;
+ }; // end switch
+ } // end inner_loop
+ } // end outer_loop
+
+ return 0;
+}
Index: clang/test/Profile/misexpect-switch-nonconst.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch-nonconst.c
@@ -0,0 +1,43 @@
+// Test that misexpect emits no warning when switch condition is non-const
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -fmisexpect
+
+// expected-no-diagnostics
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+ init_arry();
+ int val = 0;
+
+ int j, k;
+ for (j = 0; j < outer_loop; ++j) {
+ for (k = 0; k < inner_loop; ++k) {
+ unsigned condition = rand() % 10000;
+ switch (__builtin_expect(condition, rand())) {
+ case 0:
+ val += sum(arry, arry_size);
+ break;
+ case 1:
+ case 2:
+ case 3:
+ case 4:
+ val += random_sample(arry, arry_size);
+ break;
+ default:
+ __builtin_unreachable();
+ } // end switch
+ } // end inner_loop
+ } // end outer_loop
+
+ return 0;
+}
Index: clang/test/Profile/misexpect-switch-default.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-switch-default.c
@@ -0,0 +1,42 @@
+// Test that misexpect detects mis-annotated switch statements for default case
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-switch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -fmisexpect
+
+int sum(int *buff, int size);
+int random_sample(int *buff, int size);
+int rand();
+void init_arry();
+
+const int inner_loop = 1000;
+const int outer_loop = 20;
+const int arry_size = 25;
+
+int arry[arry_size] = {0};
+
+int main() {
+ init_arry();
+ int val = 0;
+
+ int j, k;
+ for (j = 0; j < outer_loop; ++j) {
+ for (k = 0; k < inner_loop; ++k) {
+ unsigned condition = rand() % 5;
+ switch (__builtin_expect(condition, 6)) { // expected-warning-re {{Potential performance regression from use of __builtin_expect(): Annotation was correct on {{.+}}% of profiled executions.}}
+ case 0:
+ val += sum(arry, arry_size);
+ break;
+ case 1:
+ case 2:
+ case 3:
+ case 4:
+ val += random_sample(arry, arry_size);
+ break;
+ default:
+ __builtin_unreachable();
+ } // end switch
+ } // end inner_loop
+ } // end outer_loop
+
+ return 0;
+}
Index: clang/test/Profile/misexpect-no-warning-without-flag.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-no-warning-without-flag.c
@@ -0,0 +1,27 @@
+// Test that misexpect emits no warning without -fmisexpect flag
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-branch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify
+
+// expected-no-diagnostics
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar() {
+ int rando = buzz();
+ int x = 0;
+ if (likely(rando % (outer_loop * inner_loop) == 0)) {
+ x = baz(rando);
+ } else {
+ x = foo(50);
+ }
+ return x;
+}
+
Index: clang/test/Profile/misexpect-branch.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-branch.c
@@ -0,0 +1,26 @@
+// Test that misexpect detects mis-annotated branches
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-branch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -fmisexpect
+
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar() {
+ int rando = buzz();
+ int x = 0;
+ if (likely(rando % (outer_loop * inner_loop) == 0)) { // expected-warning-re {{Potential performance regression from use of __builtin_expect(): Annotation was correct on {{.+}}% of profiled executions.}}
+ x = baz(rando);
+ } else {
+ x = foo(50);
+ }
+ return x;
+}
+
Index: clang/test/Profile/misexpect-branch-nonconst-expected-val.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-branch-nonconst-expected-val.c
