[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.

This is a recommit of r356442 with trivial fixes for the failing tests.

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

llvm-svn: 356451

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
index dfc4156243d..f4134da48ca 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DIE.cpp
@@ -506,6 +506,23 @@ LLVM_DUMP_METHOD
 void DIELabel::print(raw_ostream &O) const { O << "Lbl: " << Label->getName(); }
 
 //===----------------------------------------------------------------------===//
+// DIEBaseTypeRef Implementation
+//===----------------------------------------------------------------------===//
+
+void DIEBaseTypeRef::EmitValue(const AsmPrinter *AP, dwarf::Form Form) const {
+  uint64_t Offset = CU->ExprRefedBaseTypes[Index].Die->getOffset();
+  assert(Offset < (1ULL << (ULEB128PadSize * 7)) && "Offset wont fit");
+  AP->EmitULEB128(Offset, nullptr, ULEB128PadSize);
+}
+
+unsigned DIEBaseTypeRef::SizeOf(const AsmPrinter *AP, dwarf::Form Form) const {
+  return ULEB128PadSize;
+}
+
+LLVM_DUMP_METHOD
+void DIEBaseTypeRef::print(raw_ostream &O) const { O << "BaseTypeRef: " << Index; }
+
+//===----------------------------------------------------------------------===//
 // DIEDelta Implementation
 //===----------------------------------------------------------------------===//