[DebugInfo] Introduce DW_OP_LLVM_convert

Introduce a DW_OP_LLVM_convert Dwarf expression pseudo op that allows
for a convenient way to perform type conversions on the Dwarf expression
stack. As an additional bonus it paves the way for using other Dwarf
v5 ops that need to reference a base_type.

The new DW_OP_LLVM_convert is used from lib/Transforms/Utils/Local.cpp
to perform sext/zext on debug values but mainly the patch is about
preparing terrain for adding other Dwarf v5 ops that need to reference a
base_type.

For Dwarf v5 the op maps to DW_OP_convert and for earlier versions a
complex shift & mask pattern is generated to emulate sext/zext.

Differential Revision: https://reviews.llvm.org/D56587

llvm-svn: 356442

1 files changed, 14 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
index c5ec49503c6..d9addb52376 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.h
@@ -124,6 +124,16 @@ public:
     const DIExpression *Expr;
   };
 
+  struct BaseTypeRef {
+    BaseTypeRef(unsigned BitSize, dwarf::TypeKind Encoding) :
+      BitSize(BitSize), Encoding(Encoding) {}
+    unsigned BitSize;
+    dwarf::TypeKind Encoding;
+    DIE *Die = nullptr;
+  };
+
+  std::vector<BaseTypeRef> ExprRefedBaseTypes;
+
   /// Get or create global variable DIE.
   DIE *
   getOrCreateGlobalVariableDIE(const DIGlobalVariable *GV,
@@ -199,6 +209,8 @@ public:
                               SmallVectorImpl<DIE *> &Children,
                               bool *HasNonScopeChildren = nullptr);
 
+  void createBaseTypeDIEs();
+
   /// Construct a DIE for this subprogram scope.
   DIE &constructSubprogramScopeDIE(const DISubprogram *Sub,
                                    LexicalScope *Scope);
@@ -313,6 +325,8 @@ public:
   void setDWOId(uint64_t DwoId) { DWOId = DwoId; }
 
   bool hasDwarfPubSections() const;
+
+  void addBaseTypeRef(DIEValueList &Die, int64_t Idx);
 };
 
 } // end namespace llvm