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/Analysis/ModuleSummaryAnalysis.cpp | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) (limited to 'llvm/lib/Analysis/ModuleSummaryAnalysis.cpp') diff --git a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp index 3ad0bab..deda1ee 100644 --- a/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp +++ b/llvm/lib/Analysis/ModuleSummaryAnalysis.cpp @@ -635,7 +635,8 @@ static void computeFunctionSummary( HasIndirBranchToBlockAddress || HasIFuncCall; GlobalValueSummary::GVFlags Flags( F.getLinkage(), F.getVisibility(), NotEligibleForImport, - /* Live = */ false, F.isDSOLocal(), F.canBeOmittedFromSymbolTable()); + /* Live = */ false, F.isDSOLocal(), F.canBeOmittedFromSymbolTable(), + GlobalValueSummary::ImportKind::Definition); FunctionSummary::FFlags FunFlags{ F.doesNotAccessMemory(), F.onlyReadsMemory() && !F.doesNotAccessMemory(), F.hasFnAttribute(Attribute::NoRecurse), F.returnDoesNotAlias(), @@ -761,7 +762,8 @@ static void computeVariableSummary(ModuleSummaryIndex &Index, bool NonRenamableLocal = isNonRenamableLocal(V); GlobalValueSummary::GVFlags Flags( V.getLinkage(), V.getVisibility(), NonRenamableLocal, - /* Live = */ false, V.isDSOLocal(), V.canBeOmittedFromSymbolTable()); + /* Live = */ false, V.isDSOLocal(), V.canBeOmittedFromSymbolTable(), + GlobalValueSummary::Definition); VTableFuncList VTableFuncs; // If splitting is not enabled, then we compute the summary information @@ -807,7 +809,8 @@ static void computeAliasSummary(ModuleSummaryIndex &Index, const GlobalAlias &A, bool NonRenamableLocal = isNonRenamableLocal(A); GlobalValueSummary::GVFlags Flags( A.getLinkage(), A.getVisibility(), NonRenamableLocal, - /* Live = */ false, A.isDSOLocal(), A.canBeOmittedFromSymbolTable()); + /* Live = */ false, A.isDSOLocal(), A.canBeOmittedFromSymbolTable(), + GlobalValueSummary::Definition); auto AS = std::make_unique(Flags); auto AliaseeVI = Index.getValueInfo(Aliasee->getGUID()); assert(AliaseeVI && "Alias expects aliasee summary to be available"); @@ -887,7 +890,8 @@ ModuleSummaryIndex llvm::buildModuleSummaryIndex( GlobalValue::InternalLinkage, GlobalValue::DefaultVisibility, /* NotEligibleToImport = */ true, /* Live = */ true, - /* Local */ GV->isDSOLocal(), GV->canBeOmittedFromSymbolTable()); + /* Local */ GV->isDSOLocal(), GV->canBeOmittedFromSymbolTable(), + GlobalValueSummary::Definition); CantBePromoted.insert(GV->getGUID()); // Create the appropriate summary type. if (Function *F = dyn_cast(GV)) { -- cgit v1.1