[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, 10 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
index b19dc4b2506..6e547469c24 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -46,21 +46,26 @@ using namespace llvm;
 
 #define DEBUG_TYPE "dwarfdebug"
 
-DIEDwarfExpression::DIEDwarfExpression(const AsmPrinter &AP, DwarfUnit &DU,
+DIEDwarfExpression::DIEDwarfExpression(const AsmPrinter &AP,
+                                       DwarfCompileUnit &CU,
                                        DIELoc &DIE)
-    : DwarfExpression(AP.getDwarfVersion()), AP(AP), DU(DU),
+    : DwarfExpression(AP.getDwarfVersion(), CU), AP(AP),
       DIE(DIE) {}
 
 void DIEDwarfExpression::emitOp(uint8_t Op, const char* Comment) {
-  DU.addUInt(DIE, dwarf::DW_FORM_data1, Op);
+  CU.addUInt(DIE, dwarf::DW_FORM_data1, Op);
 }
 
 void DIEDwarfExpression::emitSigned(int64_t Value) {
-  DU.addSInt(DIE, dwarf::DW_FORM_sdata, Value);
+  CU.addSInt(DIE, dwarf::DW_FORM_sdata, Value);
 }
 
 void DIEDwarfExpression::emitUnsigned(uint64_t Value) {
-  DU.addUInt(DIE, dwarf::DW_FORM_udata, Value);
+  CU.addUInt(DIE, dwarf::DW_FORM_udata, Value);
+}
+
+void DIEDwarfExpression::emitBaseTypeRef(uint64_t Idx) {
+  CU.addBaseTypeRef(DIE, Idx);
 }
 
 bool DIEDwarfExpression::isFrameRegister(const TargetRegisterInfo &TRI,