@@ -0,0 +1,26 @@
+// Test that misexpect emits no warning when condition is not a compile-time constant
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-branch-nonconst-expect-arg.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -fmisexpect
+
+// expected-no-diagnostics
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar() {
+ int rando = buzz();
+ int x = 0;
+ if (__builtin_expect(rando % (outer_loop * inner_loop) == 0, buzz())) {
+ x = baz(rando);
+ } else {
+ x = foo(50);
+ }
+ return x;
+}
Index: clang/test/Profile/misexpect-branch-cold.c
===================================================================
--- /dev/null
+++ clang/test/Profile/misexpect-branch-cold.c
@@ -0,0 +1,27 @@
+// Test that misexpect emits no warning when prediction is correct
+
+// RUN: llvm-profdata merge %S/Inputs/misexpect-branch.proftext -o %t.profdata
+// RUN: %clang_cc1 %s -O2 -o - -disable-llvm-passes -emit-llvm -fprofile-instrument-use-path=%t.profdata -verify -fmisexpect
+
+// expected-no-diagnostics
+#define likely(x) __builtin_expect(!!(x), 1)
+#define unlikely(x) __builtin_expect(!!(x), 0)
+
+int foo(int);
+int baz(int);
+int buzz();
+
+const int inner_loop = 100;
+const int outer_loop = 2000;
+
+int bar() {
+ int rando = buzz();
+ int x = 0;
+ if (unlikely(rando % (outer_loop * inner_loop) == 0)) {
+ x = baz(rando);
+ } else {
+ x = foo(50);
+ }
+ return x;
+}
+
Index: clang/test/Profile/Inputs/misexpect-switch.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-switch.proftext
@@ -0,0 +1,16 @@
+main
+# Func Hash:
+1965403898329309329
+# Num Counters:
+9
+# Counter Values:
+1
+20
+20000
+20000
+12
+26
+0
+0
+19962
+
Index: clang/test/Profile/Inputs/misexpect-switch-default-only.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-switch-default-only.proftext
@@ -0,0 +1,12 @@
+main
+# Func Hash:
+79676873694057560
+# Num Counters:
+5
+# Counter Values:
+1
+20
+20000
+20000
+20000
+
Index: clang/test/Profile/Inputs/misexpect-branch.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-branch.proftext
@@ -0,0 +1,9 @@
+bar
+# Func Hash:
+45795613684824
+# Num Counters:
+2
+# Counter Values:
+200000
+0
+
Index: clang/test/Profile/Inputs/misexpect-branch-nonconst-expect-arg.proftext
===================================================================
--- /dev/null
+++ clang/test/Profile/Inputs/misexpect-branch-nonconst-expect-arg.proftext
@@ -0,0 +1,9 @@
+bar
+# Func Hash:
+11262309464
+# Num Counters:
+2
+# Counter Values:
+200000
+2
+
Index: clang/lib/Frontend/CompilerInvocation.cpp
===================================================================
--- clang/lib/Frontend/CompilerInvocation.cpp
+++ clang/lib/Frontend/CompilerInvocation.cpp
@@ -809,6 +809,7 @@
<< Args.getLastArg(OPT_fprofile_remapping_file_EQ)->getAsString(Args)
<< "-fexperimental-new-pass-manager";
}
+ Opts.MisExpect = Args.hasFlag(OPT_fmisexpect, OPT_fno_misexpect, false);
Opts.CoverageMapping =
Args.hasFlag(OPT_fcoverage_mapping, OPT_fno_coverage_mapping, false);
Index: clang/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- clang/lib/Driver/ToolChains/Clang.cpp
+++ clang/lib/Driver/ToolChains/Clang.cpp
@@ -4051,6 +4051,9 @@
Args.AddLastArg(CmdArgs, options::OPT_ffine_grained_bitfield_accesses,
options::OPT_fno_fine_grained_bitfield_accesses);
+ if (Args.hasFlag(options::OPT_fmisexpect, options::OPT_fno_misexpect, false))
+ CmdArgs.push_back("-fmisexpect");
+
// Handle segmented stacks.
