[llvm] r204398 - Add an option to MCJIT to have it forward all sections to the
Philip Reames
listmail at philipreames.com
Thu Mar 20 16:57:42 PDT 2014
In this case, I might vote for changing the default. Given the old
behaviour is unlikely to be correct, I don't see the benefit in keeping
it as the default.
Philip
On 03/20/2014 02:06 PM, Lang Hames wrote:
> Author: lhames
> Date: Thu Mar 20 16:06:46 2014
> New Revision: 204398
>
> URL: http://llvm.org/viewvc/llvm-project?rev=204398&view=rev
> Log:
> Add an option to MCJIT to have it forward all sections to the
> RTDyldMemoryManager, regardless of whether it thinks they're "required for
> execution".
>
> Currently, RuntimeDyld only passes sections that are "required for execution"
> to the RTDyldMemoryManager, and takes "required for execution" to mean exactly
> "contains symbols or relocations". There are two problems with this:
> (1) It can drop sections with anonymous data that is referenced by code.
> (2) It leaves the JIT client no way to inspect interesting sections that aren't
> actually required to run the program (e.g dwarf sections).
>
> A test case is still in the works.
>
> Future work: We may want to replace this with a generic section filtering
> mechanism, but that will require more consideration. For now, this flag at least
> allows clients to volunteer to do the filtering themselves.
>
> Fixes <rdar://problem/15177691>.
>
>
> Modified:
> llvm/trunk/include/llvm/ExecutionEngine/ExecutionEngine.h
> llvm/trunk/include/llvm/ExecutionEngine/RuntimeDyld.h
> llvm/trunk/lib/ExecutionEngine/MCJIT/MCJIT.h
> llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
> llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
>
> Modified: llvm/trunk/include/llvm/ExecutionEngine/ExecutionEngine.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ExecutionEngine/ExecutionEngine.h?rev=204398&r1=204397&r2=204398&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/ExecutionEngine/ExecutionEngine.h (original)
> +++ llvm/trunk/include/llvm/ExecutionEngine/ExecutionEngine.h Thu Mar 20 16:06:46 2014
> @@ -462,6 +462,21 @@ public:
> llvm_unreachable("No support for an object cache");
> }
>
> + /// setProcessAllSections (MCJIT Only): By default, only sections that are
> + /// "required for execution" are passed to the RTDyldMemoryManager, and other
> + /// sections are discarded. Passing 'true' to this method will cause
> + /// RuntimeDyld to pass all sections to its RTDyldMemoryManager regardless
> + /// of whether they are "required to execute" in the usual sense.
> + ///
> + /// Rationale: Some MCJIT clients want to be able to inspect metadata
> + /// sections (e.g. Dwarf, Stack-maps) to enable functionality or analyze
> + /// performance. Passing these sections to the memory manager allows the
> + /// client to make policy about the relevant sections, rather than having
> + /// MCJIT do it.
> + virtual void setProcessAllSections(bool ProcessAllSections) {
> + llvm_unreachable("No support for ProcessAllSections option");
> + }
> +
> /// Return the target machine (if available).
> virtual TargetMachine *getTargetMachine() { return NULL; }
>
>
> Modified: llvm/trunk/include/llvm/ExecutionEngine/RuntimeDyld.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/ExecutionEngine/RuntimeDyld.h?rev=204398&r1=204397&r2=204398&view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/ExecutionEngine/RuntimeDyld.h (original)
> +++ llvm/trunk/include/llvm/ExecutionEngine/RuntimeDyld.h Thu Mar 20 16:06:46 2014
> @@ -36,6 +36,7 @@ class RuntimeDyld {
> // interface.
> RuntimeDyldImpl *Dyld;
> RTDyldMemoryManager *MM;
> + bool ProcessAllSections;
> protected:
> // Change the address associated with a section when resolving relocations.
> // Any relocations already associated with the symbol will be re-resolved.
