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[Linker] Provide callback for internalization

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Differential Revision: https://reviews.llvm.org/D30738

llvm-svn: 297649
This commit is contained in:
Jonas Devlieghere 2017-03-13 18:08:11 +00:00
parent d35723bd11
commit 9840ae61ae
5 changed files with 69 additions and 25 deletions
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14
include/llvm/Linker/Linker.h
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@ -10,6 +10,7 @@
#ifndef LLVM_LINKER_LINKER_H
#define LLVM_LINKER_LINKER_H
#include "llvm/ADT/StringSet.h"
#include "llvm/Linker/IRMover.h"
namespace llvm {
@ -29,7 +30,6 @@ public:
None = 0,
OverrideFromSrc = (1 << 0),
LinkOnlyNeeded = (1 << 1),
InternalizeLinkedSymbols = (1 << 2),
};
Linker(Module &M);
@ -39,11 +39,19 @@ public:
/// Passing OverrideSymbols as true will have symbols from Src
/// shadow those in the Dest.
///
/// Passing InternalizeCallback will have the linker call the function with
/// the new module and a list of global value names to be internalized by the
/// callback.
///
/// Returns true on error.
bool linkInModule(std::unique_ptr<Module> Src, unsigned Flags = Flags::None);
bool linkInModule(std::unique_ptr<Module> Src, unsigned Flags = Flags::None,
std::function<void(Module &, const StringSet<> &)>
InternalizeCallback = {});
static bool linkModules(Module &Dest, std::unique_ptr<Module> Src,
unsigned Flags = Flags::None);
unsigned Flags = Flags::None,
std::function<void(Module &, const StringSet<> &)>
InternalizeCallback = {});
};
} // End llvm namespace

46
lib/Linker/LinkModules.cpp
View File

@ -14,7 +14,6 @@
#include "LinkDiagnosticInfo.h"
#include "llvm-c/Linker.h"
#include "llvm/ADT/SetVector.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/IR/Comdat.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/GlobalValue.h"
@ -33,11 +32,18 @@ class ModuleLinker {
std::unique_ptr<Module> SrcM;
SetVector<GlobalValue *> ValuesToLink;
StringSet<> Internalize;
/// For symbol clashes, prefer those from Src.
unsigned Flags;
/// List of global value names that should be internalized.
StringSet<> Internalize;
/// Function that will perform the actual internalization. The reason for a
/// callback is that the linker cannot call internalizeModule without
/// creating a circular dependency between IPO and the linker.
std::function<void(Module &, const StringSet<> &)> InternalizeCallback;
/// Used as the callback for lazy linking.
/// The mover has just hit GV and we have to decide if it, and other members
/// of the same comdat, should be linked. Every member to be linked is passed
@ -46,9 +52,6 @@ class ModuleLinker {
bool shouldOverrideFromSrc() { return Flags & Linker::OverrideFromSrc; }
bool shouldLinkOnlyNeeded() { return Flags & Linker::LinkOnlyNeeded; }
bool shouldInternalizeLinkedSymbols() {
return Flags & Linker::InternalizeLinkedSymbols;
}
bool shouldLinkFromSource(bool &LinkFromSrc, const GlobalValue &Dest,
const GlobalValue &Src);
@ -104,8 +107,11 @@ class ModuleLinker {
bool linkIfNeeded(GlobalValue &GV);
public:
ModuleLinker(IRMover &Mover, std::unique_ptr<Module> SrcM, unsigned Flags)
: Mover(Mover), SrcM(std::move(SrcM)), Flags(Flags) {}
ModuleLinker(IRMover &Mover, std::unique_ptr<Module> SrcM, unsigned Flags,
std::function<void(Module &, const StringSet<> &)>
InternalizeCallback = {})
: Mover(Mover), SrcM(std::move(SrcM)), Flags(Flags),
InternalizeCallback(std::move(InternalizeCallback)) {}
bool run();
};
@ -383,7 +389,7 @@ void ModuleLinker::addLazyFor(GlobalValue &GV, const IRMover::ValueAdder &Add) {
!shouldLinkOnlyNeeded())
return;
if (shouldInternalizeLinkedSymbols())
if (InternalizeCallback)
Internalize.insert(GV.getName());
Add(GV);
@ -397,7 +403,7 @@ void ModuleLinker::addLazyFor(GlobalValue &GV, const IRMover::ValueAdder &Add) {
return;
if (!LinkFromSrc)
continue;
if (shouldInternalizeLinkedSymbols())
if (InternalizeCallback)
Internalize.insert(GV2->getName());
Add(*GV2);
}
@ -526,7 +532,7 @@ bool ModuleLinker::run() {
}
}
if (shouldInternalizeLinkedSymbols()) {
if (InternalizeCallback) {
for (GlobalValue *GV : ValuesToLink)
Internalize.insert(GV->getName());
}
@ -547,18 +553,19 @@ bool ModuleLinker::run() {
if (HasErrors)
return true;
for (auto &P : Internalize) {
GlobalValue *GV = DstM.getNamedValue(P.first());
GV->setLinkage(GlobalValue::InternalLinkage);
}
if (InternalizeCallback)
InternalizeCallback(DstM, Internalize);
return false;
}
Linker::Linker(Module &M) : Mover(M) {}
bool Linker::linkInModule(std::unique_ptr<Module> Src, unsigned Flags) {
ModuleLinker ModLinker(Mover, std::move(Src), Flags);
bool Linker::linkInModule(
std::unique_ptr<Module> Src, unsigned Flags,
std::function<void(Module &, const StringSet<> &)> InternalizeCallback) {
ModuleLinker ModLinker(Mover, std::move(Src), Flags,
std::move(InternalizeCallback));
return ModLinker.run();
}
@ -571,10 +578,11 @@ bool Linker::linkInModule(std::unique_ptr<Module> Src, unsigned Flags) {
/// true is returned and ErrorMsg (if not null) is set to indicate the problem.
/// Upon failure, the Dest module could be in a modified state, and shouldn't be
/// relied on to be consistent.
bool Linker::linkModules(Module &Dest, std::unique_ptr<Module> Src,
unsigned Flags) {
bool Linker::linkModules(
Module &Dest, std::unique_ptr<Module> Src, unsigned Flags,
std::function<void(Module &, const StringSet<> &)> InternalizeCallback) {
Linker L(Dest);
return L.linkInModule(std::move(Src), Flags);
return L.linkInModule(std::move(Src), Flags, std::move(InternalizeCallback));
}
//===----------------------------------------------------------------------===//