if (Args.hasArg(options::OPT_fsplit_stack))
CmdArgs.push_back("-split-stacks");
Index: clang/lib/CodeGen/MisExpect.h
===================================================================
--- /dev/null
+++ clang/lib/CodeGen/MisExpect.h
@@ -0,0 +1,55 @@
+//===--- MisExpect.h - Check Use of __builtin_expect() with PGO data ------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit warnings for potentially incorrect usage of
+// __builtin_expect(). It uses PGO profiles for validation.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_CODEGEN_MISEXPECT_H
+#define LLVM_CLANG_LIB_CODEGEN_MISEXPECT_H
+
+#include "CodeGenModule.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Expr.h"
+#include "clang/Basic/LLVM.h"
+#include "llvm/ADT/Optional.h"
+
+namespace clang {
+namespace CodeGen {
+namespace MisExpect {
+
+/// CheckMisExpectBranch - check if a branch is annotated with
+/// __builtin_expect and when using profiling data, verify that the profile
+/// agrees with the use of the annotation
+/// \param Cond the conditional expression being checked
+/// \param TrueCount the profile counter for this block
+/// \param CurrProfCount the current total profile count
+/// \param CGM a reference to the current CodeGenModule
+void CheckMisExpectBranch(const Expr *Cond, const llvm::BranchInst *BI,
+ uint64_t TrueCount, uint64_t CurrProfCount,
+ CodeGenModule &CGM);
+
+/// CheckMisExpect - check if a branch is annotated with __builtin_expect and
+/// when using profiling data, verify that the profile agrees with the use of
+/// the annotation
+/// \param Call the call expression to __builtin_expect()
+/// \param SwitchWeights pointer to a vector of profile counts for each case arm
+/// \param CaseMap a table mapping the constant value of a case target to its
+/// index in the SwitchWeights vector
+/// \param CGM a reference to the current CodeGenModule
+void CheckMisExpectSwitch(const CallExpr *Call,
+ llvm::SwitchInst *SwitchInstruction,
+ llvm::SmallVector<uint64_t, 16> *SwitchWeights,
+ CodeGenModule &CGM);
+
+} // namespace MisExpect
+} // namespace CodeGen
+} // namespace clang
+
+#endif // LLVM_CLANG_LIB_CODEGEN_MISEXPECT_H
Index: clang/lib/CodeGen/MisExpect.cpp
===================================================================
--- /dev/null
+++ clang/lib/CodeGen/MisExpect.cpp
@@ -0,0 +1,234 @@
+//===--- MisExpect.cpp - Check Use of __builtin_expect() with PGO data ----===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This contains code to emit warnings for potentially incorrect usage of
+// __builtin_expect(). It uses PGO profiles for validation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "MisExpect.h"
+#include "CodeGenModule.h"
+#include "clang/Basic/Builtins.h"
+#include "clang/Basic/CodeGenOptions.h"
+#include "clang/Basic/Diagnostic.h"
+#include "clang/Basic/DiagnosticFrontend.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/Support/BranchProbability.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/FormatVariadic.h"
+#include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
+
+#include <algorithm>
+#include <bits/stdint-intn.h>
+#include <bits/stdint-uintn.h>
+#include <numeric>
+
+#define DEBUG_TYPE "misexpect"
+namespace {
+
+using namespace clang;
+using namespace clang::CodeGen;
+
+struct SwitchDebugInfo {
+ SmallVector<uint64_t, 16> *SwitchWeights;
+ uint64_t ExpectedVal;
+ uint64_t Index;
+ uint64_t TakenCount;
+ uint64_t ScaledThreshold;
+ double Percentage;
+};
+
+// Emit Warning notifying user that the current PGO counter is a mismatch with
+// the use of __builtin_expect()
+// \param PercentageCorrect the percentage the expected target of
+// __builtin_expect() was taken during profiling as an integer
+void EmitMisExpectWarning(const clang::CallExpr *Call, CodeGenModule &CGM,
+ double PercentageCorrect) {
+ SourceLocation ExprLoc = Call->getBeginLoc();
+ auto PercentStr = llvm::formatv("{0:P}", PercentageCorrect).str();
+ CGM.getDiags().Report(ExprLoc, diag::warn_profile_data_misexpect)
+ << PercentStr;
+}
+
+// Prints some debug diagnostics useful when checking SwitchStmts.
+// Allows for simple comparison of the Case Value mappings to their index in the
+// SwitchWeights data structure in CGStmts.cpp
+void DebugPrintMisExpectSwitchInfo(SwitchDebugInfo SDI) {
+ assert(SDI.SwitchWeights && "Null pointer in DebugPrintMisExpectSwitchInfo");
+ LLVM_DEBUG(auto &OS = llvm::dbgs();
+ uint64_t Max = *std::max_element(SDI.SwitchWeights->begin(),
+ SDI.SwitchWeights->end());
+ auto size = SDI.SwitchWeights->size();
+ OS << "------------------\n";
+ for (size_t i = 0; i < size; ++i) {
+ OS << "Index: " << i << "\tProfile Value:\t"
+ << (*SDI.SwitchWeights)[i] << "\n";
+ }
+
+ uint64_t CaseTotal = std::accumulate(SDI.SwitchWeights->begin(),
+ SDI.SwitchWeights->end(), 0);
+ OS << "Profile Count:\t" << CaseTotal << "\n";
+ OS << "Expected Value:\t" << SDI.ExpectedVal << "\n";
+ OS << "Expected Index:\t" << SDI.Index << "\n";
+ OS << "Taken Count:\t" << SDI.TakenCount << "\n";
+ OS << "Max Count:\t" << Max << "\n";
+ OS << "Threshold:\t" << SDI.ScaledThreshold << "\n";
+ OS << llvm::formatv("Ratio: {0}/{1} = {2:P}\n", SDI.TakenCount,
+ CaseTotal, SDI.Percentage);
+ OS << "------------------\n";);
+}
+
+// getExpectedValue - Returns the value that __builtin_expect() is expecting.