> @@ -84,6 +85,19 @@ public:
> void deregisterEHFrames();
>
> StringRef getErrorString();
> +
> + /// By default, only sections that are "required for execution" are passed to
> + /// the RTDyldMemoryManager, and other sections are discarded. Passing 'true'
> + /// to this method will cause RuntimeDyld to pass all sections to its
> + /// memory manager regardless of whether they are "required to execute" in the
> + /// usual sense. This is useful for inspecting metadata sections that may not
> + /// contain relocations, E.g. Debug info, stackmaps.
> + ///
> + /// Must be called before the first object file is loaded.
> + void setProcessAllSections(bool ProcessAllSections) {
> + assert(!Dyld && "setProcessAllSections must be called before loadObject.");
> + this->ProcessAllSections = ProcessAllSections;
> + }
> };
>
> } // end namespace llvm
>
> Modified: llvm/trunk/lib/ExecutionEngine/MCJIT/MCJIT.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/MCJIT/MCJIT.h?rev=204398&r1=204397&r2=204398&view=diff
> ==============================================================================
> --- llvm/trunk/lib/ExecutionEngine/MCJIT/MCJIT.h (original)
> +++ llvm/trunk/lib/ExecutionEngine/MCJIT/MCJIT.h Thu Mar 20 16:06:46 2014
> @@ -251,6 +251,10 @@ public:
> /// Sets the object manager that MCJIT should use to avoid compilation.
> void setObjectCache(ObjectCache *manager) override;
>
> + void setProcessAllSections(bool ProcessAllSections) override {
> + Dyld.setProcessAllSections(ProcessAllSections);
> + }
> +
> void generateCodeForModule(Module *M) override;
>
> /// finalizeObject - ensure the module is fully processed and is usable.
>
> Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp?rev=204398&r1=204397&r2=204398&view=diff
> ==============================================================================
> --- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp (original)
> +++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyld.cpp Thu Mar 20 16:06:46 2014
> @@ -161,25 +161,22 @@ ObjectImage* RuntimeDyldImpl::loadObject
> DEBUG(dbgs() << "Parse relocations:\n");
> for (section_iterator SI = Obj->begin_sections(), SE = Obj->end_sections();
> SI != SE; ++SI) {
> - bool IsFirstRelocation = true;
> unsigned SectionID = 0;
> StubMap Stubs;
> section_iterator RelocatedSection = SI->getRelocatedSection();
>
> - for (const RelocationRef &Reloc : SI->relocations()) {
> - // If it's the first relocation in this section, find its SectionID
> - if (IsFirstRelocation) {
> - bool IsCode = false;
> - Check(RelocatedSection->isText(IsCode));
> - SectionID =
> - findOrEmitSection(*Obj, *RelocatedSection, IsCode, LocalSections);
> - DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
> - IsFirstRelocation = false;
> - }
> + if ((SI->relocation_begin() != SI->relocation_end()) ||
> + ProcessAllSections) {
> + bool IsCode = false;
> + Check(RelocatedSection->isText(IsCode));
> + SectionID =
> + findOrEmitSection(*Obj, *RelocatedSection, IsCode, LocalSections);
> + DEBUG(dbgs() << "\tSectionID: " << SectionID << "\n");
> + }
>
> + for (const RelocationRef &Reloc : SI->relocations())
> processRelocationRef(SectionID, Reloc, *Obj, LocalSections, LocalSymbols,
> Stubs);
> - }
> }
>
> // Give the subclasses a chance to tie-up any loose ends.
> @@ -665,23 +662,40 @@ RuntimeDyld::RuntimeDyld(RTDyldMemoryMan
> // permissions are applied.
