From 3efe00206f0f470bf322321efcb915b54f18118c Mon Sep 17 00:00:00 2001 From: Erich Keane Date: Fri, 20 Jul 2018 14:13:28 +0000 Subject: Implement cpu_dispatch/cpu_specific Multiversioning As documented here: https://software.intel.com/en-us/node/682969 and https://software.intel.com/en-us/node/523346. cpu_dispatch multiversioning is an ICC feature that provides for function multiversioning. This feature is implemented with two attributes: First, cpu_specific, which specifies the individual function versions. Second, cpu_dispatch, which specifies the location of the resolver function and the list of resolvable functions. This is valuable since it provides a mechanism where the resolver's TU can be specified in one location, and the individual implementions each in their own translation units. The goal of this patch is to be source-compatible with ICC, so this implementation diverges from the ICC implementation in a few ways: 1- Linux x86/64 only: This implementation uses ifuncs in order to properly dispatch functions. This is is a valuable performance benefit over the ICC implementation. A future patch will be provided to enable this feature on Windows, but it will obviously more closely fit ICC's implementation. 2- CPU Identification functions: ICC uses a set of custom functions to identify the feature list of the host processor. This patch uses the cpu_supports functionality in order to better align with 'target' multiversioning. 1- cpu_dispatch function def/decl: ICC's cpu_dispatch requires that the function marked cpu_dispatch be an empty definition. This patch supports that as well, however declarations are also permitted, since the linker will solve the issue of multiple emissions. Differential Revision: https://reviews.llvm.org/D47474 llvm-svn: 337552 --- clang/lib/CodeGen/CodeGenModule.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'clang/lib/CodeGen/CodeGenModule.h') diff --git a/clang/lib/CodeGen/CodeGenModule.h b/clang/lib/CodeGen/CodeGenModule.h index d2c7b327f98..ee64ed4f2ae 100644 --- a/clang/lib/CodeGen/CodeGenModule.h +++ b/clang/lib/CodeGen/CodeGenModule.h @@ -366,6 +366,13 @@ private: llvm::MapVector MangledDeclNames; llvm::StringMap Manglings; + // An ordered map of canonical GlobalDecls paired with the cpu-index for + // cpu-specific name manglings. + llvm::MapVector, StringRef> + CPUSpecificMangledDeclNames; + llvm::StringMap, llvm::BumpPtrAllocator> + CPUSpecificManglings; + /// Global annotations. std::vector Annotations; @@ -1283,7 +1290,6 @@ private: llvm::Constant *GetOrCreateMultiVersionIFunc(GlobalDecl GD, llvm::Type *DeclTy, - StringRef MangledName, const FunctionDecl *FD); void UpdateMultiVersionNames(GlobalDecl GD, const FunctionDecl *FD); @@ -1307,6 +1313,7 @@ private: void EmitGlobalVarDefinition(const VarDecl *D, bool IsTentative = false); void EmitAliasDefinition(GlobalDecl GD); void emitIFuncDefinition(GlobalDecl GD); + void emitCPUDispatchDefinition(GlobalDecl GD); void EmitObjCPropertyImplementations(const ObjCImplementationDecl *D); void EmitObjCIvarInitializations(ObjCImplementationDecl *D); -- cgit v1.2.3