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Reland "[clang] Remove the DIFlagArgumentNotModified debug info flag"

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It turns out that the ExprMutationAnalyzer can be very slow when AST
gets huge in some cases. The idea is to move this analysis to the LLVM
back-end level (more precisely, in the LiveDebugValues pass). The new
approach will remove the performance regression, simplify the
implementation and give us front-end independent implementation.

Differential Revision: https://reviews.llvm.org/D68206
This commit is contained in:
Djordje Todorovic 2019-11-19 14:47:08 +01:00
parent dc3ee33089
commit ce1f95a6e0
4 changed files with 2 additions and 72 deletions
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42
clang/lib/CodeGen/CGDebugInfo.cpp
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@ -18,7 +18,6 @@
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "ConstantEmitter.h"
#include "clang/Analysis/Analyses/ExprMutationAnalyzer.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/DeclFriend.h"
#include "clang/AST/DeclObjC.h"
@ -3686,15 +3685,6 @@ void CGDebugInfo::EmitFunctionStart(GlobalDecl GD, SourceLocation Loc,
if (HasDecl && isa<FunctionDecl>(D))
DeclCache[D->getCanonicalDecl()].reset(SP);
// We use the SPDefCache only in the case when the debug entry values option
// is set, in order to speed up parameters modification analysis.
//
// FIXME: Use AbstractCallee here to support ObjCMethodDecl.
if (CGM.getCodeGenOpts().EnableDebugEntryValues && HasDecl)
if (auto *FD = dyn_cast<FunctionDecl>(D))
if (FD->hasBody() && !FD->param_empty())
SPDefCache[FD].reset(SP);
// Push the function onto the lexical block stack.
LexicalBlockStack.emplace_back(SP);
@ -4097,11 +4087,6 @@ llvm::DILocalVariable *CGDebugInfo::EmitDeclare(const VarDecl *VD,
llvm::DebugLoc::get(Line, Column, Scope, CurInlinedAt),
Builder.GetInsertBlock());
if (CGM.getCodeGenOpts().EnableDebugEntryValues && ArgNo) {
if (auto *PD = dyn_cast<ParmVarDecl>(VD))
ParamCache[PD].reset(D);
}
return D;
}
@ -4717,29 +4702,6 @@ void CGDebugInfo::setDwoId(uint64_t Signature) {
TheCU->setDWOId(Signature);
}
/// Analyzes each function parameter to determine whether it is constant
/// throughout the function body.
static void analyzeParametersModification(
ASTContext &Ctx,
llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> &SPDefCache,
llvm::DenseMap<const ParmVarDecl *, llvm::TrackingMDRef> &ParamCache) {
for (auto &SP : SPDefCache) {
auto *FD = SP.first;
assert(FD->hasBody() && "Functions must have body here");
const Stmt *FuncBody = (*FD).getBody();
for (auto Parm : FD->parameters()) {
ExprMutationAnalyzer FuncAnalyzer(*FuncBody, Ctx);
if (FuncAnalyzer.isMutated(Parm))
continue;
auto I = ParamCache.find(Parm);
assert(I != ParamCache.end() && "Parameters should be already cached");
auto *DIParm = cast<llvm::DILocalVariable>(I->second);
DIParm->setIsNotModified();
}
}
}
void CGDebugInfo::finalize() {
// Creating types might create further types - invalidating the current
// element and the size(), so don't cache/reference them.
@ -4812,10 +4774,6 @@ void CGDebugInfo::finalize() {
if (auto MD = TypeCache[RT])
DBuilder.retainType(cast<llvm::DIType>(MD));
if (CGM.getCodeGenOpts().EnableDebugEntryValues)
// This will be used to emit debug entry values.
analyzeParametersModification(CGM.getContext(), SPDefCache, ParamCache);
DBuilder.finalize();
}

