[Debugify] Handle failure to get fragment size when checking dbg.values

It's not possible to get the fragment size of some dbg.values. Teach the
mis-sized dbg.value diagnostic to detect this scenario and bail out.

Tested with:
$ find test/Transforms -print -exec opt -debugify-each -instcombine {} \;

llvm-svn: 335695

1 files changed, 7 insertions, 4 deletions

diff --git a/llvm/tools/opt/Debugify.cpp b/llvm/tools/opt/Debugify.cpp
index 54ff00849b0..e8437016d94 100644
--- a/llvm/tools/opt/Debugify.cpp
+++ b/llvm/tools/opt/Debugify.cpp
@@ -184,12 +184,15 @@ bool diagnoseMisSizedDbgValue(Module &M, DbgValueInst *DVI) {
 
   Type *Ty = V->getType();
   uint64_t ValueOperandSize = getAllocSizeInBits(M, Ty);
-  uint64_t DbgVarSize = *DVI->getFragmentSizeInBits();
-  bool HasBadSize = Ty->isIntegerTy() ? (ValueOperandSize < DbgVarSize)
-                                      : (ValueOperandSize != DbgVarSize);
+  Optional<uint64_t> DbgVarSize = DVI->getFragmentSizeInBits();
+  if (!ValueOperandSize || !DbgVarSize)
+    return false;
+
+  bool HasBadSize = Ty->isIntegerTy() ? (ValueOperandSize < *DbgVarSize)
+                                      : (ValueOperandSize != *DbgVarSize);
   if (HasBadSize) {
     dbg() << "ERROR: dbg.value operand has size " << ValueOperandSize
-          << ", but its variable has size " << DbgVarSize << ": ";
+          << ", but its variable has size " << *DbgVarSize << ": ";
     DVI->print(dbg());
     dbg() << "\n";
   }