[Power9] Part-word VSX integer scalar loads/stores and sign extend instructions

This patch corresponds to review:
https://reviews.llvm.org/D23155

This patch removes the VSHRC register class (based on D20310) and adds
exploitation of the Power9 sub-word integer loads into VSX registers as well
as vector sign extensions.
The new instructions are useful for a few purposes:

    Int to Fp conversions of 1 or 2-byte values loaded from memory
    Building vectors of 1 or 2-byte integers with values loaded from memory
    Storing individual 1 or 2-byte elements from integer vectors

This patch implements all of those uses.

llvm-svn: 283190

1 files changed, 5 insertions, 13 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCVSXCopy.cpp b/llvm/lib/Target/PowerPC/PPCVSXCopy.cpp
index e4989e5687f..3b5d8f094fd 100644
--- a/llvm/lib/Target/PowerPC/PPCVSXCopy.cpp
+++ b/llvm/lib/Target/PowerPC/PPCVSXCopy.cpp
@@ -101,11 +101,8 @@ protected:
           // This is a copy *to* a VSX register from a non-VSX register.
           Changed = true;
 
-          const TargetRegisterClass *SrcRC =
-            IsVRReg(SrcMO.getReg(), MRI) ? &PPC::VSHRCRegClass :
-                                           &PPC::VSLRCRegClass;
+          const TargetRegisterClass *SrcRC = &PPC::VSLRCRegClass;
           assert((IsF8Reg(SrcMO.getReg(), MRI) ||
-                  IsVRReg(SrcMO.getReg(), MRI) ||
                   IsVSSReg(SrcMO.getReg(), MRI) ||
                   IsVSFReg(SrcMO.getReg(), MRI)) &&
                  "Unknown source for a VSX copy");
@@ -116,8 +113,7 @@ protected:
               .addImm(1) // add 1, not 0, because there is no implicit clearing
                          // of the high bits.
               .addOperand(SrcMO)
-              .addImm(IsVRReg(SrcMO.getReg(), MRI) ? PPC::sub_128
-                                                   : PPC::sub_64);
+              .addImm(PPC::sub_64);
 
           // The source of the original copy is now the new virtual register.
           SrcMO.setReg(NewVReg);
@@ -126,13 +122,10 @@ protected:
           // This is a copy *from* a VSX register to a non-VSX register.
           Changed = true;
 
-          const TargetRegisterClass *DstRC =
-            IsVRReg(DstMO.getReg(), MRI) ? &PPC::VSHRCRegClass :
-                                           &PPC::VSLRCRegClass;
+          const TargetRegisterClass *DstRC = &PPC::VSLRCRegClass;
           assert((IsF8Reg(DstMO.getReg(), MRI) ||
                   IsVSFReg(DstMO.getReg(), MRI) ||
-                  IsVSSReg(DstMO.getReg(), MRI) ||
-                  IsVRReg(DstMO.getReg(), MRI)) &&
+                  IsVSSReg(DstMO.getReg(), MRI)) &&
                  "Unknown destination for a VSX copy");
 
           // Copy the VSX value into a new VSX register of the correct subclass.
@@ -143,8 +136,7 @@ protected:
 
           // Transform the original copy into a subregister extraction copy.
           SrcMO.setReg(NewVReg);
-          SrcMO.setSubReg(IsVRReg(DstMO.getReg(), MRI) ? PPC::sub_128 :
-                                                         PPC::sub_64);
+          SrcMO.setSubReg(PPC::sub_64);
         }
       }