[llvm] r199244 - Reapply "LTO: add API to set strategy for -internalize"
Rafael Espíndola
rafael.espindola at gmail.com
Wed Apr 2 07:16:24 PDT 2014
Sorry I missed this the first time. If I understand it correctly, it
exist so that we don't internalize symbols when using ld -r. Why can't
the linker simply list the symbols that should not be internalized in
that case as it does for every other file?
On 14 January 2014 13:52, Duncan P. N. Exon Smith <dexonsmith at apple.com> wrote:
> Author: dexonsmith
> Date: Tue Jan 14 12:52:17 2014
> New Revision: 199244
>
> URL: http://llvm.org/viewvc/llvm-project?rev=199244&view=rev
> Log:
> Reapply "LTO: add API to set strategy for -internalize"
>
> Reapply r199191, reverted in r199197 because it carelessly broke
> Other/link-opts.ll. The problem was that calling
> createInternalizePass("main") would select
> createInternalizePass(bool("main")) instead of
> createInternalizePass(ArrayRef<const char *>("main")). This commit
> fixes the bug.
>
> The original commit message follows.
>
> Add API to LTOCodeGenerator to specify a strategy for the -internalize
> pass.
>
> This is a new attempt at Bill's change in r185882, which he reverted in
> r188029 due to problems with the gold linker. This puts the onus on the
> linker to decide whether (and what) to internalize.
>
> In particular, running internalize before outputting an object file may
> change a 'weak' symbol into an internal one, even though that symbol
> could be needed by an external object file --- e.g., with arclite.
>
> This patch enables three strategies:
>
> - LTO_INTERNALIZE_FULL: the default (and the old behaviour).
> - LTO_INTERNALIZE_NONE: skip -internalize.
> - LTO_INTERNALIZE_HIDDEN: only -internalize symbols with hidden
> visibility.
>
> LTO_INTERNALIZE_FULL should be used when linking an executable.
>
> Outputting an object file (e.g., via ld -r) is more complicated, and
> depends on whether hidden symbols should be internalized. E.g., for
> ld -r, LTO_INTERNALIZE_NONE can be used when -keep_private_externs, and
> LTO_INTERNALIZE_HIDDEN can be used otherwise. However,
> LTO_INTERNALIZE_FULL is inappropriate, since the output object file will
> eventually need to link with others.
>
> lto_codegen_set_internalize_strategy() sets the strategy for subsequent
> calls to lto_codegen_write_merged_modules() and lto_codegen_compile*().
>
> <rdar://problem/14334895>
>
> Modified:
> llvm/trunk/include/llvm-c/lto.h
> llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h
> llvm/trunk/include/llvm/Transforms/IPO.h
> llvm/trunk/lib/LTO/LTOCodeGenerator.cpp
> llvm/trunk/lib/Transforms/IPO/Internalize.cpp
> llvm/trunk/tools/lto/lto.cpp
>
> Modified: llvm/trunk/include/llvm-c/lto.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm-c/lto.h?rev=199244&r1=199243&r2=199244&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm-c/lto.h (original)
> +++ llvm/trunk/include/llvm-c/lto.h Tue Jan 14 12:52:17 2014
> @@ -40,7 +40,7 @@ typedef bool lto_bool_t;
> * @{
> */
>
> -#define LTO_API_VERSION 5
> +#define LTO_API_VERSION 6
>
> typedef enum {
> LTO_SYMBOL_ALIGNMENT_MASK = 0x0000001F, /* log2 of alignment */
> @@ -73,6 +73,11 @@ typedef enum {
> LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC = 2
> } lto_codegen_model;
>
> +typedef enum {
> + LTO_INTERNALIZE_FULL = 0,
> + LTO_INTERNALIZE_NONE = 1,
> + LTO_INTERNALIZE_HIDDEN = 2
> +} lto_internalize_strategy;
>
> /** opaque reference to a loaded object module */
> typedef struct LTOModule* lto_module_t;
> @@ -264,6 +269,14 @@ lto_codegen_set_assembler_args(lto_code_
> int nargs);
>
> /**
> + * Sets the strategy to use during internalize. Default strategy is
> + * LTO_INTERNALIZE_FULL.
