[llvm] r267646 - ThinLTO: do not promote GlobalVariable that have a specific section.
Mehdi Amini via llvm-commits
llvm-commits at lists.llvm.org
Tue Apr 26 17:32:13 PDT 2016
Author: mehdi_amini
Date: Tue Apr 26 19:32:13 2016
New Revision: 267646
URL: http://llvm.org/viewvc/llvm-project?rev=267646&view=rev
Log:
ThinLTO: do not promote GlobalVariable that have a specific section.
Differential Revision: http://reviews.llvm.org/D18298
From: Mehdi Amini <mehdi.amini at apple.com>
Added:
llvm/trunk/test/ThinLTO/X86/Inputs/section.ll
llvm/trunk/test/ThinLTO/X86/section.ll
Modified:
llvm/trunk/include/llvm/IR/ModuleSummaryIndex.h
llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp
llvm/trunk/lib/Transforms/Utils/FunctionImportUtils.cpp
Modified: llvm/trunk/include/llvm/IR/ModuleSummaryIndex.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/IR/ModuleSummaryIndex.h?rev=267646&r1=267645&r2=267646&view=diff
==============================================================================
--- llvm/trunk/include/llvm/IR/ModuleSummaryIndex.h (original)
+++ llvm/trunk/include/llvm/IR/ModuleSummaryIndex.h Tue Apr 26 19:32:13 2016
@@ -168,6 +168,10 @@ public:
return static_cast<GlobalValue::LinkageTypes>(Flags.Linkage);
}
+ /// Return true if this summary is for a GlobalValue that needs promotion
+ /// to be referenced from another module.
+ bool needsRenaming() const { return GlobalValue::isLocalLinkage(linkage()); }
+
/// Return true if this global value is located in a specific section.
bool hasSection() const { return Flags.HasSection; }
Modified: llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp?rev=267646&r1=267645&r2=267646&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/FunctionImport.cpp Tue Apr 26 19:32:13 2016
@@ -75,6 +75,69 @@ static std::unique_ptr<Module> loadFile(
namespace {
+// Return true if the Summary describes a GlobalValue that can be externally
+// referenced, i.e. it does not need renaming (linkage is not local) or renaming
+// is possible (does not have a section for instance).
+static bool canBeExternallyReferenced(const GlobalValueSummary &Summary) {
+ if (!Summary.needsRenaming())
+ return true;
+
+ if (Summary.hasSection())
+ // Can't rename a global that needs renaming if has a section.
+ return false;
+
+ return true;
+}
+
+// Return true if \p GUID describes a GlobalValue that can be externally
+// referenced, i.e. it does not need renaming (linkage is not local) or
+// renaming is possible (does not have a section for instance).
+static bool canBeExternallyReferenced(const ModuleSummaryIndex &Index,
+ GlobalValue::GUID GUID) {
+ auto Summaries = Index.findGlobalValueSummaryList(GUID);
+ if (Summaries == Index.end())
+ return true;
+ if (Summaries->second.size() != 1)
+ // If there are multiple globals with this GUID, then we know it is
+ // not a local symbol, and it is necessarily externally referenced.
+ return true;
+
+ // We don't need to check for the module path, because if it can't be
+ // externally referenced and we call it, it is necessarilly in the same
+ // module
+ return canBeExternallyReferenced(**Summaries->second.begin());
+}
+
+// Return true if the global described by \p Summary can be imported in another
+// module.
+static bool eligibleForImport(const ModuleSummaryIndex &Index,
+ const GlobalValueSummary &Summary) {
+ if (!canBeExternallyReferenced(Summary))
+ // Can't import a global that needs renaming if has a section for instance.
+ // FIXME: we may be able to import it by copying it without promotion.
+ return false;
+
+ // Check references (and potential calls) in the same module. If the current
+ // value references a global that can't be externally referenced it is not
+ // eligible for import.
+ bool AllRefsCanBeExternallyReferenced =
+ llvm::all_of(Summary.refs(), [&](const ValueInfo &VI) {
+ return canBeExternallyReferenced(Index, VI.getGUID());
+ });
+ if (!AllRefsCanBeExternallyReferenced)
+ return false;
+
+ if (auto *FuncSummary = dyn_cast<FunctionSummary>(&Summary)) {
+ bool AllCallsCanBeExternallyReferenced = llvm::all_of(
+ FuncSummary->calls(), [&](const FunctionSummary::EdgeTy &Edge) {
+ return canBeExternallyReferenced(Index, Edge.first.getGUID());
+ });
+ if (!AllCallsCanBeExternallyReferenced)
+ return false;
+ }
+ return true;
+}
+
/// Given a list of possible callee implementation for a call site, select one
/// that fits the \p Threshold.