5
test/Linker/Inputs/linkage.d.ll Normal file
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@ -0,0 +1,5 @@
@Y = global i8 42
define i64 @foo() { ret i64 7 }
@llvm.used = appending global [2 x i8*] [i8* @Y, i8* bitcast (i64 ()* @foo to i8*)], section "llvm.metadata"

6
test/Linker/link-flags.ll
View File

@ -2,12 +2,15 @@
; RUN: llvm-link -S -only-needed %S/Inputs/linkage.b.ll %S/Inputs/linkage.c.ll | FileCheck %s -check-prefix=B -check-prefix=C -check-prefix=CN
; RUN: llvm-link -S -internalize %S/Inputs/linkage.b.ll %S/Inputs/linkage.c.ll | FileCheck %s -check-prefix=B -check-prefix=CI
; RUN: llvm-link -S -internalize -only-needed %S/Inputs/linkage.b.ll %S/Inputs/linkage.c.ll | FileCheck %s -check-prefix=B -check-prefix=CN
; RUN: llvm-link -S -internalize %S/Inputs/linkage.b.ll %S/Inputs/linkage.c.ll %S/Inputs/linkage.d.ll | FileCheck %s -check-prefix=B -check-prefix=DI
C-LABEL: @X = global i32 5
CI-LABEL: @X = internal global i32 5
CU-LABEL:@U = global i32 6
CI-LABEL:@U = internal global i32 6
CN-NOT:@U
DI-LABEL: @Y = global i8 42
DI-LABEL: @llvm.used = appending global [2 x i8*] [i8* @Y, i8* bitcast (i64 ()* @foo to i8*)], section "llvm.metadata"
B-LABEL: define void @bar() {
@ -17,3 +20,6 @@ CI-LABEL: define internal i32 @foo()
CU-LABEL:define i32 @unused() {
CI-LABEL:define internal i32 @unused() {
CN-NOT:@unused()
DI-LABEL: define internal i32 @foo.6()
DI-LABEL: define i64 @foo()

23
tools/llvm-link/llvm-link.cpp
View File

@ -34,6 +34,7 @@
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Transforms/IPO/FunctionImport.h"
#include "llvm/Transforms/IPO/Internalize.h"
#include "llvm/Transforms/Utils/FunctionImportUtils.h"
#include <memory>
@ -272,6 +273,8 @@ static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
unsigned Flags) {
// Filter out flags that don't apply to the first file we load.
unsigned ApplicableFlags = Flags & Linker::Flags::OverrideFromSrc;
// Similar to some flags, internalization doesn't apply to the first file.
bool InternalizeLinkedSymbols = false;
for (const auto &File : Files) {
std::unique_ptr<Module> M = loadFile(argv0, File, Context);
if (!M.get()) {
@ -311,8 +314,24 @@ static bool linkFiles(const char *argv0, LLVMContext &Context, Linker &L,
if (Verbose)
errs() << "Linking in '" << File << "'\n";
if (L.linkInModule(std::move(M), ApplicableFlags))
bool Err = false;
if (InternalizeLinkedSymbols) {
Err = L.linkInModule(
std::move(M), ApplicableFlags, [](Module &M, const StringSet<> &GVS) {
internalizeModule(M, [&M, &GVS](const GlobalValue &GV) {
return !GV.hasName() || (GVS.count(GV.getName()) == 0);
});
});
} else {
Err = L.linkInModule(std::move(M), ApplicableFlags);
}
if (Err)
return false;
// Internalization applies to linking of subsequent files.
InternalizeLinkedSymbols = Internalize;
// All linker flags apply to linking of subsequent files.
ApplicableFlags = Flags;
}
@ -340,8 +359,6 @@ int main(int argc, char **argv) {
Linker L(*Composite);
unsigned Flags = Linker::Flags::None;
if (Internalize)
Flags |= Linker::Flags::InternalizeLinkedSymbols;
if (OnlyNeeded)
Flags |= Linker::Flags::LinkOnlyNeeded;