Commit 9d20e427 authored by Mark Heffernan's avatar Mark Heffernan
Browse files

Rename metadata llvm.loop.vectorize.unroll to llvm.loop.vectorize.interleave. 

llvm-svn: 213588
parent 34735af3

llvm/docs/LangRef.rst

+31 −19
Original line number Diff line number Diff line
@@ -2910,37 +2910,49 @@ suggests an unroll factor to the loop unroller: 
      br i1 %exitcond, label %._crit_edge, label %.lr.ph, !llvm.loop !0

    ...

    !0 = metadata !{ metadata !0, metadata !1 }

    !1 = metadata !{ metadata !"llvm.loop.vectorize.width", i32 4 }

    !1 = metadata !{ metadata !"llvm.loop.unroll.count", i32 4 }



'``llvm.loop.vectorize``'

^^^^^^^^^^^^^^^^^^^^^^^^^

'``llvm.loop.vectorize``' and '``llvm.loop.interleave``'

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^



Metadata prefixed with ``llvm.loop.vectorize`` is used to control

per-loop vectorization parameters such as vectorization width and

interleave count.  ``llvm.loop.vectorize`` metadata should be used in

Metadata prefixed with ``llvm.loop.vectorize`` or ``llvm.loop.interleave`` are

used to control per-loop vectorization and interleaving parameters such as

vectorization width and interleave count.  These metadata should be used in

conjunction with ``llvm.loop`` loop identification metadata.  The

``llvm.loop.vectorize`` metadata are only optimization hints and the

vectorizer will only vectorize loops if it believes it is safe to do

so.  The ``llvm.mem.parallel_loop_access`` metadata which contains

information about loop-carried memory dependencies can be helpful in

determining the safety of loop vectorization.

``llvm.loop.vectorize`` and ``llvm.loop.interleave`` metadata are only

optimization hints and the optimizer will only interleave and vectorize loops if

it believes it is safe to do so.  The ``llvm.mem.parallel_loop_access`` metadata

which contains information about loop-carried memory dependencies can be helpful

in determining the safety of these transformations.



'``llvm.loop.vectorize.unroll``' Metadata

'``llvm.loop.interleave.count``' Metadata

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^



This metadata suggests an interleave count to the loop vectorizer.

The first operand is the string ``llvm.loop.vectorize.unroll`` and the

This metadata suggests an interleave count to the loop interleaver.

The first operand is the string ``llvm.loop.interleave.count`` and the

second operand is an integer specifying the interleave count. For

example:



.. code-block:: llvm



   !0 = metadata !{ metadata !"llvm.loop.vectorize.unroll", i32 4 }

   !0 = metadata !{ metadata !"llvm.loop.interleave.count", i32 4 }



Note that setting ``llvm.loop.interleave.count`` to 1 disables interleaving

multiple iterations of the loop.  If ``llvm.loop.interleave.count`` is set to 0

then the interleave count will be determined automatically.



'``llvm.loop.vectorize.enable``' Metadata

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^



This metadata selectively enables or disables vectorization for the loop. The

first operand is the string ``llvm.loop.vectorize.enable`` and the second operand

is a bit.  If the bit operand value is 1 vectorization is enabled. A value of

0 disables vectorization:



.. code-block:: llvm



Note that setting ``llvm.loop.vectorize.unroll`` to 1 disables

interleaving multiple iterations of the loop.  If

``llvm.loop.vectorize.unroll`` is set to 0 then the interleave count

will be determined automatically.

   !0 = metadata !{ metadata !"llvm.loop.vectorize.enable", i1 0 }

   !1 = metadata !{ metadata !"llvm.loop.vectorize.enable", i1 1 }



'``llvm.loop.vectorize.width``' Metadata

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

llvm/docs/ReleaseNotes.rst

+3 −1
Original line number Diff line number Diff line
@@ -57,7 +57,9 @@ Non-comprehensive list of changes in this release 
  unwinding information.



* The prefix for loop vectorizer hint metadata has been changed from

  ``llvm.vectorizer`` to ``llvm.loop.vectorize``.

  ``llvm.vectorizer`` to ``llvm.loop.vectorize``.  In addition,

  ``llvm.vectorizer.unroll`` metadata has been renamed

  ``llvm.loop.interleave.count``.