///
@@ -86,7 +149,8 @@ namespace {
/// - One that has PGO data attached.
/// - [insert you fancy metric here]
static const GlobalValueSummary *
-selectCallee(const GlobalValueSummaryList &CalleeSummaryList,
+selectCallee(const ModuleSummaryIndex &Index,
+ const GlobalValueSummaryList &CalleeSummaryList,
unsigned Threshold) {
auto It = llvm::find_if(
CalleeSummaryList,
@@ -111,6 +175,9 @@ selectCallee(const GlobalValueSummaryLis
if (Summary->instCount() > Threshold)
return false;
+ if (!eligibleForImport(Index, *Summary))
+ return false;
+
return true;
});
if (It == CalleeSummaryList.end())
@@ -125,10 +192,9 @@ static const GlobalValueSummary *selectC
unsigned Threshold,
const ModuleSummaryIndex &Index) {
auto CalleeSummaryList = Index.findGlobalValueSummaryList(GUID);
- if (CalleeSummaryList == Index.end()) {
+ if (CalleeSummaryList == Index.end())
return nullptr; // This function does not have a summary
- }
- return selectCallee(CalleeSummaryList->second, Threshold);
+ return selectCallee(Index, CalleeSummaryList->second, Threshold);
}
/// Mark the global \p GUID as export by module \p ExportModulePath if found in
Modified: llvm/trunk/lib/Transforms/Utils/FunctionImportUtils.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/FunctionImportUtils.cpp?rev=267646&r1=267645&r2=267646&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/FunctionImportUtils.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/FunctionImportUtils.cpp Tue Apr 26 19:32:13 2016
@@ -64,6 +64,11 @@ bool FunctionImportGlobalProcessing::doP
if (GVar && GVar->isConstant() && GVar->hasUnnamedAddr())
return false;
+ if (GVar && GVar->hasSection())
+ // Some sections like "__DATA,__cfstring" are "magic" and promotion is not
+ // allowed. Just disable promotion on any GVar with sections right now.
+ return false;
+
// Eventually we only need to promote functions in the exporting module that
// are referenced by a potentially exported function (i.e. one that is in the
// summary index).
Added: llvm/trunk/test/ThinLTO/X86/Inputs/section.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ThinLTO/X86/Inputs/section.ll?rev=267646&view=auto
==============================================================================
--- llvm/trunk/test/ThinLTO/X86/Inputs/section.ll (added)
+++ llvm/trunk/test/ThinLTO/X86/Inputs/section.ll Tue Apr 26 19:32:13 2016
@@ -0,0 +1,13 @@
+; An internal global variable that can't be renamed because it has a section
+ at var_with_section = internal global i32 0, section "some_section"
+
+; @reference_gv_with_section() can't be imported
+define i32 @reference_gv_with_section() {
+ %res = load i32, i32* @var_with_section
+ ret i32 %res
+}
+
+; canary
+define void @foo() {
+ ret void
+}
Added: llvm/trunk/test/ThinLTO/X86/section.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/ThinLTO/X86/section.ll?rev=267646&view=auto
==============================================================================
--- llvm/trunk/test/ThinLTO/X86/section.ll (added)
+++ llvm/trunk/test/ThinLTO/X86/section.ll Tue Apr 26 19:32:13 2016
@@ -0,0 +1,25 @@
+; 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/section.ll -o %t2.bc
+; RUN: llvm-lto -thinlto-action=thinlink -o %t3.bc %t.bc %t2.bc
+
+; Check that we don't promote 'var_with_section'
+; RUN: llvm-lto -thinlto-action=promote %t2.bc -thinlto-index=%t3.bc -o - | llvm-dis -o - | FileCheck %s --check-prefix=PROMOTE
+; PROMOTE: @var_with_section = internal global i32 0, section "some_section"
+
+; RUN: llvm-lto -thinlto-action=import %t.bc -thinlto-index=%t3.bc -o - | llvm-dis -o - | FileCheck %s --check-prefix=IMPORT
+; Check that section prevent import of @reference_gv_with_section.
+; IMPORT: declare void @reference_gv_with_section()
+; Canary to check that importing is correctly set up.
+; IMPORT: define available_externally void @foo()
+
+
+define i32 @main() {
+ call void @reference_gv_with_section()
+ call void @foo()
+ ret i32 42
+}
+
+
+declare void @reference_gv_with_section()
+declare void @foo()
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