Emit the DW_AT_type for a C++ static member definition

if it is more specific than the one in its DW_AT_specification.

If a static member is an array, the translation unit containing the
member definition may have a more specific type (including its length)
than TUs only seeing the class declaration. This patch adds a
DW_AT_type to the member's DW_TAG_variable in addition to the
DW_AT_specification in these cases. The member type in the
DW_AT_specification still shows the more generic type (without the
length) to avoid defeating type uniquing.

The DWARF standard discourages “duplicating” a DW_AT_type in a member
variable definition but doesn’t explicitly forbid it.  Having the more
specific type (with the array length) available is what allows the
debugger to print the contents of a static array member variable.

https://reviews.llvm.org/D26368
rdar://problem/28706946

llvm-svn: 286302

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index 8b5df7c7aef..1aabf69cb1a 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -99,6 +99,10 @@ DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(
     // We need the declaration DIE that is in the static member's class.
     DIE *VariableSpecDIE = getOrCreateStaticMemberDIE(SDMDecl);
     addDIEEntry(*VariableDIE, dwarf::DW_AT_specification, *VariableSpecDIE);
+    // If the global variable's type is different from the one in the class
+    // member type, assume that it's more specific and also emit it.
+    if (GTy != DD->resolve(SDMDecl->getBaseType()))
+      addType(*VariableDIE, GTy);
   } else {
     DeclContext = GV->getScope();
     // Add name and type.