+// \param BI the branch instruction being checked
+// \return None if second parameter to __builtin_expect() cannot be evaluated at
+// compile-time, else returns an empty Optional.
+template <class BrSwtchInst>
+llvm::Optional<llvm::ConstantInt *> getExpectedValue(const BrSwtchInst *BI) {
+ // TODO: consider moving funciton into a support lib to improve code reuse
+ if (!BI)
+ return llvm::None;
+
+ const llvm::CallInst *CI;
+ if (const llvm::ICmpInst *CmpI =
+ dyn_cast<llvm::ICmpInst>(BI->getCondition())) {
+ auto CmpConstOperand = dyn_cast<llvm::ConstantInt>(CmpI->getOperand(1));
+ if (!CmpConstOperand)
+ return llvm::None;
+ CI = dyn_cast<llvm::CallInst>(CmpI->getOperand(0));
+ } else {
+ CI = dyn_cast<llvm::CallInst>(BI->getCondition());
+ }
+
+ if (!CI)
+ return llvm::None;
+
+ llvm::Function *Fn = CI->getCalledFunction();
+ if (!Fn || Fn->getIntrinsicID() != llvm::Intrinsic::expect)
+ return llvm::None;
+
+ llvm::ConstantInt *ExpectedValue =
+ dyn_cast<llvm::ConstantInt>(CI->getArgOperand(1));
+
+ if (!ExpectedValue)
+ return llvm::None;
+
+ return ExpectedValue;
+}
+
+} // namespace
+
+namespace clang {
+namespace CodeGen {
+namespace MisExpect {
+
+// TODO: see LowerExpectIntrinsic.cpp for notes on sharing these constants
+const uint32_t LikelyBranchWeight = 2000;
+const uint32_t UnlikelyBranchWeight = 1;
+
+void CheckMisExpectBranch(const Expr *Cond, const llvm::BranchInst *BI,
+ uint64_t TrueCount, uint64_t CurrProfCount,
+ CodeGenModule &CGM) {
+ auto CGOpt = CGM.getCodeGenOpts();
+ if (!CGOpt.MisExpect ||
+ (CGOpt.getProfileUse() == CodeGenOptions::ProfileNone))
+ return;
+
+ auto *Call = dyn_cast<CallExpr>(Cond->IgnoreImpCasts());
+ auto Exp = getExpectedValue(BI);
+
+ if (!Call || !Exp.hasValue())
+ return;
+
+ const long ExpectedVal = Exp.getValue()->getZExtValue();
+ const bool ExpectedTrueBranch = (ExpectedVal != 0);
+ bool IncorrectPerfCounters = false;
+ uint64_t Scaled;
+ double Percentage;
+ const uint64_t TotalBranchWeight = LikelyBranchWeight + UnlikelyBranchWeight;
+
+ // LowerExpectIntrinsics.cpp:49 LikelyBranchWeight = 2000
+ // LowerExpectIntrinsics.cpp:52 UnlikelyBranchWeight = 1
+ if (ExpectedTrueBranch) {
+ const llvm::BranchProbability LikelyThreshold(LikelyBranchWeight,
+ TotalBranchWeight);
+ Scaled = LikelyThreshold.scale(CurrProfCount);
+ Percentage = (TrueCount / (double)CurrProfCount);
+ if (TrueCount < Scaled)
+ IncorrectPerfCounters = true;
+ } else {
+ const llvm::BranchProbability UnlikelyThreshold(UnlikelyBranchWeight,
+ LikelyBranchWeight);
+ Scaled = UnlikelyThreshold.scale(CurrProfCount);
+ Percentage = ((CurrProfCount - TrueCount) / (double)CurrProfCount);
+ if (TrueCount > Scaled)
+ IncorrectPerfCounters = true;
+ }
+
+ LLVM_DEBUG(llvm::dbgs() << "------------------\n");
+ LLVM_DEBUG(llvm::dbgs() << "Function:" << BI->getFunction()->getName()
+ << "\n");
+ LLVM_DEBUG(llvm::dbgs() << "Instruction:" << *BI << "\n");
+
+ LLVM_DEBUG(llvm::dbgs() << "Expected Value:\t" << ExpectedVal << "\n");
