From dda73336ad22bd0b5ecda17040c50fb10fcbe5fb Mon Sep 17 00:00:00 2001 From: Mingming Liu Date: Wed, 10 Apr 2024 19:46:01 -0700 Subject: [ThinLTO]Record import type in GlobalValueSummary::GVFlags (#87597) The motivating use case is to support import the function declaration across modules to construct call graph edges for indirect calls [1] when importing the function definition costs too much compile time (e.g., the function is too large has no `noinline` attribute). 1. Currently, when the compiled IR module doesn't have a function definition but its postlink combined summary contains the function summary or a global alias summary with this function as aliasee, the function definition will be imported from source module by IRMover. The implementation is in FunctionImporter::importFunctions [2] 2. In order for FunctionImporter to import a declaration of a function, both function summary and alias summary need to carry the def / decl state. Specifically, all existing summary fields doesn't differ across import modules, but the def / decl state of is decided by ``. This change encodes the def/decl state in `GlobalValueSummary::GVFlags`. In the subsequent changes 1. The indexing step `computeImportForModule` [3] will compute the set of definitions and the set of declarations for each module, and passing on the information to bitcode writer. 2. Bitcode writer will look up the def/decl state and sets the state when it writes out the flag value. This is demonstrated in https://github.com/llvm/llvm-project/pull/87600 3. Function importer will read the def/decl state when reading the combined summary to figure out two sets of global values, and IRMover will be updated to import the declaration (aka linkGlobalValuePrototype [4]) into the destination module. - The next change is https://github.com/llvm/llvm-project/pull/87600 [1] mentioned in rfc https://discourse.llvm.org/t/rfc-for-better-call-graph-sort-build-a-more-complete-call-graph-by-adding-more-indirect-call-edges/74029#support-cross-module-function-declaration-import-5 [2] https://github.com/llvm/llvm-project/blob/3b337242ee165554f0017b00671381ec5b1ba855/llvm/lib/Transforms/IPO/FunctionImport.cpp#L1608-L1764 [3] https://github.com/llvm/llvm-project/blob/3b337242ee165554f0017b00671381ec5b1ba855/llvm/lib/Transforms/IPO/FunctionImport.cpp#L856 [4] https://github.com/llvm/llvm-project/blob/3b337242ee165554f0017b00671381ec5b1ba855/llvm/lib/Linker/IRMover.cpp#L605 --- llvm/lib/AsmParser/LLParser.cpp | 33 ++++++++++++++++++++++++++++++--- 1 file changed, 30 insertions(+), 3 deletions(-) (limited to 'llvm/lib/AsmParser/LLParser.cpp') diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp index f546e05..6310412 100644 --- a/llvm/lib/AsmParser/LLParser.cpp +++ b/llvm/lib/AsmParser/LLParser.cpp @@ -2083,6 +2083,20 @@ void LLParser::parseOptionalVisibility(unsigned &Res) { Lex.Lex(); } +bool LLParser::parseOptionalImportType(lltok::Kind Kind, + GlobalValueSummary::ImportKind &Res) { + switch (Kind) { + default: + return tokError("unknown import kind. Expect definition or declaration."); + case lltok::kw_definition: + Res = GlobalValueSummary::Definition; + return false; + case lltok::kw_declaration: + Res = GlobalValueSummary::Declaration; + return false; + } +} + /// parseOptionalDLLStorageClass /// ::= /*empty*/ /// ::= 'dllimport' @@ -9230,7 +9244,8 @@ bool LLParser::parseFunctionSummary(std::string Name, GlobalValue::GUID GUID, GlobalValueSummary::GVFlags GVFlags = GlobalValueSummary::GVFlags( GlobalValue::ExternalLinkage, GlobalValue::DefaultVisibility, /*NotEligibleToImport=*/false, - /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false); + /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false, + GlobalValueSummary::Definition); unsigned InstCount; std::vector Calls; FunctionSummary::TypeIdInfo TypeIdInfo; @@ -9317,7 +9332,8 @@ bool LLParser::parseVariableSummary(std::string Name, GlobalValue::GUID GUID, GlobalValueSummary::GVFlags GVFlags = GlobalValueSummary::GVFlags( GlobalValue::ExternalLinkage, GlobalValue::DefaultVisibility, /*NotEligibleToImport=*/false, - /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false); + /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false, + GlobalValueSummary::Definition); GlobalVarSummary::GVarFlags GVarFlags(/*ReadOnly*/ false, /* WriteOnly */ false, /* Constant */ false, @@ -9375,7 +9391,8 @@ bool LLParser::parseAliasSummary(std::string Name, GlobalValue::GUID GUID, GlobalValueSummary::GVFlags GVFlags = GlobalValueSummary::GVFlags( GlobalValue::ExternalLinkage, GlobalValue::DefaultVisibility, /*NotEligibleToImport=*/false, - /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false); + /*Live=*/false, /*IsLocal=*/false, /*CanAutoHide=*/false, + GlobalValueSummary::Definition); if (parseToken(lltok::colon, "expected ':' here") || parseToken(lltok::lparen, "expected '(' here") || parseModuleReference(ModulePath) || @@ -10161,6 +10178,16 @@ bool LLParser::parseGVFlags(GlobalValueSummary::GVFlags &GVFlags) { return true; GVFlags.CanAutoHide = Flag; break; + case lltok::kw_importType: + Lex.Lex(); + if (parseToken(lltok::colon, "expected ':'")) + return true; + GlobalValueSummary::ImportKind IK; + if (parseOptionalImportType(Lex.getKind(), IK)) + return true; + GVFlags.ImportType = static_cast(IK); + Lex.Lex(); + break; default: return error(Lex.getLoc(), "expected gv flag type"); } -- cgit v1.1