DebugInfo: Remove 'inlinedAt:' field from MDLocalVariable

Remove 'inlinedAt:' from MDLocalVariable.  Besides saving some memory
(variables with it seem to be single largest `Metadata` contributer to
memory usage right now in -g -flto builds), this stops optimization and
backend passes from having to change local variables.

The 'inlinedAt:' field was used by the backend in two ways:

 1. To tell the backend whether and into what a variable was inlined.
 2. To create a unique id for each inlined variable.

Instead, rely on the 'inlinedAt:' field of the intrinsic's `!dbg`
attachment, and change the DWARF backend to use a typedef called
`InlinedVariable` which is `std::pair<MDLocalVariable*, MDLocation*>`.
This `DebugLoc` is already passed reliably through the backend (as
verified by r234021).

This commit removes the check from r234021, but I added a new check
(that will survive) in r235048, and changed the `DIBuilder` API in
r235041 to require a `!dbg` attachment whose 'scope:` is in the same
`MDSubprogram` as the variable's.

If this breaks your out-of-tree testcases, perhaps the script I used
(mdlocalvariable-drop-inlinedat.sh) will help; I'll attach it to PR22778
in a moment.

llvm-svn: 235050

1 files changed, 0 insertions, 13 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 7683b6bacf1..a08ffbeb329 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -904,19 +904,6 @@ static void fixupLineNumbers(Function *Fn, Function::iterator FI,
         BI->setDebugLoc(TheCallDL);
       } else {
         BI->setDebugLoc(updateInlinedAtInfo(DL, InlinedAtNode, BI->getContext(), IANodes));
-        if (DbgValueInst *DVI = dyn_cast<DbgValueInst>(BI)) {
-          LLVMContext &Ctx = BI->getContext();
-          MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt();
-          DVI->setOperand(2, MetadataAsValue::get(
-                                 Ctx, createInlinedVariable(DVI->getVariable(),
-                                                            InlinedAt, Ctx)));
-        } else if (DbgDeclareInst *DDI = dyn_cast<DbgDeclareInst>(BI)) {
-          LLVMContext &Ctx = BI->getContext();
-          MDNode *InlinedAt = BI->getDebugLoc().getInlinedAt();
-          DDI->setOperand(1, MetadataAsValue::get(
-                                 Ctx, createInlinedVariable(DDI->getVariable(),
-                                                            InlinedAt, Ctx)));
-        }
       }
     }
   }