> + */
> +extern void
> +lto_codegen_set_internalize_strategy(lto_code_gen_t cg,
> + lto_internalize_strategy);
> +
> +/**
> * Tells LTO optimization passes that this symbol must be preserved
> * because it is referenced by native code or a command line option.
> */
>
> Modified: llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h?rev=199244&r1=199243&r2=199244&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h (original)
> +++ llvm/trunk/include/llvm/LTO/LTOCodeGenerator.h Tue Jan 14 12:52:17 2014
> @@ -70,6 +70,7 @@ struct LTOCodeGenerator {
> void setTargetOptions(llvm::TargetOptions options);
> void setDebugInfo(lto_debug_model);
> void setCodePICModel(lto_codegen_model);
> + void setInternalizeStrategy(lto_internalize_strategy);
>
> void setCpu(const char *mCpu) { MCpu = mCpu; }
>
> @@ -114,6 +115,14 @@ struct LTOCodeGenerator {
> bool disableGVNLoadPRE,
> std::string &errMsg);
>
> + bool shouldInternalize() const {
> + return InternalizeStrategy != LTO_INTERNALIZE_NONE;
> + }
> +
> + bool shouldOnlyInternalizeHidden() const {
> + return InternalizeStrategy == LTO_INTERNALIZE_HIDDEN;
> + }
> +
> private:
> void initializeLTOPasses();
>
> @@ -138,6 +147,7 @@ private:
> bool EmitDwarfDebugInfo;
> bool ScopeRestrictionsDone;
> lto_codegen_model CodeModel;
> + lto_internalize_strategy InternalizeStrategy;
> StringSet MustPreserveSymbols;
> StringSet AsmUndefinedRefs;
> llvm::MemoryBuffer *NativeObjectFile;
>
> Modified: llvm/trunk/include/llvm/Transforms/IPO.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO.h?rev=199244&r1=199243&r2=199244&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/Transforms/IPO.h (original)
> +++ llvm/trunk/include/llvm/Transforms/IPO.h Tue Jan 14 12:52:17 2014
> @@ -108,14 +108,19 @@ Pass *createPruneEHPass();
> ////
> /// The symbols in \p ExportList are never internalized.
> ///
> +/// When OnlyHidden=true, only symbols with hidden visibility are internalized.
> +///
> /// The symbol in DSOList are internalized if it is safe to drop them from
> /// the symbol table.
> ///
> /// Note that commandline options that are used with the above function are not
> /// used now!
> -ModulePass *createInternalizePass(ArrayRef<const char *> ExportList);
> +ModulePass *createInternalizePass(ArrayRef<const char *> ExportList,
> + bool OnlyHidden = false);
> /// createInternalizePass - Same as above, but with an empty exportList.
> -ModulePass *createInternalizePass();
> +ModulePass *createInternalizePass(bool OnlyHidden = false);
> +/// createInternalizePass - Resolve ambiguity when passed a const char *.
