From 816047d44c6cf672981d85e16c22bf610508f09b Mon Sep 17 00:00:00 2001 From: Reid Kleckner Date: Thu, 18 May 2017 17:24:10 +0000 Subject: [IR] De-virtualize ~Value to save a vptr Summary: Implements PR889 Removing the virtual table pointer from Value saves 1% of RSS when doing LTO of llc on Linux. The impact on time was positive, but too noisy to conclusively say that performance improved. Here is a link to the spreadsheet with the original data: https://docs.google.com/spreadsheets/d/1F4FHir0qYnV0MEp2sYYp_BuvnJgWlWPhWOwZ6LbW7W4/edit?usp=sharing This change makes it invalid to directly delete a Value, User, or Instruction pointer. Instead, such code can be rewritten to a null check and a call Value::deleteValue(). Value objects tend to have their lifetimes managed through iplist, so for the most part, this isn't a big deal. However, there are some places where LLVM deletes values, and those places had to be migrated to deleteValue. I have also created llvm::unique_value, which has a custom deleter, so it can be used in place of std::unique_ptr. I had to add the "DerivedUser" Deleter escape hatch for MemorySSA, which derives from User outside of lib/IR. Code in IR cannot include MemorySSA headers or call the MemoryAccess object destructors without introducing a circular dependency, so we need some level of indirection. Unfortunately, no class derived from User may have any virtual methods, because adding a virtual method would break User::getHungOffOperands(), which assumes that it can find the use list immediately prior to the User object. I've added a static_assert to the appropriate OperandTraits templates to help people avoid this trap. Reviewers: chandlerc, mehdi_amini, pete, dberlin, george.burgess.iv Reviewed By: chandlerc Subscribers: krytarowski, eraman, george.burgess.iv, mzolotukhin, Prazek, nlewycky, hans, inglorion, pcc, tejohnson, dberlin, llvm-commits Differential Revision: https://reviews.llvm.org/D31261 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303362 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/IR/ConstantsContext.h | 20 -------------------- 1 file changed, 20 deletions(-) (limited to 'lib/IR/ConstantsContext.h') diff --git a/lib/IR/ConstantsContext.h b/lib/IR/ConstantsContext.h index 25eb9452d9d..6c189cf656d 100644 --- a/lib/IR/ConstantsContext.h +++ b/lib/IR/ConstantsContext.h @@ -44,8 +44,6 @@ namespace llvm { /// UnaryConstantExpr - This class is private to Constants.cpp, and is used /// behind the scenes to implement unary constant exprs. class UnaryConstantExpr : public ConstantExpr { - void anchor() override; - public: UnaryConstantExpr(unsigned Opcode, Constant *C, Type *Ty) : ConstantExpr(Ty, Opcode, &Op<0>(), 1) { @@ -65,8 +63,6 @@ public: /// BinaryConstantExpr - This class is private to Constants.cpp, and is used /// behind the scenes to implement binary constant exprs. class BinaryConstantExpr : public ConstantExpr { - void anchor() override; - public: BinaryConstantExpr(unsigned Opcode, Constant *C1, Constant *C2, unsigned Flags) @@ -90,8 +86,6 @@ public: /// SelectConstantExpr - This class is private to Constants.cpp, and is used /// behind the scenes to implement select constant exprs. class SelectConstantExpr : public ConstantExpr { - void anchor() override; - public: SelectConstantExpr(Constant *C1, Constant *C2, Constant *C3) : ConstantExpr(C2->getType(), Instruction::Select, &Op<0>(), 3) { @@ -115,8 +109,6 @@ public: /// Constants.cpp, and is used behind the scenes to implement /// extractelement constant exprs. class ExtractElementConstantExpr : public ConstantExpr { - void anchor() override; - public: ExtractElementConstantExpr(Constant *C1, Constant *C2) : ConstantExpr(cast(C1->getType())->getElementType(), @@ -140,8 +132,6 @@ public: /// Constants.cpp, and is used behind the scenes to implement /// insertelement constant exprs. class InsertElementConstantExpr : public ConstantExpr { - void anchor() override; - public: InsertElementConstantExpr(Constant *C1, Constant *C2, Constant *C3) : ConstantExpr(C1->getType(), Instruction::InsertElement, @@ -166,8 +156,6 @@ public: /// Constants.cpp, and is used behind the scenes to implement /// shufflevector constant exprs. class ShuffleVectorConstantExpr : public ConstantExpr { - void anchor() override; - public: ShuffleVectorConstantExpr(Constant *C1, Constant *C2, Constant *C3) : ConstantExpr(VectorType::get( @@ -195,8 +183,6 @@ public: /// Constants.cpp, and is used behind the scenes to implement /// extractvalue constant exprs. class ExtractValueConstantExpr : public ConstantExpr { - void anchor() override; - public: ExtractValueConstantExpr(Constant *Agg, ArrayRef IdxList, Type *DestTy) @@ -230,8 +216,6 @@ public: /// Constants.cpp, and is used behind the scenes to implement /// insertvalue constant exprs. class InsertValueConstantExpr : public ConstantExpr { - void anchor() override; - public: InsertValueConstantExpr(Constant *Agg, Constant *Val, ArrayRef IdxList, Type *DestTy) @@ -271,8 +255,6 @@ class GetElementPtrConstantExpr : public ConstantExpr { GetElementPtrConstantExpr(Type *SrcElementTy, Constant *C, ArrayRef IdxList, Type *DestTy); - void anchor() override; - public: static GetElementPtrConstantExpr *Create(Type *SrcElementTy, Constant *C, ArrayRef IdxList, @@ -301,8 +283,6 @@ public: // behind the scenes to implement ICmp and FCmp constant expressions. This is // needed in order to store the predicate value for these instructions. class CompareConstantExpr : public ConstantExpr { - void anchor() override; - public: unsigned short predicate; CompareConstantExpr(Type *ty, Instruction::OtherOps opc, -- cgit v1.2.3