AMDGPU: Fix scheduiling info for spill pseudos

[arsenm]

Summary

These defaulted to Write32Bit. I don't think this actually matters
since these don't exist during scheduling.

[• tstellarAMD]

LGTM.

[arsenm]

r281127

lib/Target/AMDGPU/SIInstructions.td

 // SI_SPILL_32_* instructions.
 defm SI_SPILL_S32  : SI_SPILL_SGPR <SReg_32>;
 defm SI_SPILL_S64  : SI_SPILL_SGPR <SReg_64>;
 defm SI_SPILL_S128 : SI_SPILL_SGPR <SReg_128>;
 defm SI_SPILL_S256 : SI_SPILL_SGPR <SReg_256>;
 defm SI_SPILL_S512 : SI_SPILL_SGPR <SReg_512>;
 
 multiclass SI_SPILL_VGPR <RegisterClass vgpr_class> {
-  let UseNamedOperandTable = 1, VGPRSpill = 1 in {
+  let UseNamedOperandTable = 1, VGPRSpill = 1,
+       SchedRW = [WriteVMEM] in {
     def _SAVE : VPseudoInstSI <
       (outs),
       (ins vgpr_class:$vdata, i32imm:$vaddr, SReg_128:$scratch_rsrc,
            SReg_32:$scratch_offset, i32imm:$offset)> {
       let mayStore = 1;
       let mayLoad = 0;
       // (2 * 4) + (8 * num_subregs) bytes maximum
       let Size = !add(!shl(!srl(vgpr_class.Size, 5), 3), 8);
     }
 
     def _RESTORE : VPseudoInstSI <
       (outs vgpr_class:$vdata),
       (ins i32imm:$vaddr, SReg_128:$scratch_rsrc, SReg_32:$scratch_offset,
            i32imm:$offset)> {
       let mayStore = 0;
       let mayLoad = 1;
 
       // (2 * 4) + (8 * num_subregs) bytes maximum
       let Size = !add(!shl(!srl(vgpr_class.Size, 5), 3), 8);
     }
-  } // End UseNamedOperandTable = 1, VGPRSpill = 1
+  } // End UseNamedOperandTable = 1, VGPRSpill = 1, SchedRW = [WriteVMEM]
 }
 
 defm SI_SPILL_V32  : SI_SPILL_VGPR <VGPR_32>;
 defm SI_SPILL_V64  : SI_SPILL_VGPR <VReg_64>;
 defm SI_SPILL_V96  : SI_SPILL_VGPR <VReg_96>;
 defm SI_SPILL_V128 : SI_SPILL_VGPR <VReg_128>;
 defm SI_SPILL_V256 : SI_SPILL_VGPR <VReg_256>;
 defm SI_SPILL_V512 : SI_SPILL_VGPR <VReg_512>;