> +ModulePass *createInternalizePass(const char *SingleExport);
>
> //===----------------------------------------------------------------------===//
> /// createDeadArgEliminationPass - This pass removes arguments from functions
>
> Modified: llvm/trunk/lib/LTO/LTOCodeGenerator.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/LTO/LTOCodeGenerator.cpp?rev=199244&r1=199243&r2=199244&view=diff
> ==============================================================================
> --- llvm/trunk/lib/LTO/LTOCodeGenerator.cpp (original)
> +++ llvm/trunk/lib/LTO/LTOCodeGenerator.cpp Tue Jan 14 12:52:17 2014
> @@ -62,7 +62,8 @@ const char* LTOCodeGenerator::getVersion
> LTOCodeGenerator::LTOCodeGenerator()
> : Context(getGlobalContext()), Linker(new Module("ld-temp.o", Context)),
> TargetMach(NULL), EmitDwarfDebugInfo(false), ScopeRestrictionsDone(false),
> - CodeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC), NativeObjectFile(NULL) {
> + CodeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
> + InternalizeStrategy(LTO_INTERNALIZE_FULL), NativeObjectFile(NULL) {
> initializeLTOPasses();
> }
>
> @@ -164,6 +165,18 @@ void LTOCodeGenerator::setCodePICModel(l
> llvm_unreachable("Unknown PIC model!");
> }
>
> +void
> +LTOCodeGenerator::setInternalizeStrategy(lto_internalize_strategy Strategy) {
> + switch (Strategy) {
> + case LTO_INTERNALIZE_FULL:
> + case LTO_INTERNALIZE_NONE:
> + case LTO_INTERNALIZE_HIDDEN:
> + InternalizeStrategy = Strategy;
> + return;
> + }
> + llvm_unreachable("Unknown internalize strategy!");
> +}
> +
> bool LTOCodeGenerator::writeMergedModules(const char *path,
> std::string &errMsg) {
> if (!determineTarget(errMsg))
> @@ -377,7 +390,7 @@ static void accumulateAndSortLibcalls(st
> }
>
> void LTOCodeGenerator::applyScopeRestrictions() {
> - if (ScopeRestrictionsDone)
> + if (ScopeRestrictionsDone || !shouldInternalize())
> return;
> Module *mergedModule = Linker.getModule();
>
> @@ -429,7 +442,8 @@ void LTOCodeGenerator::applyScopeRestric
> LLVMCompilerUsed->setSection("llvm.metadata");
> }
>
> - passes.add(createInternalizePass(MustPreserveList));
> + passes.add(
> + createInternalizePass(MustPreserveList, shouldOnlyInternalizeHidden()));
>
> // apply scope restrictions
> passes.run(*mergedModule);
>
> Modified: llvm/trunk/lib/Transforms/IPO/Internalize.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/Internalize.cpp?rev=199244&r1=199243&r2=199244&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Transforms/IPO/Internalize.cpp (original)
> +++ llvm/trunk/lib/Transforms/IPO/Internalize.cpp Tue Jan 14 12:52:17 2014
> @@ -54,10 +54,11 @@ APIList("internalize-public-api-list", c
> namespace {
> class InternalizePass : public ModulePass {
> std::set<std::string> ExternalNames;
> + bool OnlyHidden;
> public:
> static char ID; // Pass identification, replacement for typeid
> - explicit InternalizePass();
> - explicit InternalizePass(ArrayRef<const char *> ExportList);
> + explicit InternalizePass(bool OnlyHidden = false);
> + explicit InternalizePass(ArrayRef<const char *> ExportList, bool OnlyHidden);
> void LoadFile(const char *Filename);
> virtual bool runOnModule(Module &M);
>
> @@ -72,16 +73,17 @@ char InternalizePass::ID = 0;
> INITIALIZE_PASS(InternalizePass, "internalize",
> "Internalize Global Symbols", false, false)
>
> -InternalizePass::InternalizePass()
> - : ModulePass(ID) {
> +InternalizePass::InternalizePass(bool OnlyHidden)
> + : ModulePass(ID), OnlyHidden(OnlyHidden) {
> initializeInternalizePassPass(*PassRegistry::getPassRegistry());
> if (!APIFile.empty()) // If a filename is specified, use it.
