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, 10 deletions

diff --git a/llvm/lib/IR/DebugInfo.cpp b/llvm/lib/IR/DebugInfo.cpp
index ca7a4f4801b..3e34572c044 100644
--- a/llvm/lib/IR/DebugInfo.cpp
+++ b/llvm/lib/IR/DebugInfo.cpp
@@ -35,16 +35,6 @@ using namespace llvm::dwarf;
 
 DIScopeRef DIScope::getRef() const { return MDScopeRef::get(get()); }
 
-DIVariable llvm::createInlinedVariable(MDNode *DV, MDNode *InlinedScope,
-                                       LLVMContext &VMContext) {
-  return cast<MDLocalVariable>(DV)
-      ->withInline(cast_or_null<MDLocation>(InlinedScope));
-}
-
-DIVariable llvm::cleanseInlinedVariable(MDNode *DV, LLVMContext &VMContext) {
-  return cast<MDLocalVariable>(DV)->withoutInline();
-}
-
 DISubprogram llvm::getDISubprogram(const MDNode *Scope) {
   if (auto *LocalScope = dyn_cast_or_null<MDLocalScope>(Scope))
     return LocalScope->getSubprogram();