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  1. Apr 09, 2012
  2. Apr 08, 2012
    • Chandler Carruth's avatar
      Teach LLVM about a PIE option which, when enabled on top of PIC, makes · ede4a8aa
      Chandler Carruth authored
      optimizations which are valid for position independent code being linked
      into a single executable, but not for such code being linked into
      a shared library.
      
      I discussed the design of this with Eric Christopher, and the decision
      was to support an optional bit rather than a completely separate
      relocation model. Fundamentally, this is still PIC relocation, its just
      that certain optimizations are only valid under a PIC relocation model
      when the resulting code won't be in a shared library. The simplest path
      to here is to expose a single bit option in the TargetOptions. If folks
      have different/better designs, I'm all ears. =]
      
      I've included the first optimization based upon this: changing TLS
      models to the *Exec models when PIE is enabled. This is the LLVM
      component of PR12380 and is all of the hard work.
      
      llvm-svn: 154294
      ede4a8aa
    • Chandler Carruth's avatar
      Move the TLSModel information into the TargetMachine rather than hiding · 16f0ebcb
      Chandler Carruth authored
      in TargetLowering. There was already a FIXME about this location being
      odd. The interface is simplified as a consequence. This will also make
      it easier to change TLS models when compiling with PIE.
      
      llvm-svn: 154292
      16f0ebcb
    • Bill Wendling's avatar
      Allow subclasses of the ValueHandleBase to store information as part of the · 9b2503a0
      Bill Wendling authored
      value pointer by making the value pointer into a pointer-int pair with 2 bits
      available for flags.
      
      llvm-svn: 154279
      9b2503a0
  3. Apr 07, 2012
    • Chandler Carruth's avatar
      Perform partial SROA on the helper hashing structure. I really wish the · 75a1cf32
      Chandler Carruth authored
      optimizers could do this for us, but expecting partial SROA of classes
      with template methods through cloning is probably expecting too much
      heroics. With this change, the begin/end pointer pairs which indicate
      the status of each loop iteration are actually passed directly into each
      layer of the combine_data calls, and the inliner has a chance to see
      when most of the combine_data function could be deleted by inlining.
      Similarly for 'length'.
      
      We have to be careful to limit the places where in/out reference
      parameters are used as those will also defeat the inliner / optimizers
      from properly propagating constants.
      
      With this change, LLVM is able to fully inline and unroll the hash
      computation of small sets of values, such as two or three pointers.
      These now decompose into essentially straight-line code with no loops or
      function calls.
      
      There is still one code quality problem to be solved with the hashing --
      LLVM is failing to nuke the alloca. It removes all loads from the
      alloca, leaving only lifetime intrinsics and dead(!!) stores to the
      alloca. =/ Very unfortunate.
      
      llvm-svn: 154264
      75a1cf32
    • Hongbin Zheng's avatar
      Refactor: Use positive field names in VectorizeConfig. · 5758f495
      Hongbin Zheng authored
      llvm-svn: 154249
      5758f495
    • Alexis Hunt's avatar
      Output UTF-8-encoded characters as identifier characters into assembly · 0235f684
      Alexis Hunt authored
      by default.
      
      This is a behaviour configurable in the MCAsmInfo. I've decided to turn
      it on by default in (possibly optimistic) hopes that most assemblers are
      reasonably sane. If this proves a problem, switching to default seems
      reasonable.
      
      I'm not sure if this is the opportune place to test, but it seemed good
      to make sure it was tested somewhere.
      
      llvm-svn: 154235
      0235f684
  4. Apr 06, 2012
  5. Apr 05, 2012
  6. Apr 04, 2012
  7. Apr 03, 2012
  8. Apr 02, 2012
  9. Apr 01, 2012
  10. Mar 31, 2012
    • Rafael Espindola's avatar
      Add a workaround for building with old versions of clang. · 1eaae507
      Rafael Espindola authored
      llvm-svn: 153820
      1eaae507
    • Rafael Espindola's avatar
      Teach CodeGen's version of computeMaskedBits to understand the range metadata. · 80c540e6
      Rafael Espindola authored
      This is the CodeGen equivalent of r153747. I tested that there is not noticeable
      performance difference with any combination of -O0/-O2 /-g when compiling
      gcc as a single compilation unit.
      