* Some backends previously implemented Atomic NAND(x,y) as ``x & ~y``. Now 

  all backends implement it as ``~(x & y)``, matching the semantics of GCC 4.4

llvm/lib/IR/AutoUpgrade.cpp

+4 −2
Original line number Diff line number Diff line
@@ -580,7 +580,9 @@ bool llvm::UpgradeDebugInfo(Module &M) { 


void llvm::UpgradeMDStringConstant(std::string &String) {

  const std::string OldPrefix = "llvm.vectorizer.";

  if (String.find(OldPrefix) == 0) {

  if (String == "llvm.vectorizer.unroll") {

    String = "llvm.loop.interleave.count";

  } else if (String.find(OldPrefix) == 0) {

    String.replace(0, OldPrefix.size(), "llvm.loop.vectorize.");

  }

}

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

+14 −12
Original line number Diff line number Diff line
@@ -978,8 +978,8 @@ public: 
          << "LV: Unrolling disabled by the pass manager\n");

  }



  /// Return the loop vectorizer metadata prefix.

  static StringRef Prefix() { return "llvm.loop.vectorize."; }

  /// Return the loop metadata prefix.

  static StringRef Prefix() { return "llvm.loop."; }



  MDNode *createHint(LLVMContext &Context, StringRef Name, unsigned V) const {

    SmallVector<Value*, 2> Vals;
@@ -1001,8 +1001,10 @@ public: 
      for (unsigned i = 1, ie = LoopID->getNumOperands(); i < ie; ++i)

        Vals.push_back(LoopID->getOperand(i));



    Vals.push_back(createHint(Context, Twine(Prefix(), "width").str(), Width));

    Vals.push_back(createHint(Context, Twine(Prefix(), "unroll").str(), 1));

    Vals.push_back(

        createHint(Context, Twine(Prefix(), "vectorize.width").str(), Width));

    Vals.push_back(

        createHint(Context, Twine(Prefix(), "interleave.count").str(), 1));



    MDNode *NewLoopID = MDNode::get(Context, Vals);

    // Set operand 0 to refer to the loop id itself.
@@ -1073,7 +1075,7 @@ private: 
      if (!S)

        continue;



      // Check if the hint starts with the vectorizer prefix.

      // Check if the hint starts with the loop metadata prefix.

      StringRef Hint = S->getString();

      if (!Hint.startswith(Prefix()))

        continue;
@@ -1091,22 +1093,22 @@ private: 
    if (!C) return;

    unsigned Val = C->getZExtValue();



    if (Hint == "width") {

    if (Hint == "vectorize.width") {

      if (isPowerOf2_32(Val) && Val <= MaxVectorWidth)

        Width = Val;

      else

        DEBUG(dbgs() << "LV: ignoring invalid width hint metadata\n");

    } else if (Hint == "unroll") {

      if (isPowerOf2_32(Val) && Val <= MaxUnrollFactor)

        Unroll = Val;

      else

        DEBUG(dbgs() << "LV: ignoring invalid unroll hint metadata\n");

    } else if (Hint == "enable") {

    } else if (Hint == "vectorize.enable") {

      if (C->getBitWidth() == 1)

        Force = Val == 1 ? LoopVectorizeHints::FK_Enabled

                         : LoopVectorizeHints::FK_Disabled;

      else

        DEBUG(dbgs() << "LV: ignoring invalid enable hint metadata\n");

    } else if (Hint == "interleave.count") {

      if (isPowerOf2_32(Val) && Val <= MaxUnrollFactor)

        Unroll = Val;

      else

        DEBUG(dbgs() << "LV: ignoring invalid unroll hint metadata\n");

    } else {

      DEBUG(dbgs() << "LV: ignoring unknown hint " << Hint << '\n');

    }

llvm/test/Assembler/upgrade-loop-metadata.ll

+1 −1
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ for.end: ; preds = %for.cond 
  ret void

}



; CHECK: !{metadata !"llvm.loop.vectorize.unroll", i32 4}

; CHECK: !{metadata !"llvm.loop.interleave.count", i32 4}

; CHECK: !{metadata !"llvm.loop.vectorize.width", i32 8}

; CHECK: !{metadata !"llvm.loop.vectorize.enable", i1 true}