AsmPrinter: Change DIEValue to be stored by value

Change `DIEValue` to be stored/passed/etc. by value, instead of
reference.  It's now a discriminated union, with a `Val` field storing
the actual type.  The classes that used to inherit from `DIEValue` no
longer do.  There are two categories of these:

  - Small values fit in a single pointer and are stored by value.
  - Large values require auxiliary storage, and are stored by reference.

The only non-mechanical change is to tools/dsymutil/DwarfLinker.cpp.  It
was relying on `DIEInteger`s being passed around by reference, so I
replaced that assumption with a `PatchLocation` type that stores a safe
reference to where the `DIEInteger` lives instead.

This commit causes a temporary regression in memory usage, since I've
left merging `DIEAbbrevData` into `DIEValue` for a follow-up commit.  I
measured an increase from 845 MB to 879 MB, around 3.9%.  The follow-up
drops it lower than the starting point, and I've only recently brought
the memory this low anyway, so I'm committing these changes separately
to keep them incremental.  (I also considered swapping the commits, but
the other one first would cause a lot more code churn.)

(I'm looking at `llc` memory usage on `verify-uselistorder.lto.opt.bc`;
see r236629 for details.)

llvm-svn: 238349

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
index 10b58d4e86a..9951c1d116d 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfFile.cpp
@@ -94,13 +94,13 @@ unsigned DwarfFile::computeSizeAndOffset(DIE &Die, unsigned Offset) {
   // Start the size with the size of abbreviation code.
   Offset += getULEB128Size(Die.getAbbrevNumber());
 
-  const SmallVectorImpl<DIEValue *> &Values = Die.getValues();
+  const SmallVectorImpl<DIEValue> &Values = Die.getValues();
   const SmallVectorImpl<DIEAbbrevData> &AbbrevData = Abbrev.getData();
 
   // Size the DIE attribute values.
   for (unsigned i = 0, N = Values.size(); i < N; ++i)
     // Size attribute value.
-    Offset += Values[i]->SizeOf(Asm, AbbrevData[i].getForm());
+    Offset += Values[i].SizeOf(Asm, AbbrevData[i].getForm());
 
   // Get the children.
   const auto &Children = Die.getChildren();