[PowerPC] custom lower `v2f64 fpext v2f32`

Reduces scalarization overhead via custom lowering of v2f64 fpext v2f32.

eg. For the following IR
  %0 = load <2 x float>, <2 x float>* %Ptr, align 8
  %1 = fpext <2 x float> %0 to <2 x double>
  ret <2 x double> %1

Pre custom lowering:
  ld r3, 0(r3)
  mtvsrd f0, r3
  xxswapd vs34, vs0
  xscvspdpn f0, vs0
  xxsldwi vs1, vs34, vs34, 3
  xscvspdpn f1, vs1
  xxmrghd vs34, vs0, vs1

After custom lowering:
  lfd f0, 0(r3)
  xxmrghw vs0, vs0, vs0
  xvcvspdp vs34, vs0

Differential Revision: https://reviews.llvm.org/D57857

llvm-svn: 360429

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index 208306c577e..cf812a25085 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -404,6 +404,9 @@ namespace llvm {
       /// representation.
       QBFLT,
 
+      /// Custom extend v4f32 to v2f64.
+      FP_EXTEND_LH,
+
       /// CHAIN = STBRX CHAIN, GPRC, Ptr, Type - This is a
       /// byte-swapping store instruction.  It byte-swaps the low "Type" bits of
       /// the GPRC input, then stores it through Ptr.  Type can be either i16 or
@@ -445,6 +448,10 @@ namespace llvm {
       /// an xxswapd.
       LXVD2X,
 
+      /// VSRC, CHAIN = LD_VSX_LH CHAIN, Ptr - This is a floating-point load of a
+      /// v2f32 value into the lower half of a VSR register.
+      LD_VSX_LH,
+
       /// CHAIN = STXVD2X CHAIN, VSRC, Ptr - Occurs only for little endian.
       /// Maps directly to an stxvd2x instruction that will be preceded by
       /// an xxswapd.
@@ -1021,6 +1028,7 @@ namespace llvm {
     SDValue LowerSIGN_EXTEND_INREG(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerMUL(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerABS(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerFP_EXTEND(SDValue Op, SelectionDAG &DAG) const;
 
     SDValue LowerVectorLoad(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerVectorStore(SDValue Op, SelectionDAG &DAG) const;