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, 2 insertions, 4 deletions

diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
index 1eead4ad41d..b6a6254ba6a 100644
--- a/llvm/lib/IR/LLVMContextImpl.h
+++ b/llvm/lib/IR/LLVMContextImpl.h
@@ -289,11 +289,9 @@ public:
 
   DenseMap<std::pair<const Function *, const BasicBlock *>, BlockAddress *>
     BlockAddresses;
-  ConstantUniqueMap<ExprMapKeyType, const ExprMapKeyType&, Type, ConstantExpr>
-    ExprConstants;
+  ConstantUniqueMap<ConstantExpr> ExprConstants;
 
-  ConstantUniqueMap<InlineAsmKeyType, const InlineAsmKeyType&, PointerType,
-                    InlineAsm> InlineAsms;
+  ConstantUniqueMap<InlineAsm> InlineAsms;
   
   ConstantInt *TheTrueVal;
   ConstantInt *TheFalseVal;