[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).
This re-commit fixes issues reported in the first one. Namely deref was
inserted under wrong conditions and additionally the deref_size argument
was incorrectly encoded.
Differential Revision: https://reviews.llvm.org/D59687
llvm-svn: 359535
diff --git a/llvm/lib/IR/DebugInfoMetadata.cpp b/llvm/lib/IR/DebugInfoMetadata.cpp
index 7158e57..4ef38b6 100644
--- a/llvm/lib/IR/DebugInfoMetadata.cpp
+++ b/llvm/lib/IR/DebugInfoMetadata.cpp
@@ -833,6 +833,7 @@
case dwarf::DW_OP_LLVM_fragment:
return 3;
case dwarf::DW_OP_constu:
+ case dwarf::DW_OP_deref_size:
case dwarf::DW_OP_plus_uconst:
return 2;
default:
@@ -889,6 +890,7 @@
case dwarf::DW_OP_shr:
case dwarf::DW_OP_shra:
case dwarf::DW_OP_deref:
+ case dwarf::DW_OP_deref_size:
case dwarf::DW_OP_xderef:
case dwarf::DW_OP_lit0:
case dwarf::DW_OP_not:
@@ -899,6 +901,19 @@
return true;
}
+bool DIExpression::isImplicit() const {
+ unsigned N = getNumElements();
+ if (isValid() && N > 0) {
+ switch (getElement(N-1)) {
+ case dwarf::DW_OP_stack_value: return true;
+ case dwarf::DW_OP_LLVM_fragment:
+ return N > 1 && getElement(N-2) == dwarf::DW_OP_stack_value;
+ default: break;
+ }
+ }
+ return false;
+}
+
Optional<DIExpression::FragmentInfo>
DIExpression::getFragmentInfo(expr_op_iterator Start, expr_op_iterator End) {
for (auto I = Start; I != End; ++I)