[mips][msa] Remove the VSPLAT and VSPLATD nodes in favour of matching BUILD_VECTOR.

Most constant BUILD_VECTOR's are matched using ComplexPatterns which cover
bitcasted as well as normal vectors. However, it doesn't seem to be possible to
match ldi.[bhwd] in a type-agnostic manner (e.g. to support the widest range of
immediates, it should be possible to use ldi.b to load v2i64) using TableGen so
ldi.[bhwd] is matched using custom code in MipsSEISelDAGToDAG.cpp

This made the majority of the constant splat BUILD_VECTOR lowering redundant.
The only transformation remaining for constant splats is when an (up-to) 32-bit
constant splat is possible but the value does not fit into a 10-bit signed
integer. In this case, the BUILD_VECTOR is transformed into a bitcasted
BUILD_VECTOR so that fill.[bhw] can be used to splat the vector from a GPR32
register (which is initialized using the usual lui/addui sequence).

There are no additional tests since this is a re-implementation of previous
functionality. The change is intended to make it easier to implement some of
the upcoming instruction selection patches since they can rely on existing
support for BUILD_VECTOR's in the DAGCombiner.

compare_float.ll changed slightly because a BITCAST is no longer
introduced during legalization.

llvm-svn: 191299

1 files changed, 17 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsISelDAGToDAG.h b/llvm/lib/Target/Mips/MipsISelDAGToDAG.h
index e98d590a279..208701e346c 100644
--- a/llvm/lib/Target/Mips/MipsISelDAGToDAG.h
+++ b/llvm/lib/Target/Mips/MipsISelDAGToDAG.h
@@ -76,6 +76,23 @@ private:
   virtual bool selectAddr16(SDNode *Parent, SDValue N, SDValue &Base,
                             SDValue &Offset, SDValue &Alias);
 
+  /// \brief Select constant vector splats.
+  virtual bool selectVSplat(SDNode *N, APInt &Imm) const;
+  /// \brief Select constant vector splats whose value fits in a uimm3.
+  virtual bool selectVSplatUimm3(SDValue N, SDValue &Imm) const;
+  /// \brief Select constant vector splats whose value fits in a uimm4.
+  virtual bool selectVSplatUimm4(SDValue N, SDValue &Imm) const;
+  /// \brief Select constant vector splats whose value fits in a uimm5.
+  virtual bool selectVSplatUimm5(SDValue N, SDValue &Imm) const;
+  /// \brief Select constant vector splats whose value fits in a uimm6.
+  virtual bool selectVSplatUimm6(SDValue N, SDValue &Imm) const;
+  /// \brief Select constant vector splats whose value fits in a uimm8.
+  virtual bool selectVSplatUimm8(SDValue N, SDValue &Imm) const;
+  /// \brief Select constant vector splats whose value fits in a simm5.
+  virtual bool selectVSplatSimm5(SDValue N, SDValue &Imm) const;
+  /// \brief Select constant vector splats whose value is a power of 2.
+  virtual bool selectVSplatUimmPow2(SDValue N, SDValue &Imm) const;
+
   virtual SDNode *Select(SDNode *N);
 
   virtual std::pair<bool, SDNode*> selectNode(SDNode *Node) = 0;