+ LLVM_DEBUG(llvm::dbgs() << "Current Count:\t" << CurrProfCount << "\n");
+ LLVM_DEBUG(llvm::dbgs() << "True Count:\t" << TrueCount << "\n");
+ LLVM_DEBUG(llvm::dbgs() << "Scaled Count:\t" << Scaled << "\n");
+ LLVM_DEBUG(llvm::dbgs() << "------------------\n");
+
+ if (IncorrectPerfCounters)
+ EmitMisExpectWarning(Call, CGM, Percentage);
+}
+
+void CheckMisExpectSwitch(const CallExpr *Call, llvm::SwitchInst *SI,
+ SmallVector<uint64_t, 16> *SwitchWeights,
+ CodeGenModule &CGM) {
+ if (!SwitchWeights)
+ return;
+
+ Optional<llvm::ConstantInt *> ExpectedValOpt = getExpectedValue(SI);
+
+ if (!ExpectedValOpt.hasValue())
+ return;
+
+ llvm::ConstantInt *ExpectedValue = ExpectedValOpt.getValue();
+
+ llvm::SwitchInst::CaseHandle Case = *SI->findCaseValue(ExpectedValue);
+ unsigned n = SI->getNumCases(); // +1 for default case.
+
+ // The default case is always mapped to index 0 of the SwitchWeights vector.
+ // This relies on internal details of another component, so ideally we can
+ // expose an interface that we can use instead of relying on implementaion
+ // details in another module.
+ // TODO: create interface to switchweights default index
+ uint64_t Index = (Case == *SI->case_default()) ? 0 : Case.getCaseIndex() + 1;
+ uint64_t TakenCount = (*SwitchWeights)[Index];
+
+ uint64_t CaseTotal =
+ std::accumulate(SwitchWeights->begin(), SwitchWeights->end(), (uint64_t)0,
+ [](uint64_t w1, uint64_t w2) { return w1 + w2; });
+ const uint64_t TotalBranchWeight =
+ LikelyBranchWeight + (UnlikelyBranchWeight * n);
+ double Percentage = ((double)TakenCount / (double)CaseTotal);
+ const llvm::BranchProbability LikelyThreshold(LikelyBranchWeight,
+ TotalBranchWeight);
+ auto ScaledThreshold = LikelyThreshold.scale(CaseTotal);
+
+ LLVM_DEBUG(DebugPrintMisExpectSwitchInfo(
+ {SwitchWeights, ExpectedValue->getZExtValue(), Index, TakenCount,
+ ScaledThreshold, Percentage}));
+
+ if (TakenCount < ScaledThreshold)
+ EmitMisExpectWarning(Call, CGM, Percentage);
+}
+#undef DEBUG_TYPE
+
+} // namespace MisExpect
+} // namespace CodeGen
+} // namespace clang
Index: clang/lib/CodeGen/CodeGenFunction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenFunction.cpp
+++ clang/lib/CodeGen/CodeGenFunction.cpp
@@ -20,6 +20,7 @@
#include "CodeGenModule.h"
#include "CodeGenPGO.h"
#include "TargetInfo.h"
+#include "MisExpect.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/ASTLambda.h"
#include "clang/AST/Decl.h"
@@ -33,6 +34,7 @@
#include "clang/Frontend/FrontendDiagnostic.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Dominators.h"
+#include "llvm/IR/Instructions.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/MDBuilder.h"
#include "llvm/IR/Operator.h"
@@ -1360,8 +1362,6 @@
return true;
}
-
-
/// EmitBranchOnBoolExpr - Emit a branch on a boolean condition (e.g. for an if
/// statement) to the specified blocks. Based on the condition, this might try
/// to simplify the codegen of the conditional based on the branch.
