[llvm] r190421 - Debug Info: create scope children DIEs when the scope DIE is not null.
Eric Christopher
echristo at gmail.com
Tue Sep 10 11:47:40 PDT 2013
Testcase? How did you see this?
For some of the patch:
+bool DwarfDebug::isLexicalScopeDIENull(LexicalScope *Scope) {
+ if (Scope->isAbstractScope())
Needs a block comment.
+ SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin();
+ MCSymbol *End = getLabelAfterInsn(RI->second);
+ return !End;
Where does this show up?
-eric
On Tue, Sep 10, 2013 at 11:40 AM, Manman Ren <manman.ren at gmail.com> wrote:
> Author: mren
> Date: Tue Sep 10 13:40:41 2013
> New Revision: 190421
>
> URL: http://llvm.org/viewvc/llvm-project?rev=190421&view=rev
> Log:
> Debug Info: create scope children DIEs when the scope DIE is not null.
>
> We try to create the scope children DIEs after we create the scope DIE. But
> to avoid emitting empty lexical block DIE, we first check whether a scope
> DIE is going to be null, then create the scope children if it is not null.
> From the number of children, we decide whether to actually create the scope DIE.
>
> This patch also removes an early exit which checks for a special condition.
> It also removes deletion of un-used children DIEs that are generated
> because we used to generate children DIEs before the scope DIE.
>
> Deletion of un-used children DIEs may cause problem because we sometimes keep
> created DIEs in a member variable of a CU.
>
> Modified:
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp?rev=190421&r1=190420&r2=190421&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.cpp Tue Sep 10 13:40:41 2013
> @@ -424,18 +424,34 @@ DIE *DwarfDebug::updateSubprogramScopeDI
> return SPDie;
> }
>
> +bool DwarfDebug::isLexicalScopeDIENull(LexicalScope *Scope) {
> + if (Scope->isAbstractScope())
> + return false;
> +
> + const SmallVectorImpl<InsnRange> &Ranges = Scope->getRanges();
> + if (Ranges.empty())
> + return true;
> +
> + if (Ranges.size() > 1)
> + return false;
> +
> + SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin();
> + MCSymbol *End = getLabelAfterInsn(RI->second);
> + return !End;
> +}
> +
> // Construct new DW_TAG_lexical_block for this scope and attach
> // DW_AT_low_pc/DW_AT_high_pc labels.
> DIE *DwarfDebug::constructLexicalScopeDIE(CompileUnit *TheCU,
> LexicalScope *Scope) {
> + if (isLexicalScopeDIENull(Scope))
> + return 0;
> +
> DIE *ScopeDIE = new DIE(dwarf::DW_TAG_lexical_block);
> if (Scope->isAbstractScope())
> return ScopeDIE;
>
> const SmallVectorImpl<InsnRange> &Ranges = Scope->getRanges();
> - if (Ranges.empty())
> - return 0;
> -
> // If we have multiple ranges, emit them into the range section.
> if (Ranges.size() > 1) {
> // .debug_range section has not been laid out yet. Emit offset in
> @@ -460,8 +476,7 @@ DIE *DwarfDebug::constructLexicalScopeDI
> SmallVectorImpl<InsnRange>::const_iterator RI = Ranges.begin();
> MCSymbol *Start = getLabelBeforeInsn(RI->first);
> MCSymbol *End = getLabelAfterInsn(RI->second);
> -
> - if (End == 0) return 0;
> + assert(End && "End label should not be null!");
>
> assert(Start->isDefined() && "Invalid starting label for an inlined scope!");
> assert(End->isDefined() && "Invalid end label for an inlined scope!");
> @@ -540,19 +555,9 @@ DIE *DwarfDebug::constructInlinedScopeDI
> return ScopeDIE;
> }
>
> -// Construct a DIE for this scope.
> -DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
> - if (!Scope || !Scope->getScopeNode())
> - return NULL;
> -
> - DIScope DS(Scope->getScopeNode());
> - // Early return to avoid creating dangling variable|scope DIEs.
