Update DW_OP_plus to DW_OP_plus_uconst

LLVM <= 4.0 used a non-standard interpretation of `DW_OP_plus`.  In the
DWARF standard, this adds two items on the expressions stack.  LLVM's
behavior was more like DWARF's `DW_OP_plus_uconst` -- adding a constant
that follows the op.  The patch series starting with [D33892] switched
to the standard DWARF interpretation, so we need to follow.

[D33892]: https://reviews.llvm.org/D33892

1 files changed, 8 insertions, 1 deletions

diff --git a/src/rustllvm/RustWrapper.cpp b/src/rustllvm/RustWrapper.cpp
index 95130d596e1..0fe533d447b 100644
--- a/src/rustllvm/RustWrapper.cpp
+++ b/src/rustllvm/RustWrapper.cpp
@@ -866,7 +866,14 @@ extern "C" int64_t LLVMRustDIBuilderCreateOpDeref() {
   return dwarf::DW_OP_deref;
 }
 
-extern "C" int64_t LLVMRustDIBuilderCreateOpPlus() { return dwarf::DW_OP_plus; }
+extern "C" int64_t LLVMRustDIBuilderCreateOpPlusUconst() {
+#if LLVM_VERSION_GE(5, 0)
+  return dwarf::DW_OP_plus_uconst;
+#else
+  // older LLVM used `plus` to behave like `plus_uconst`.
+  return dwarf::DW_OP_plus;
+#endif
+}
 
 extern "C" void LLVMRustWriteTypeToString(LLVMTypeRef Ty, RustStringRef Str) {
   RawRustStringOstream OS(Str);