> Dyld = 0;
> MM = mm;
> + ProcessAllSections = false;
> }
>
> RuntimeDyld::~RuntimeDyld() {
> delete Dyld;
> }
>
> +static std::unique_ptr<RuntimeDyldELF> createRuntimeDyldELF(
> + RTDyldMemoryManager *MM,
> + bool ProcessAllSections) {
> + std::unique_ptr<RuntimeDyldELF> Dyld(new RuntimeDyldELF(MM));
> + Dyld->setProcessAllSections(ProcessAllSections);
> + return Dyld;
> +}
> +
> +static std::unique_ptr<RuntimeDyldMachO> createRuntimeDyldMachO(
> + RTDyldMemoryManager *MM,
> + bool ProcessAllSections) {
> + std::unique_ptr<RuntimeDyldMachO> Dyld(new RuntimeDyldMachO(MM));
> + Dyld->setProcessAllSections(ProcessAllSections);
> + return Dyld;
> +}
> +
> ObjectImage *RuntimeDyld::loadObject(ObjectFile *InputObject) {
> std::unique_ptr<ObjectImage> InputImage;
>
> if (InputObject->isELF()) {
> InputImage.reset(RuntimeDyldELF::createObjectImageFromFile(InputObject));
> if (!Dyld)
> - Dyld = new RuntimeDyldELF(MM);
> + Dyld = createRuntimeDyldELF(MM, ProcessAllSections).release();
> } else if (InputObject->isMachO()) {
> InputImage.reset(RuntimeDyldMachO::createObjectImageFromFile(InputObject));
> if (!Dyld)
> - Dyld = new RuntimeDyldMachO(MM);
> + Dyld = createRuntimeDyldMachO(MM, ProcessAllSections).release();
> } else
> report_fatal_error("Incompatible object format!");
>
> @@ -704,7 +718,7 @@ ObjectImage *RuntimeDyld::loadObject(Obj
> case sys::fs::file_magic::elf_core:
> InputImage.reset(RuntimeDyldELF::createObjectImage(InputBuffer));
> if (!Dyld)
> - Dyld = new RuntimeDyldELF(MM);
> + Dyld = createRuntimeDyldELF(MM, ProcessAllSections).release();
> break;
> case sys::fs::file_magic::macho_object:
> case sys::fs::file_magic::macho_executable:
> @@ -718,7 +732,7 @@ ObjectImage *RuntimeDyld::loadObject(Obj
> case sys::fs::file_magic::macho_dsym_companion:
> InputImage.reset(RuntimeDyldMachO::createObjectImage(InputBuffer));
> if (!Dyld)
> - Dyld = new RuntimeDyldMachO(MM);
> + Dyld = createRuntimeDyldMachO(MM, ProcessAllSections).release();
> break;
> case sys::fs::file_magic::unknown:
> case sys::fs::file_magic::bitcode:
>
> Modified: llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h?rev=204398&r1=204397&r2=204398&view=diff
> ==============================================================================
> --- llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h (original)
> +++ llvm/trunk/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldImpl.h Thu Mar 20 16:06:46 2014
> @@ -187,6 +187,10 @@ protected:
> Triple::ArchType Arch;
> bool IsTargetLittleEndian;
>
> + // True if all sections should be passed to the memory manager, false if only
> + // sections containing relocations should be. Defaults to 'false'.
> + bool ProcessAllSections;
> +
> // This mutex prevents simultaneously loading objects from two different
> // threads. This keeps us from having to protect individual data structures
> // and guarantees that section allocation requests to the memory manager
> @@ -320,10 +324,15 @@ protected:
> unsigned computeSectionStubBufSize(ObjectImage &Obj, const SectionRef &Section);
>
> public:
> - RuntimeDyldImpl(RTDyldMemoryManager *mm) : MemMgr(mm), HasError(false) {}
> + RuntimeDyldImpl(RTDyldMemoryManager *mm)
> + : MemMgr(mm), ProcessAllSections(false), HasError(false) {}
>
> virtual ~RuntimeDyldImpl();
>
> + void setProcessAllSections(bool ProcessAllSections) {
> + this->ProcessAllSections = ProcessAllSections;
> + }
> +
> ObjectImage* loadObject(ObjectImage* InputObject);
>
> void *getSymbolAddress(StringRef Name) {
>
>
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