@@ -1558,7 +1558,9 @@
ApplyDebugLocation DL(*this, Cond);
CondV = EvaluateExprAsBool(Cond);
}
- Builder.CreateCondBr(CondV, TrueBlock, FalseBlock, Weights, Unpredictable);
+ llvm::BranchInst *BI = Builder.CreateCondBr(CondV, TrueBlock, FalseBlock,
+ Weights, Unpredictable);
+ MisExpect::CheckMisExpectBranch(Cond, BI, TrueCount, CurrentCount, CGM);
}
/// ErrorUnsupported - Print out an error that codegen doesn't support the
Index: clang/lib/CodeGen/CodeGenAction.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenAction.cpp
+++ clang/lib/CodeGen/CodeGenAction.cpp
@@ -14,6 +14,7 @@
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclCXX.h"
#include "clang/AST/DeclGroup.h"
+#include "clang/Basic/DiagnosticFrontend.h"
#include "clang/Basic/FileManager.h"
#include "clang/Basic/LangStandard.h"
#include "clang/Basic/SourceManager.h"
@@ -363,6 +364,7 @@
bool StackSizeDiagHandler(const llvm::DiagnosticInfoStackSize &D);
/// Specialized handler for unsupported backend feature diagnostic.
void UnsupportedDiagHandler(const llvm::DiagnosticInfoUnsupported &D);
+ void MisExpectDiagHandler(const llvm::DiagnosticInfoMisExpect &D);
/// Specialized handlers for optimization remarks.
/// Note that these handlers only accept remarks and they always handle
/// them.
@@ -615,6 +617,25 @@
<< Filename << Line << Column;
}
+void BackendConsumer::MisExpectDiagHandler(
+ const llvm::DiagnosticInfoMisExpect &D) {
+ StringRef Filename;
+ unsigned Line, Column;
+ bool BadDebugInfo = false;
+ FullSourceLoc Loc =
+ getBestLocationFromDebugLoc(D, BadDebugInfo, Filename, Line, Column);
+
+ Diags.Report(Loc, diag::warn_profile_data_misexpect) << D.getMsg().str();
+
+ if (BadDebugInfo)
+ // If we were not able to translate the file:line:col information
+ // back to a SourceLocation, at least emit a note stating that
+ // we could not translate this location. This can happen in the
+ // case of #line directives.
+ Diags.Report(Loc, diag::note_fe_backend_invalid_loc)
+ << Filename << Line << Column;
+}
+
void BackendConsumer::EmitOptimizationMessage(
const llvm::DiagnosticInfoOptimizationBase &D, unsigned DiagID) {
// We only support warnings and remarks.
@@ -785,6 +806,9 @@
case llvm::DK_Unsupported:
UnsupportedDiagHandler(cast<DiagnosticInfoUnsupported>(DI));
return;
+ case llvm::DK_MisExpect:
+ MisExpectDiagHandler(cast<DiagnosticInfoMisExpect>(DI));
+ return;
default:
// Plugin IDs are not bound to any value as they are set dynamically.
