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Always traverse GlobalVariable initializer when computing the export list

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Summary:
We are always importing the initializer for a GlobalVariable.
So if a GlobalVariable is in the export-list, we pull in any
refs as well.

Reviewers: tejohnson

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D19102

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267303 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Mehdi Amini 2016-04-23 23:29:24 +00:00
parent 1e7e2b2b55
commit aa73713b9a
3 changed files with 87 additions and 21 deletions
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71
lib/Transforms/IPO/FunctionImport.cpp
View File

@ -131,23 +131,54 @@ static const GlobalValueSummary *selectCallee(GlobalValue::GUID GUID,
return selectCallee(CalleeInfoList->second, Threshold);
}
/// Return true if the global \p GUID is exported by module \p ExportModulePath.
static bool isGlobalExported(const ModuleSummaryIndex &Index,
StringRef ExportModulePath,
GlobalValue::GUID GUID) {
auto CalleeInfoList = Index.findGlobalValueInfoList(GUID);
if (CalleeInfoList == Index.end())
// This global does not have a summary, it is not part of the ThinLTO
// process
return false;
auto DefinedInCalleeModule = llvm::find_if(
CalleeInfoList->second,
[&](const std::unique_ptr<GlobalValueInfo> &GlobInfo) {
auto *Summary = GlobInfo->summary();
assert(Summary && "Unexpected GlobalValueInfo without summary");
return Summary->modulePath() == ExportModulePath;
});
return (DefinedInCalleeModule != CalleeInfoList->second.end());
/// Mark the global \p GUID as export by module \p ExportModulePath if found in
/// this module. If it is a GlobalVariable, we also mark any referenced global
/// in the current module as exported.
static void exportGlobalInModule(const ModuleSummaryIndex &Index,
StringRef ExportModulePath,
GlobalValue::GUID GUID,
FunctionImporter::ExportSetTy &ExportList) {
auto FindGlobalInfoInModule =
[&](GlobalValue::GUID GUID) -> GlobalValueInfo *{
auto InfoList = Index.findGlobalValueInfoList(GUID);
if (InfoList == Index.end())
// This global does not have a summary, it is not part of the ThinLTO
// process
return nullptr;
auto Info = llvm::find_if(
InfoList->second,
[&](const std::unique_ptr<GlobalValueInfo> &GlobInfo) {
auto *Summary = GlobInfo->summary();
assert(Summary && "Unexpected GlobalValueInfo without summary");
return Summary->modulePath() == ExportModulePath;
});
if (Info == InfoList->second.end())
return nullptr;
return Info->get();
};
auto *GVInfo = FindGlobalInfoInModule(GUID);
if (!GVInfo)
return;
// We found it in the current module, mark as exported
ExportList.insert(GUID);
auto *Summary = GVInfo->summary();
auto GVS = dyn_cast<GlobalVarSummary>(Summary);
if (!GVS)
return;
// FunctionImportGlobalProcessing::doPromoteLocalToGlobal() will always
// trigger importing the initializer for `constant unnamed addr` globals that
// are referenced. We conservatively export all the referenced symbols for
// every global to workaround this, so that the ExportList is accurate.
// FIXME: with a "isConstant" flag in the summary we could be more targetted.
for (auto &Ref : GVS->refs()) {
auto GUID = Ref.getGUID();
auto *RefInfo = FindGlobalInfoInModule(GUID);
if (RefInfo)
// Found a ref in the current module, mark it as exported
ExportList.insert(GUID);
}
}
using EdgeInfo = std::pair<const FunctionSummary *, unsigned /* Threshold */>;
@ -211,13 +242,11 @@ static void computeImportForFunction(
// to the outside if they are defined in the same source module.
for (auto &Edge : ResolvedCalleeSummary->calls()) {
auto CalleeGUID = Edge.first.getGUID();
if (isGlobalExported(Index, ExportModulePath, CalleeGUID))
ExportList.insert(CalleeGUID);
exportGlobalInModule(Index, ExportModulePath, CalleeGUID, ExportList);
}
for (auto &Ref : ResolvedCalleeSummary->refs()) {
auto GUID = Ref.getGUID();
if (isGlobalExported(Index, ExportModulePath, GUID))
ExportList.insert(GUID);
exportGlobalInModule(Index, ExportModulePath, GUID, ExportList);
}
}

16
test/ThinLTO/X86/Inputs/referenced_by_constant.ll Normal file
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@ -0,0 +1,16 @@
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.11.0"
define void @referencedbyglobal() {
ret void
}
@someglobal = internal unnamed_addr constant i8* bitcast (void ()* @referencedbyglobal to i8*)
@ptr = global i8** null
define void @bar() #0 align 2 {
store i8** getelementptr inbounds (i8*, i8** @someglobal, i64 0) , i8*** @ptr, align 8
ret void
}

21
test/ThinLTO/X86/referenced_by_constant.ll Normal file
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@ -0,0 +1,21 @@
; Do setup work for all below tests: generate bitcode and combined index
; RUN: opt -module-summary %s -o %t.bc
; RUN: opt -module-summary %p/Inputs/referenced_by_constant.ll -o %t2.bc
; RUN: llvm-lto -thinlto-action=thinlink -o %t3.bc %t.bc %t2.bc
; Check the import side: we import bar() and @someglobal, but not @referencedbyglobal()
; RUN: llvm-lto -thinlto-action=import %t.bc -thinlto-index=%t3.bc -o - | llvm-dis -o - | FileCheck %s --check-prefix=IMPORT
; IMPORT: @someglobal.llvm.0 =
; IMPORT: define available_externally void @bar()
; IMPORT: declare void @referencedbyglobal()
target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.11.0"
declare void @bar()
define void @foo() {
call void @bar()
ret void
}