4
clang/lib/CodeGen/CGDebugInfo.h
View File

@ -146,10 +146,6 @@ class CGDebugInfo {
llvm::DenseMap<const char *, llvm::TrackingMDRef> DIFileCache;
llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> SPCache;
/// Cache function definitions relevant to use for parameters mutation
/// analysis.
llvm::DenseMap<const FunctionDecl *, llvm::TrackingMDRef> SPDefCache;
llvm::DenseMap<const ParmVarDecl *, llvm::TrackingMDRef> ParamCache;
/// Cache declarations relevant to DW_TAG_imported_declarations (C++
/// using declarations) that aren't covered by other more specific caches.
llvm::DenseMap<const Decl *, llvm::TrackingMDRef> DeclCache;

25
clang/test/CodeGen/debug-info-param-modification.c
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@ -1,25 +0,0 @@
// RUN: %clang -Xclang -femit-debug-entry-values -g -O2 -Xclang -disable-llvm-passes -S -target x86_64-none-linux-gnu -emit-llvm %s -o - | FileCheck %s -check-prefix=CHECK-ENTRY-VAL-OPT
// RUN: %clang -Xclang -femit-debug-entry-values -g -O2 -Xclang -disable-llvm-passes -S -target arm-none-linux-gnu -emit-llvm %s -o - | FileCheck %s -check-prefix=CHECK-ENTRY-VAL-OPT
// RUN: %clang -Xclang -femit-debug-entry-values -g -O2 -Xclang -disable-llvm-passes -S -target aarch64-none-linux-gnu -emit-llvm %s -o - | FileCheck %s -check-prefix=CHECK-ENTRY-VAL-OPT
// RUN: %clang -Xclang -femit-debug-entry-values -g -O2 -Xclang -disable-llvm-passes -S -target armeb-none-linux-gnu -emit-llvm %s -o - | FileCheck %s -check-prefix=CHECK-ENTRY-VAL-OPT
// CHECK-ENTRY-VAL-OPT: !DILocalVariable(name: "a", arg: 1, scope: {{.*}}, file: {{.*}}, line: {{.*}}, type: {{.*}})
// CHECK-ENTRY-VAL-OPT: !DILocalVariable(name: "b", arg: 2, scope: {{.*}}, file: {{.*}}, line: {{.*}}, type: {{.*}}, flags: DIFlagArgumentNotModified)
//
// For the os_log_helper:
// CHECK-ENTRY-VAL-OPT: !DILocalVariable(name: "buffer", arg: 1, {{.*}}, flags: DIFlagArtificial)
//
// RUN: %clang -g -O2 -Xclang -disable-llvm-passes -target x86_64-none-linux-gnu -S -emit-llvm %s -o - | FileCheck %s
// CHECK-NOT: !DILocalVariable(name: "b", arg: 2, scope: {{.*}}, file: {{.*}}, line: {{.*}}, type: {{.*}}, flags: DIFlagArgumentNotModified)
//
// For the os_log_helper:
// CHECK: !DILocalVariable(name: "buffer", arg: 1, {{.*}}, flags: DIFlagArtificial)
int fn2 (int a, int b) {
++a;
return b;
}
void test_builtin_os_log(void *buf, int i, const char *data) {
__builtin_os_log_format(buf, "%d %{public}s %{private}.16P", i, data, data);
}

3
lldb/packages/Python/lldbsuite/test/functionalities/param_entry_vals/basic_entry_values_x86_64/TestBasicEntryValuesX86_64.py
View File

@ -6,7 +6,8 @@ supported_platforms = ["linux"]
supported_platforms.extend(lldbplatformutil.getDarwinOSTriples())
lldbinline.MakeInlineTest(__file__, globals(),
[decorators.skipUnlessPlatform(supported_platforms),
[decorators.skipIf(bugnumber="llvm.org/pr44059"),
decorators.skipUnlessPlatform(supported_platforms),
decorators.skipIf(compiler="clang", compiler_version=['<', '10.0']),
decorators.skipUnlessArch('x86_64'),
decorators.skipUnlessHasCallSiteInfo,