IR: Rewrite ConstantUniqueMap

Rewrite `ConstantUniqueMap` to be more similar to
`ConstantAggrUniqueMap`.

  - Use a `DenseMap` with custom MapInfo instead of a `std::map` with
    linear lookups and deletion.
  - Don't waste memory explicitly storing (heavyweight) keys.

Only `ConstantExpr` and `InlineAsm` actually use this data structure, so
I also updated them to use it.

This code cleanup is a precursor to reducing RAUW traffic on
`ConstantExpr` -- I felt badly adding a new (linear) call to
`ConstantUniqueMap::FindExistingKey`, so this designs away the concern.

A follow-up commit will transition the users of `ConstantAggrUniqueMap`
over.

llvm-svn: 215957

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.cpp b/llvm/lib/IR/LLVMContextImpl.cpp
index 4c2791f0a8d..6513965ae7a 100644
--- a/llvm/lib/IR/LLVMContextImpl.cpp
+++ b/llvm/lib/IR/LLVMContextImpl.cpp
@@ -75,7 +75,7 @@ LLVMContextImpl::~LLVMContextImpl() {
   // Free the constants.  This is important to do here to ensure that they are
   // freed before the LeakDetector is torn down.
   std::for_each(ExprConstants.map_begin(), ExprConstants.map_end(),
-                DropReferences());
+                DropFirst());
   std::for_each(ArrayConstants.map_begin(), ArrayConstants.map_end(),
                 DropFirst());
   std::for_each(StructConstants.map_begin(), StructConstants.map_end(),