[PATCH] D70696: [DebugInfo] Support to emit debugInfo for extern variables

[Jaydeep Chauhan via Phabricator via cfe-commits]

Jac1494 added a comment.

For some real life case like below we need debuginfo for declaration of global extern variable .

$cat shlib.c
int var;
int test()
{ return var++; }

$cat test
extern int test();
extern int var;
int main()
{ var++; printf("%d\n",test()); }

If we debug above case with gdb it is not giving types of variable var.
Because of no variable DIE is there in executable.

(gdb) b main
Breakpoint 1 at 0x40063c: file test.c, line 5.
(gdb) pt var
type = <data variable, no debug info>

To add variable debuginfo we need to merge below patch in code.
diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h
index 9a3bb98..df79d46 100644

- a/clang/include/clang/Basic/TargetInfo.h

+++ b/clang/include/clang/Basic/TargetInfo.h
@@ -1371,6 +1371,9 @@ public:

  virtual void setAuxTarget(const TargetInfo *Aux) {}

+  /// Whether target allows debuginfo types for decl only variables.
+  virtual bool allowDebugInfoForExternalVar() const { return true; }
+
protected:

  /// Copy type and layout related info.
  void copyAuxTarget(const TargetInfo *Aux);

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index a61c98e..92245c0 100644

- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp

+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -158,7 +158,11 @@ DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(

  if (!GV->isDefinition())
    addFlag(*VariableDIE, dwarf::DW_AT_declaration);
  else

+  {
+    /*Added location */
+    addLocationAttribute(VariableDIE, GV, GlobalExprs);

  addGlobalName(GV->getName(), *VariableDIE, DeclContext);

+  }

  if (uint32_t AlignInBytes = GV->getAlignInBytes())
    addUInt(*VariableDIE, dwarf::DW_AT_alignment, dwarf::DW_FORM_udata,

@@ -167,9 +171,6 @@ DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(

  if (MDTuple *TP = GV->getTemplateParams())
    addTemplateParams(*VariableDIE, DINodeArray(TP));

- // Add location.
- addLocationAttribute(VariableDIE, GV, GlobalExprs); - return VariableDIE; }




Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D70696/new/

https://reviews.llvm.org/D70696