> - if (!Scope->getInlinedAt() && DS.isSubprogram() && Scope->isAbstractScope() &&
> - !TheCU->getDIE(DS))
> - return NULL;
> -
> - SmallVector<DIE *, 8> Children;
> - DIE *ObjectPointer = NULL;
> +DIE *DwarfDebug::createScopeChildrenDIE(CompileUnit *TheCU, LexicalScope *Scope,
> + SmallVectorImpl<DIE*> &Children) {
> + DIE *ObjectPointer = NULL;
>
> // Collect arguments for current function.
> if (LScopes.isCurrentFunctionScope(Scope))
> @@ -576,6 +581,20 @@ DIE *DwarfDebug::constructScopeDIE(Compi
> for (unsigned j = 0, M = Scopes.size(); j < M; ++j)
> if (DIE *Nested = constructScopeDIE(TheCU, Scopes[j]))
> Children.push_back(Nested);
> + return ObjectPointer;
> +}
> +
> +// Construct a DIE for this scope.
> +DIE *DwarfDebug::constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope) {
> + if (!Scope || !Scope->getScopeNode())
> + return NULL;
> +
> + DIScope DS(Scope->getScopeNode());
> +
> + SmallVector<DIE *, 8> Children;
> + DIE *ObjectPointer = NULL;
> + bool ChildrenCreated = false;
> +
> DIE *ScopeDIE = NULL;
> if (Scope->getInlinedAt())
> ScopeDIE = constructInlinedScopeDIE(TheCU, Scope);
> @@ -591,6 +610,12 @@ DIE *DwarfDebug::constructScopeDIE(Compi
> ScopeDIE = updateSubprogramScopeDIE(TheCU, DS);
> }
> else {
> + if (isLexicalScopeDIENull(Scope))
> + return NULL;
> + // We create children only when we know the scope DIE is not going to be
> + // null.
> + ObjectPointer = createScopeChildrenDIE(TheCU, Scope, Children);
> + ChildrenCreated = true;
> // There is no need to emit empty lexical block DIE.
> std::pair<ImportedEntityMap::const_iterator,
> ImportedEntityMap::const_iterator> Range = std::equal_range(
> @@ -600,15 +625,19 @@ DIE *DwarfDebug::constructScopeDIE(Compi
> if (Children.empty() && Range.first == Range.second)
> return NULL;
> ScopeDIE = constructLexicalScopeDIE(TheCU, Scope);
> + assert(ScopeDIE && "Scope DIE should not be null.");
> for (ImportedEntityMap::const_iterator i = Range.first; i != Range.second;
> ++i)
> constructImportedEntityDIE(TheCU, i->second, ScopeDIE);
> }
>
> if (!ScopeDIE) {
> - std::for_each(Children.begin(), Children.end(), deleter<DIE>);
> + assert(Children.empty() &&
> + "We create children only when the scope DIE is not null.");
> return NULL;
> }
> + if (!ChildrenCreated)
> + ObjectPointer = createScopeChildrenDIE(TheCU, Scope, Children);
>
> // Add children
> for (SmallVectorImpl<DIE *>::iterator I = Children.begin(),
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h?rev=190421&r1=190420&r2=190421&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfDebug.h Tue Sep 10 13:40:41 2013
> @@ -469,6 +469,9 @@ private:
> /// \brief Construct new DW_TAG_lexical_block for this scope and
> /// attach DW_AT_low_pc/DW_AT_high_pc labels.
> DIE *constructLexicalScopeDIE(CompileUnit *TheCU, LexicalScope *Scope);
> + /// A helper function to check whether the DIE for a given Scope is going
> + /// to be null.
> + bool isLexicalScopeDIENull(LexicalScope *Scope);
>
> /// \brief This scope represents inlined body of a function. Construct
> /// DIE to represent this concrete inlined copy of the function.
> @@ -476,6 +479,9 @@ private:
>
> /// \brief Construct a DIE for this scope.
> DIE *constructScopeDIE(CompileUnit *TheCU, LexicalScope *Scope);
> + /// A helper function to create children of a Scope DIE.
> + DIE *createScopeChildrenDIE(CompileUnit *TheCU, LexicalScope *Scope,
> + SmallVectorImpl<DIE*> &Children);
>
> /// \brief Emit initial Dwarf sections with a label at the start of each one.
> void emitSectionLabels();
>
>
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