> LoadFile(APIFile.c_str());
> ExternalNames.insert(APIList.begin(), APIList.end());
> }
>
> -InternalizePass::InternalizePass(ArrayRef<const char *> ExportList)
> - : ModulePass(ID){
> +InternalizePass::InternalizePass(ArrayRef<const char *> ExportList,
> + bool OnlyHidden)
> + : ModulePass(ID), OnlyHidden(OnlyHidden) {
> initializeInternalizePassPass(*PassRegistry::getPassRegistry());
> for(ArrayRef<const char *>::const_iterator itr = ExportList.begin();
> itr != ExportList.end(); itr++) {
> @@ -106,7 +108,11 @@ void InternalizePass::LoadFile(const cha
> }
>
> static bool shouldInternalize(const GlobalValue &GV,
> - const std::set<std::string> &ExternalNames) {
> + const std::set<std::string> &ExternalNames,
> + bool OnlyHidden) {
> + if (OnlyHidden && !GV.hasHiddenVisibility())
> + return false;
> +
> // Function must be defined here
> if (GV.isDeclaration())
> return false;
> @@ -155,9 +161,8 @@ bool InternalizePass::runOnModule(Module
> }
>
> // Mark all functions not in the api as internal.
> - // FIXME: maybe use private linkage?
> for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
> - if (!shouldInternalize(*I, ExternalNames))
> + if (!shouldInternalize(*I, ExternalNames, OnlyHidden))
> continue;
>
> I->setLinkage(GlobalValue::InternalLinkage);
> @@ -191,10 +196,9 @@ bool InternalizePass::runOnModule(Module
>
> // Mark all global variables with initializers that are not in the api as
> // internal as well.
> - // FIXME: maybe use private linkage?
> for (Module::global_iterator I = M.global_begin(), E = M.global_end();
> I != E; ++I) {
> - if (!shouldInternalize(*I, ExternalNames))
> + if (!shouldInternalize(*I, ExternalNames, OnlyHidden))
> continue;
>
> I->setLinkage(GlobalValue::InternalLinkage);
> @@ -206,7 +210,7 @@ bool InternalizePass::runOnModule(Module
> // Mark all aliases that are not in the api as internal as well.
> for (Module::alias_iterator I = M.alias_begin(), E = M.alias_end();
> I != E; ++I) {
> - if (!shouldInternalize(*I, ExternalNames))
> + if (!shouldInternalize(*I, ExternalNames, OnlyHidden))
> continue;
>
> I->setLinkage(GlobalValue::InternalLinkage);
> @@ -218,10 +222,15 @@ bool InternalizePass::runOnModule(Module
> return Changed;
> }
>
> -ModulePass *llvm::createInternalizePass() {
> - return new InternalizePass();
> +ModulePass *llvm::createInternalizePass(bool OnlyHidden) {
> + return new InternalizePass(OnlyHidden);
> +}
> +
> +ModulePass *llvm::createInternalizePass(ArrayRef<const char *> ExportList,
> + bool OnlyHidden) {
> + return new InternalizePass(ExportList, OnlyHidden);
> }
>
> -ModulePass *llvm::createInternalizePass(ArrayRef<const char *> ExportList) {
> - return new InternalizePass(ExportList);
> +ModulePass *llvm::createInternalizePass(const char *SingleExport) {
> + return createInternalizePass(ArrayRef<const char *>(SingleExport));
> }
>
> Modified: llvm/trunk/tools/lto/lto.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/lto/lto.cpp?rev=199244&r1=199243&r2=199244&view=diff
> ==============================================================================
> --- llvm/trunk/tools/lto/lto.cpp (original)
> +++ llvm/trunk/tools/lto/lto.cpp Tue Jan 14 12:52:17 2014
> @@ -252,6 +252,13 @@ void lto_codegen_set_assembler_args(lto_
> // In here only for backwards compatibility. We use MC now.
> }
>
> +/// lto_codegen_set_internalize_strategy - Sets the strategy to use during
> +/// internalize.
> +void lto_codegen_set_internalize_strategy(lto_code_gen_t cg,
> + lto_internalize_strategy strategy) {
> + cg->setInternalizeStrategy(strategy);
> +}
> +
> /// lto_codegen_add_must_preserve_symbol - Adds to a list of all global symbols
> /// that must exist in the final generated code. If a function is not listed
> /// there, it might be inlined into every usage and optimized away.
>
>
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