[clang] ce1f95a - Reland "[clang] Remove the DIFlagArgumentNotModified debug info flag"
David Blaikie via cfe-commits
cfe-commits at lists.llvm.org
Thu Dec 26 13:33:04 PST 2019
On Wed, Nov 20, 2019 at 1:08 AM Djordje Todorovic via cfe-commits <
cfe-commits at lists.llvm.org> wrote:
>
> Author: Djordje Todorovic
> Date: 2019-11-20T10:08:07+01:00
> New Revision: ce1f95a6e077693f93d8869245f911aff3eb7e4c
>
> URL:
> https://github.com/llvm/llvm-project/commit/ce1f95a6e077693f93d8869245f911aff3eb7e4c
> DIFF:
> https://github.com/llvm/llvm-project/commit/ce1f95a6e077693f93d8869245f911aff3eb7e4c.diff
>
> LOG: Reland "[clang] Remove the DIFlagArgumentNotModified debug info flag"
>
> 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.
>
What if the LLVM backend optimized out a dead store? (then we might
concnlude that the argument is not modified, when it actually is modified?)
>
> Differential Revision: https://reviews.llvm.org/D68206
>
> Added:
>
>
> Modified:
> clang/lib/CodeGen/CGDebugInfo.cpp
> clang/lib/CodeGen/CGDebugInfo.h
>
> lldb/packages/Python/lldbsuite/test/functionalities/param_entry_vals/basic_entry_values_x86_64/TestBasicEntryValuesX86_64.py
>
> Removed:
> clang/test/CodeGen/debug-info-param-modification.c
>
>
>
> ################################################################################
> diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp
> b/clang/lib/CodeGen/CGDebugInfo.cpp
> index 116517a9cb99..a9b3831aa0b5 100644
> --- a/clang/lib/CodeGen/CGDebugInfo.cpp
> +++ b/clang/lib/CodeGen/CGDebugInfo.cpp
> @@ -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();
> }
>
>
> diff --git a/clang/lib/CodeGen/CGDebugInfo.h
> b/clang/lib/CodeGen/CGDebugInfo.h
> index 9a097615b4b4..5341bfa7f350 100644
> --- a/clang/lib/CodeGen/CGDebugInfo.h
> +++ b/clang/lib/CodeGen/CGDebugInfo.h
> @@ -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;
>
> diff --git a/clang/test/CodeGen/debug-info-param-modification.c
> b/clang/test/CodeGen/debug-info-param-modification.c
> deleted file mode 100644
> index f0a13a3777db..000000000000
> --- a/clang/test/CodeGen/debug-info-param-modification.c
> +++ /dev/null
> @@ -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);
> -}
>
> diff --git
> a/lldb/packages/Python/lldbsuite/test/functionalities/param_entry_vals/basic_entry_values_x86_64/TestBasicEntryValuesX86_64.py
> b/lldb/packages/Python/lldbsuite/test/functionalities/param_entry_vals/basic_entry_values_x86_64/TestBasicEntryValuesX86_64.py
> index e0285e6d626d..1192c2b672f6 100644
> ---
> a/lldb/packages/Python/lldbsuite/test/functionalities/param_entry_vals/basic_entry_values_x86_64/TestBasicEntryValuesX86_64.py
> +++
> b/lldb/packages/Python/lldbsuite/test/functionalities/param_entry_vals/basic_entry_values_x86_64/TestBasicEntryValuesX86_64.py
> @@ -6,7 +6,8 @@
> 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,
>
>
>
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