Debug Info: Move the complex expression handling (=the remainder) of

emitDebugLocValue() into DwarfExpression.

Ought to be NFC, but it actually uncovered a bug in the debug-loc-asan.ll
testcase. The testcase checks that the address of variable "y" is stored
at [RSP+16], which also lines up with the comment.
It also check(ed) that the *value* of "y" is stored in RDI before that,
but that is actually incorrect, since RDI is the very value that is
stored in [RSP+16]. Here's the assembler output:

	movb	2147450880(%rcx), %r8b
	#DEBUG_VALUE: bar:y <- RDI
	cmpb	$0, %r8b
	movq	%rax, 32(%rsp)          # 8-byte Spill
	movq	%rsi, 24(%rsp)          # 8-byte Spill
	movq	%rdi, 16(%rsp)          # 8-byte Spill
.Ltmp3:
	#DEBUG_VALUE: bar:y <- [RSP+16]

Fixed the comment to spell out the correct register and the check to
expect an address rather than a value.

Note that the range that is emitted for the RDI location was and is still
wrong, it claims to begin at the function prologue, but really it should
start where RDI is first assigned.

llvm-svn: 225851

1 files changed, 2 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index d2dab370ec0..5d1fbb5a7a9 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -565,7 +565,8 @@ public:
   void emitDebugLocEntry(ByteStreamer &Streamer, const DebugLocEntry &Entry);
   /// \brief emit a single value for the debug loc section.
   void emitDebugLocValue(ByteStreamer &Streamer,
-                         const DebugLocEntry::Value &Value);
+                         const DebugLocEntry::Value &Value,
+                         unsigned PieceOffsetInBits = 0);
   /// Emits an optimal (=sorted) sequence of DW_OP_pieces.
   void emitLocPieces(ByteStreamer &Streamer,
                      const DITypeIdentifierMap &Map,