[DWARF] Emit DW_AT_call_return_pc as an address

This reverts D53469, which changed llvm's DWARF emission to emit
DW_AT_call_return_pc as a function-local offset. Such an encoding is not
compatible with post-link block re-ordering tools and isn't standards-
compliant.

In addition to reverting back to the original DW_AT_call_return_pc
encoding, teach lldb how to fix up DW_AT_call_return_pc when the address
comes from an object file pointed-to by a debug map. While doing this I
noticed that lldb's support for tail calls that cross a DSO/object file
boundary wasn't covered, so I added tests for that. This latter case
exercises the newly added return PC fixup.

The dsymutil changes in this patch were originally included in D49887:
the associated test should be sufficient to test DW_AT_call_return_pc
encoding purely on the llvm side.

Differential Revision: https://reviews.llvm.org/D72489

1 files changed, 0 insertions, 15 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
index 22f458e..f95c9a3 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
@@ -124,21 +124,6 @@ MCSymbol *DebugHandlerBase::getLabelAfterInsn(const MachineInstr *MI) {
   return LabelsAfterInsn.lookup(MI);
 }
 
-// Return the function-local offset of an instruction.
-const MCExpr *
-DebugHandlerBase::getFunctionLocalOffsetAfterInsn(const MachineInstr *MI) {
-  MCContext &MC = Asm->OutContext;
-
-  MCSymbol *Start = Asm->getFunctionBegin();
-  const auto *StartRef = MCSymbolRefExpr::create(Start, MC);
-
-  MCSymbol *AfterInsn = getLabelAfterInsn(MI);
-  assert(AfterInsn && "Expected label after instruction");
-  const auto *AfterRef = MCSymbolRefExpr::create(AfterInsn, MC);
-
-  return MCBinaryExpr::createSub(AfterRef, StartRef, MC);
-}
-
 /// If this type is derived from a base type then return base type size.
 uint64_t DebugHandlerBase::getBaseTypeSize(const DIType *Ty) {
   assert(Ty);