[lld] r221584 - [ELF] Support -z max-page-size option

[Rui Ueyama]

On Mon, Nov 10, 2014 at 6:54 AM, Shankar Easwaran <shankare at codeaurora.org>
wrote:

> Author: shankare
> Date: Mon Nov 10 08:54:43 2014
> New Revision: 221584
>
> URL: http://llvm.org/viewvc/llvm-project?rev=221584&view=rev
> Log:
> [ELF] Support -z max-page-size option
>
> The GNU linker allows the user to change the page size by using the option
> -z
> max-page-size.
>
> Modified:
>     lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h
>     lld/trunk/lib/Driver/GnuLdDriver.cpp
>     lld/trunk/lib/ReaderWriter/ELF/ELFLinkingContext.cpp
>
> Modified: lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h?rev=221584&r1=221583&r2=221584&view=diff
>
> ==============================================================================
> --- lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h (original)
> +++ lld/trunk/include/lld/ReaderWriter/ELFLinkingContext.h Mon Nov 10
> 08:54:43 2014
> @@ -58,7 +58,19 @@ public:
>    };
>
>    llvm::Triple getTriple() const { return _triple; }
> -  virtual uint64_t getPageSize() const { return 0x1000; }
> +
> +  // Page size.
> +  virtual uint64_t getPageSize() const {
> +    if (_maxPageSizeOptionSet)
> +      return _maxPageSize;
> +    return 0x1000;
> +  }
> +  virtual void setMaxPageSize(uint64_t pagesize) {
> +    _maxPageSize = pagesize;
> +    _maxPageSizeOptionSet = true;
> +  }
> +  virtual uint64_t maxPageSize() const { return _maxPageSize; }
> +
>    OutputMagic getOutputMagic() const { return _outputMagic; }
>    uint16_t getOutputELFType() const { return _outputELFType; }
>    uint16_t getOutputMachine() const;
> @@ -308,6 +320,9 @@ protected:
>    bool _mergeRODataToTextSegment;
>    bool _demangle;
>    bool _alignSegments;
> +  bool _maxPageSizeOptionSet;
> +  uint64_t _maxPageSize;
>

Maybe this is a place you want to use llvm::Optional<uint64_t> instead of
having two fields for one value?

+
>    OutputMagic _outputMagic;
>    StringRefVector _inputSearchPaths;
>    std::unique_ptr<Writer> _writer;
>
> Modified: lld/trunk/lib/Driver/GnuLdDriver.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/lib/Driver/GnuLdDriver.cpp?rev=221584&r1=221583&r2=221584&view=diff
>
> ==============================================================================
> --- lld/trunk/lib/Driver/GnuLdDriver.cpp (original)
> +++ lld/trunk/lib/Driver/GnuLdDriver.cpp Mon Nov 10 08:54:43 2014
> @@ -15,6 +15,7 @@
>
>  #include "lld/Driver/Driver.h"
>  #include "lld/Driver/GnuLdInputGraph.h"
> +#include "lld/Support/NumParse.h"
>  #include "llvm/ADT/ArrayRef.h"
>  #include "llvm/ADT/Optional.h"
>  #include "llvm/ADT/STLExtras.h"
> @@ -151,6 +152,22 @@ static bool parseDefsymAsAlias(StringRef
>    return !target.empty();
>  }
>
> +// Parses dashz options for max-page-size.
> +static bool parseZOption(StringRef opt, uint64_t &val) {
> +  size_t equalPos = opt.find('=');
> +  if (equalPos == 0 || equalPos == StringRef::npos)
> +    return false;
> +  StringRef value = opt.substr(equalPos + 1);
> +  ErrorOr<uint64_t> parsedVal = lld::parseNum(value, false /*No
> Extensions*/);
> +  if (!parsedVal)
> +    return false;
> +  // Dont allow a value of 0 for max-page-size.
> +  val = parsedVal.get();
> +  if (!val)
> +    return false;
> +  return true;
> +}
> +
>  llvm::ErrorOr<StringRef> ELFFileNode::getPath(const LinkingContext &)
> const {
>    if (_attributes._isDashlPrefix)
>      return _elfLinkingContext.searchLibrary(_path);
> @@ -471,7 +488,25 @@ bool GnuLdDriver::parse(int argc, const
>        StringRef extOpt = inputArg->getValue();
>        if (extOpt == "muldefs")
>          ctx->setAllowDuplicates(true);
> -      else
> +      else if (extOpt.startswith("max-page-size")) {
> +        // Parse -z max-page-size option.
> +        // The default page size is considered the minimum page size the
> user
> +        // can set, check the user input if its atleast the minimum page
> size
> +        // and doesnot exceed the maximum page size allowed for the
> target.
> +        uint64_t maxPageSize = 0;
> +
> +        // Error if the page size user set is less than the maximum page
> size
> +        // and greather than the default page size and the user page size
> is a
> +        // modulo of the default page size.
> +        if ((!parseZOption(extOpt, maxPageSize)) ||
> +            (maxPageSize < ctx->getPageSize()) ||
> +            (maxPageSize > ctx->maxPageSize()) ||
> +            (!maxPageSize % ctx->maxPageSize())) {
> +          diagnostics << "invalid option: " << extOpt << "\n";
> +          return false;
> +        }
> +        ctx->setMaxPageSize(maxPageSize);
> +      } else
>          diagnostics << "warning: ignoring unknown argument for -z: " <<
> extOpt
>                      << "\n";
>        break;
>
> Modified: lld/trunk/lib/ReaderWriter/ELF/ELFLinkingContext.cpp
> URL:
> http://llvm.org/viewvc/llvm-project/lld/trunk/lib/ReaderWriter/ELF/ELFLinkingContext.cpp?rev=221584&r1=221583&r2=221584&view=diff
>
> ==============================================================================
> --- lld/trunk/lib/ReaderWriter/ELF/ELFLinkingContext.cpp (original)
> +++ lld/trunk/lib/ReaderWriter/ELF/ELFLinkingContext.cpp Mon Nov 10
> 08:54:43 2014
> @@ -62,7 +62,8 @@ ELFLinkingContext::ELFLinkingContext(
>        _mergeCommonStrings(false), _runLayoutPass(true),
>        _useShlibUndefines(true), _dynamicLinkerArg(false),
>        _noAllowDynamicLibraries(false), _mergeRODataToTextSegment(true),
> -      _demangle(true), _alignSegments(true),
> _outputMagic(OutputMagic::DEFAULT),
> +      _demangle(true), _alignSegments(true), _maxPageSizeOptionSet(false),
> +      _maxPageSize(0x10000), _outputMagic(OutputMagic::DEFAULT),
>        _sysrootPath("") {}
>
>  void ELFLinkingContext::addPasses(PassManager &pm) {
>
>
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