r364424 - [clang/DIVar] Emit the flag for params that have unmodified value
Vedant Kumar via cfe-commits
cfe-commits at lists.llvm.org
Wed Jul 10 17:11:04 PDT 2019
Hi Djordje,
Just a heads-up that I’ve landed r365716 to fix a crash in a stage2 build of AppleClang with -femit-debug-entry-values enabled.
I went ahead and landed the fix as it seemed simple enough. Let me know if you have any concerns.
Thanks,
Vedant
> On Jun 26, 2019, at 6:32 AM, Djordje Todorovic via cfe-commits <cfe-commits at lists.llvm.org> wrote:
>
> Author: djtodoro
> Date: Wed Jun 26 06:32:02 2019
> New Revision: 364424
>
> URL: http://llvm.org/viewvc/llvm-project?rev=364424&view=rev
> Log:
> [clang/DIVar] Emit the flag for params that have unmodified value
>
> Emit the debug info flag that indicates that a parameter has unchanged
> value throughout a function.
>
> ([5/13] Introduce the debug entry values.)
>
> Co-authored-by: Ananth Sowda <asowda at cisco.com>
> Co-authored-by: Nikola Prica <nikola.prica at rt-rk.com>
> Co-authored-by: Ivan Baev <ibaev at cisco.com>
>
> Differential Revision: https://reviews.llvm.org/D58035
>
> Added:
> cfe/trunk/test/CodeGen/debug-info-param-modification.c
> Modified:
> cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
> cfe/trunk/lib/CodeGen/CGDebugInfo.h
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.cpp?rev=364424&r1=364423&r2=364424&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.cpp (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.cpp Wed Jun 26 06:32:02 2019
> @@ -18,6 +18,7 @@
> #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"
> @@ -3588,6 +3589,12 @@ void CGDebugInfo::EmitFunctionStart(Glob
> 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.
> + if (CGM.getCodeGenOpts().EnableDebugEntryValues && HasDecl &&
> + isa<FunctionDecl>(D))
> + SPDefCache[cast<FunctionDecl>(D)].reset(SP);
> +
> if (CGM.getCodeGenOpts().DwarfVersion >= 5) {
> // Starting with DWARF V5 method declarations are emitted as children of
> // the interface type.
> @@ -3964,6 +3971,11 @@ llvm::DILocalVariable *CGDebugInfo::Emit
> 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;
> }
>
> @@ -4555,6 +4567,29 @@ void CGDebugInfo::setDwoId(uint64_t Sign
> 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.
> @@ -4627,6 +4662,10 @@ 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();
> }
>
>
> Modified: cfe/trunk/lib/CodeGen/CGDebugInfo.h
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDebugInfo.h?rev=364424&r1=364423&r2=364424&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/CGDebugInfo.h (original)
> +++ cfe/trunk/lib/CodeGen/CGDebugInfo.h Wed Jun 26 06:32:02 2019
> @@ -134,6 +134,10 @@ 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;
>
> Added: cfe/trunk/test/CodeGen/debug-info-param-modification.c
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/debug-info-param-modification.c?rev=364424&view=auto
> ==============================================================================
> --- cfe/trunk/test/CodeGen/debug-info-param-modification.c (added)
> +++ cfe/trunk/test/CodeGen/debug-info-param-modification.c Wed Jun 26 06:32:02 2019
> @@ -0,0 +1,12 @@
> +// RUN: %clang -Xclang -femit-debug-entry-values -g -O2 -S -target x86_64-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)
> +//
> +// RUN: %clang -g -O2 -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)
> +//
> +
> +int fn2 (int a, int b) {
> + ++a;
> + return b;
> +}
>
>
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