[PATCH] D144745: [LLVMContextImpl] Separate out integer constant zeroes

[Arthur Eubanks via Phabricator via llvm-commits]

aeubanks created this revision.
aeubanks added reviewers: asbirlea, nikic.
Herald added subscribers: StephenFan, hiraditya.
Herald added a project: All.
aeubanks requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Very small compile time improvement:
https://llvm-compile-time-tracker.com/compare.php?from=a628ca4925f7249b4fbd3e932c9627b12e2770dd&to=6a7a8907e8334eaf551742148079c628f78e6ed7&stat=instructions:u


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D144745

Files:
  llvm/lib/IR/Constants.cpp
  llvm/lib/IR/LLVMContextImpl.cpp
  llvm/lib/IR/LLVMContextImpl.h


Index: llvm/lib/IR/LLVMContextImpl.h
===================================================================
--- llvm/lib/IR/LLVMContextImpl.h
+++ llvm/lib/IR/LLVMContextImpl.h
@@ -1446,13 +1446,12 @@
 
   DenseMap<const Value *, ValueName *> ValueNames;
 
-  using IntMapTy =
-      DenseMap<APInt, std::unique_ptr<ConstantInt>, DenseMapAPIntKeyInfo>;
-  IntMapTy IntConstants;
+  DenseMap<unsigned, std::unique_ptr<ConstantInt>> IntZeroConstants;
+  DenseMap<APInt, std::unique_ptr<ConstantInt>, DenseMapAPIntKeyInfo>
+      IntConstants;
 
-  using FPMapTy =
-      DenseMap<APFloat, std::unique_ptr<ConstantFP>, DenseMapAPFloatKeyInfo>;
-  FPMapTy FPConstants;
+  DenseMap<APFloat, std::unique_ptr<ConstantFP>, DenseMapAPFloatKeyInfo>
+      FPConstants;
 
   FoldingSet<AttributeImpl> AttrsSet;
   FoldingSet<AttributeListImpl> AttrsLists;
Index: llvm/lib/IR/LLVMContextImpl.cpp
===================================================================
--- llvm/lib/IR/LLVMContextImpl.cpp
+++ llvm/lib/IR/LLVMContextImpl.cpp
@@ -116,6 +116,7 @@
   CTNConstants.clear();
   UVConstants.clear();
   PVConstants.clear();
+  IntZeroConstants.clear();
   IntConstants.clear();
   FPConstants.clear();
   CDSConstants.clear();
Index: llvm/lib/IR/Constants.cpp
===================================================================
--- llvm/lib/IR/Constants.cpp
+++ llvm/lib/IR/Constants.cpp
@@ -874,7 +874,9 @@
 ConstantInt *ConstantInt::get(LLVMContext &Context, const APInt &V) {
   // get an existing value or the insertion position
   LLVMContextImpl *pImpl = Context.pImpl;
-  std::unique_ptr<ConstantInt> &Slot = pImpl->IntConstants[V];
+  std::unique_ptr<ConstantInt> &Slot =
+      V.isZero() ? pImpl->IntZeroConstants[V.getBitWidth()]
+                 : pImpl->IntConstants[V];
   if (!Slot) {
     // Get the corresponding integer type for the bit width of the value.
     IntegerType *ITy = IntegerType::get(Context, V.getBitWidth());


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