ComputeDiagRemarkID(Severity, backend_plugin, DiagID);
Index: clang/lib/CodeGen/CMakeLists.txt
===================================================================
--- clang/lib/CodeGen/CMakeLists.txt
+++ clang/lib/CodeGen/CMakeLists.txt
@@ -87,6 +87,7 @@
ItaniumCXXABI.cpp
MacroPPCallbacks.cpp
MicrosoftCXXABI.cpp
+ MisExpect.cpp
ModuleBuilder.cpp
ObjectFilePCHContainerOperations.cpp
PatternInit.cpp
Index: clang/lib/CodeGen/CGStmt.cpp
===================================================================
--- clang/lib/CodeGen/CGStmt.cpp
+++ clang/lib/CodeGen/CGStmt.cpp
@@ -14,6 +14,7 @@
#include "CGDebugInfo.h"
#include "CodeGenModule.h"
#include "TargetInfo.h"
+#include "MisExpect.h"
#include "clang/AST/StmtVisitor.h"
#include "clang/Basic/Builtins.h"
#include "clang/Basic/PrettyStackTrace.h"
@@ -1698,10 +1699,15 @@
auto *Call = dyn_cast<CallExpr>(S.getCond());
if (Call && CGM.getCodeGenOpts().OptimizationLevel != 0) {
auto *FD = dyn_cast_or_null<FunctionDecl>(Call->getCalleeDecl());
- if (FD && FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) {
- llvm::MDBuilder MDHelper(getLLVMContext());
- SwitchInsn->setMetadata(llvm::LLVMContext::MD_unpredictable,
- MDHelper.createUnpredictable());
+ if (FD) {
+ if (FD->getBuiltinID() == Builtin::BI__builtin_unpredictable) {
+ llvm::MDBuilder MDHelper(getLLVMContext());
+ SwitchInsn->setMetadata(llvm::LLVMContext::MD_unpredictable,
+ MDHelper.createUnpredictable());
+ } else if (CGM.getCodeGenOpts().MisExpect &&
+ FD->getBuiltinID() == Builtin::BI__builtin_expect) {
+ MisExpect::CheckMisExpectSwitch(Call, SwitchInsn, SwitchWeights, CGM);
+ }
}
}
Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -716,6 +716,11 @@
Group<f_Group>, Alias<fprofile_sample_accurate>;
def fno_auto_profile_accurate : Flag<["-"], "fno-auto-profile-accurate">,
Group<f_Group>, Alias<fno_profile_sample_accurate>;
+def fmisexpect : Flag<["-"], "fmisexpect">,
+ Group<f_Group>, Flags<[CC1Option]>,
+ HelpText<"Validate use of __builtin_expect with instrumentation data">;
+def fno_misexpect : Flag<["-"], "fno-misexpect">,
+ Group<f_Group>, Flags<[CC1Option]>;
def fdebug_compilation_dir : Separate<["-"], "fdebug-compilation-dir">,
Group<f_Group>, Flags<[CC1Option, CC1AsOption, CoreOption]>,
HelpText<"The compilation directory to embed in the debug info.">;
Index: clang/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- clang/include/clang/Basic/DiagnosticGroups.td
+++ clang/include/clang/Basic/DiagnosticGroups.td
@@ -1031,6 +1031,7 @@
def ProfileInstrMissing : DiagGroup<"profile-instr-missing">;
def ProfileInstrOutOfDate : DiagGroup<"profile-instr-out-of-date">;
def ProfileInstrUnprofiled : DiagGroup<"profile-instr-unprofiled">;
+def MisExpect : DiagGroup<"misexpect">;
// AddressSanitizer frontend instrumentation remarks.
def SanitizeAddressRemarks : DiagGroup<"sanitize-address">;
Index: clang/include/clang/Basic/DiagnosticFrontendKinds.td
===================================================================
--- clang/include/clang/Basic/DiagnosticFrontendKinds.td
+++ clang/include/clang/Basic/DiagnosticFrontendKinds.td
@@ -275,6 +275,10 @@
def warn_profile_data_unprofiled : Warning<
"no profile data available for file \"%0\"">,
InGroup<ProfileInstrUnprofiled>;
+def warn_profile_data_misexpect : Warning<
+ "Potential performance regression from use of __builtin_expect(): "
+ "Annotation was correct on %0 of profiled executions.">,
+ InGroup<MisExpect>;
} // end of instrumentation issue category
Index: clang/include/clang/Basic/CodeGenOptions.def
===================================================================
--- clang/include/clang/Basic/CodeGenOptions.def
+++ clang/include/clang/Basic/CodeGenOptions.def
@@ -169,6 +169,7 @@
///< enable code coverage analysis.
CODEGENOPT(DumpCoverageMapping , 1, 0) ///< Dump the generated coverage mapping
///< regions.
+CODEGENOPT(MisExpect , 1, 0) ///< Validate __builtin_expect with PGO counters
/// If -fpcc-struct-return or -freg-struct-return is specified.
ENUM_CODEGENOPT(StructReturnConvention, StructReturnConventionKind, 2, SRCK_Default)
Index: clang-tools-extra/CMakeLists.txt
===================================================================
--- clang-tools-extra/CMakeLists.txt
+++ clang-tools-extra/CMakeLists.txt
@@ -5,6 +5,7 @@
add_subdirectory(modularize)
add_subdirectory(clang-tidy)
add_subdirectory(clang-tidy-vs)
+add_subdirectory(clang-misexpect)
add_subdirectory(clang-change-namespace)
add_subdirectory(clang-doc)
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