[DebugInfo] Allow non-stack_value variadic expressions and use in DBG_INSTR_REF

Prior to this patch, variadic DIExpressions (i.e. ones that contain
DW_OP_LLVM_arg) could only be created by salvaging debug values to create
stack value expressions, resulting in a DBG_VALUE_LIST being created. As of
the previous patch in this patch stack, DBG_INSTR_REF's syntax has been
changed to match DBG_VALUE_LIST in preparation for supporting variadic
expressions. This patch adds some minor changes needed to allow variadic
expressions that aren't stack values to exist, and allows variadic expressions
that are trivially reduceable to non-variadic expressions to be handled
similarly to non-variadic expressions.

Reviewed by: jmorse

Differential Revision: https://reviews.llvm.org/D133926

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/MachineFunction.cpp b/llvm/lib/CodeGen/MachineFunction.cpp
index fad5981..9625099 100644
--- a/llvm/lib/CodeGen/MachineFunction.cpp
+++ b/llvm/lib/CodeGen/MachineFunction.cpp
@@ -44,6 +44,7 @@
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Constant.h"
 #include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DebugInfoMetadata.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
@@ -1153,6 +1154,10 @@ void MachineFunction::finalizeDebugInstrRefs() {
         MakeUndefDbgValue(MI);
         continue;
       }
+      // Only convert Expr to variadic form when we're sure we're emitting a
+      // complete instruction reference.
+      MI.getDebugExpressionOp().setMetadata(
+          DIExpression::convertToVariadicExpression(MI.getDebugExpression()));
 
       assert(Reg.isVirtual());
       MachineInstr &DefMI = *RegInfo->def_instr_begin(Reg);