[DebugInfo] DW_OP_deref_size in PrologEpilogInserter.

The PrologEpilogInserter need to insert a DW_OP_deref_size before
prepending a memory location expression to an already implicit
expression to avoid having the existing expression act on the memory
address instead of the value behind it.

The reason for using DW_OP_deref_size and not plain DW_OP_deref is that
big-endian targets need to read the right size as simply truncating a
larger read would yield the wrong result (LSB bytes are not at the lower
address).

Differential Revision: https://reviews.llvm.org/D59687

llvm-svn: 358268

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MIRParser/MIParser.cpp b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
index 971944be2f9..d414b6a0b4b 100644
--- a/llvm/lib/CodeGen/MIRParser/MIParser.cpp
+++ b/llvm/lib/CodeGen/MIRParser/MIParser.cpp
@@ -1854,6 +1854,11 @@ bool MIParser::parseDIExpression(MDNode *&Expr) {
           Elements.push_back(Op);
           continue;
         }
+        if (unsigned Enc = dwarf::getAttributeEncoding(Token.stringValue())) {
+          lex();
+          Elements.push_back(Enc);
+          continue;
+        }
         return error(Twine("invalid DWARF op '") + Token.stringValue() + "'");
       }