r364424 - [clang/DIVar] Emit the flag for params that have unmodified value
Djordje Todorovic via cfe-commits
cfe-commits at lists.llvm.org
Wed Jun 26 06:32:02 PDT 2019
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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