      llvm-svn: 153817
      80c540e6
    • Chandler Carruth's avatar
      Remove a bunch of empty, dead, and no-op methods from all of these · edd2826f
      Chandler Carruth authored
      interfaces. These methods were used in the old inline cost system where
      there was a persistent cache that had to be updated, invalidated, and
      cleared. We're now doing more direct computations that don't require
      this intricate dance. Even if we resume some level of caching, it would
      almost certainly have a simpler and more narrow interface than this.
      
      llvm-svn: 153813
      edd2826f
    • Chandler Carruth's avatar
      Initial commit for the rewrite of the inline cost analysis to operate · 0539c071
      Chandler Carruth authored
      on a per-callsite walk of the called function's instructions, in
      breadth-first order over the potentially reachable set of basic blocks.
      
      This is a major shift in how inline cost analysis works to improve the
      accuracy and rationality of inlining decisions. A brief outline of the
      algorithm this moves to:
      
      - Build a simplification mapping based on the callsite arguments to the
        function arguments.
      - Push the entry block onto a worklist of potentially-live basic blocks.
      - Pop the first block off of the *front* of the worklist (for
        breadth-first ordering) and walk its instructions using a custom
        InstVisitor.
      - For each instruction's operands, re-map them based on the
        simplification mappings available for the given callsite.
      - Compute any simplification possible of the instruction after
        re-mapping, and store that back int othe simplification mapping.
      - Compute any bonuses, costs, or other impacts of the instruction on the
        cost metric.
      - When the terminator is reached, replace any conditional value in the
        terminator with any simplifications from the mapping we have, and add
        any successors which are not proven to be dead from these
        simplifications to the worklist.
      - Pop the next block off of the front of the worklist, and repeat.
      - As soon as the cost of inlining exceeds the threshold for the
        callsite, stop analyzing the function in order to bound cost.
      
      The primary goal of this algorithm is to perfectly handle dead code
      paths. We do not want any code in trivially dead code paths to impact
      inlining decisions. The previous metric was *extremely* flawed here, and
      would always subtract the average cost of two successors of
      a conditional branch when it was proven to become an unconditional
      branch at the callsite. There was no handling of wildly different costs
      between the two successors, which would cause inlining when the path
      actually taken was too large, and no inlining when the path actually
      taken was trivially simple. There was also no handling of the code
      *path*, only the immediate successors. These problems vanish completely
      now. See the added regression tests for the shiny new features -- we
      skip recursive function calls, SROA-killing instructions, and high cost
      complex CFG structures when dead at the callsite being analyzed.
      
      Switching to this algorithm required refactoring the inline cost
      interface to accept the actual threshold rather than simply returning
      a single cost. The resulting interface is pretty bad, and I'm planning
      to do lots of interface cleanup after this patch.
      
      Several other refactorings fell out of this, but I've tried to minimize
      them for this patch. =/ There is still more cleanup that can be done
      here. Please point out anything that you see in review.
      
      I've worked really hard to try to mirror at least the spirit of all of
      the previous heuristics in the new model. It's not clear that they are
      all correct any more, but I wanted to minimize the change in this single
      patch, it's already a bit ridiculous. One heuristic that is *not* yet
      mirrored is to allow inlining of functions with a dynamic alloca *if*
      the caller has a dynamic alloca. I will add this back, but I think the
      most reasonable way requires changes to the inliner itself rather than
      just the cost metric, and so I've deferred this for a subsequent patch.
      The test case is XFAIL-ed until then.
      
      As mentioned in the review mail, this seems to make Clang run about 1%
      to 2% faster in -O0, but makes its binary size grow by just under 4%.
      I've looked into the 4% growth, and it can be fixed, but requires
      changes to other parts of the inliner.
      
      llvm-svn: 153812
      0539c071
    • Chandler Carruth's avatar
      Add support to the InstVisitor for visiting a generic callsite. The · 056b4609
      Chandler Carruth authored
      visitor will now visit a CallInst and an InvokeInst with
      instruction-specific visitors, then visit a generic CallSite visitor,
      then delegate back to the Instruction visitor and the TerminatorInst
      visitors depending on whether a call or an invoke originally. This will
      be used in the soon-to-land inline cost rewrite.
      
      llvm-svn: 153811
      056b4609
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