AMDGPU: Use HasFP8ConversionInsts appropriately, NFC (#82433)

The corresponding fp8 conversion instructions are available for a
subtarget when and only when the subtarget "HasFP8ConversionInsts". We
should not assume all the future subtargets (gfx12+) have
FP8ConversionInsts.
  In this patch, we use OtherPredicates to carry HasFP8ConversionInsts
feature. This is because SubtargetPredicate is not copied from pseudos
to reals for DPP16 and DPP6. To avoid overriding OtherPredicates in a
few places, we use the newly introduced True16Predicate to hold
UseRealTrue16Insts instead.
 This work repalces the inadvertently closed pull request:
#82024

Author: changpeng

llvm/lib/Target/AMDGPU/VOP1Instructions.td

@@ -1,3 +1,4 @@
+
 //===-- VOP1Instructions.td - Vector Instruction Definitions --------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
@@ -565,7 +566,7 @@ class VOPProfile_Base_CVT_F32_F8<ValueType vt> : VOPProfileI2F <vt, i32> {
 def VOPProfileCVT_F32_F8    : VOPProfile_Base_CVT_F32_F8 <f32>;
 def VOPProfileCVT_PK_F32_F8 : VOPProfile_Base_CVT_F32_F8 <v2f32>;
 
-let SubtargetPredicate = HasFP8ConversionInsts, mayRaiseFPException = 0,
+let OtherPredicates = [HasFP8ConversionInsts], mayRaiseFPException = 0,
     SchedRW = [WriteFloatCvt] in {
   defm V_CVT_F32_FP8    : VOP1Inst<"v_cvt_f32_fp8", VOPProfileCVT_F32_F8>;
   defm V_CVT_F32_BF8    : VOP1Inst<"v_cvt_f32_bf8", VOPProfileCVT_F32_F8>;
@@ -653,7 +654,7 @@ class Cvt_F32_F8_Pat_OpSel<SDPatternOperator node, bits<2> index,
          (inst_e32 $src))
 >;
 
-let SubtargetPredicate = isGFX12Plus in {
+let SubtargetPredicate = isGFX12Plus, OtherPredicates = [HasFP8ConversionInsts] in {
   foreach Index = [0, 1, 2, 3] in {
     def : Cvt_F32_F8_Pat_OpSel<int_amdgcn_cvt_f32_fp8, Index,
                                V_CVT_F32_FP8_e32, V_CVT_F32_FP8_OP_SEL_e64>;
@@ -670,7 +671,7 @@ class Cvt_PK_F32_F8_Pat_OpSel<SDPatternOperator node, int index,
          (inst_e32 $src))
 >;
 
-let SubtargetPredicate = isGFX12Plus in {
+let SubtargetPredicate = isGFX12Plus, OtherPredicates = [HasFP8ConversionInsts] in {
   foreach Index = [0, -1] in {
     def : Cvt_PK_F32_F8_Pat_OpSel<int_amdgcn_cvt_pk_f32_fp8, Index,
                                   V_CVT_PK_F32_FP8_e32, V_CVT_PK_F32_FP8_OP_SEL_e64>;

llvm/lib/Target/AMDGPU/VOP3Instructions.td

@@ -640,7 +640,7 @@ defm V_LSHL_OR_B32 : VOP3Inst <"v_lshl_or_b32", VOP3_Profile<VOP_I32_I32_I32_I32
 let SubtargetPredicate = isGFX940Plus in
 defm V_LSHL_ADD_U64 : VOP3Inst <"v_lshl_add_u64", VOP3_Profile<VOP_I64_I64_I32_I64>>;
 
-let SubtargetPredicate = HasFP8ConversionInsts, mayRaiseFPException = 0,
+let OtherPredicates = [HasFP8ConversionInsts], mayRaiseFPException = 0,
     SchedRW = [WriteFloatCvt] in {
   let Constraints = "$vdst = $vdst_in", DisableEncoding = "$vdst_in" in {
     defm V_CVT_PK_FP8_F32 : VOP3Inst<"v_cvt_pk_fp8_f32", VOP3_CVT_PK_F8_F32_Profile>;
@@ -667,6 +667,7 @@ class Cvt_SR_F8_F32_Pat<SDPatternOperator node, bits<2> index, VOP3_Pseudo inst>
           !if(index{0}, SRCMODS.OP_SEL_0, 0), $old, 0)
 >;
 
+let OtherPredicates = [HasFP8ConversionInsts] in {
 foreach Index = [0, -1] in {
   def : Cvt_PK_F8_F32_Pat<int_amdgcn_cvt_pk_fp8_f32, Index, V_CVT_PK_FP8_F32_e64>;
   def : Cvt_PK_F8_F32_Pat<int_amdgcn_cvt_pk_bf8_f32, Index, V_CVT_PK_BF8_F32_e64>;
@@ -676,6 +677,7 @@ foreach Index = [0, 1, 2, 3] in {
   def : Cvt_SR_F8_F32_Pat<int_amdgcn_cvt_sr_fp8_f32, Index, V_CVT_SR_FP8_F32_e64>;
   def : Cvt_SR_F8_F32_Pat<int_amdgcn_cvt_sr_bf8_f32, Index, V_CVT_SR_BF8_F32_e64>;
 }
+}
 
 class ThreeOp_i32_Pats <SDPatternOperator op1, SDPatternOperator op2, Instruction inst> : GCNPat <
   // This matches (op2 (op1 i32:$src0, i32:$src1), i32:$src2) with conditions.

llvm/lib/Target/AMDGPU/VOPInstructions.td

@@ -210,7 +210,7 @@ class VOP3_Real <VOP_Pseudo ps, int EncodingFamily, string asm_name = ps.Mnemoni
 class VOP3_Real_Gen <VOP_Pseudo ps, GFXGen Gen, string asm_name = ps.Mnemonic> :
   VOP3_Real <ps, Gen.Subtarget, asm_name> {
   let AssemblerPredicate = Gen.AssemblerPredicate;
-  let OtherPredicates = !if(ps.Pfl.IsRealTrue16, [UseRealTrue16Insts], []);
+  let True16Predicate = !if(ps.Pfl.IsRealTrue16, UseRealTrue16Insts, NoTrue16Predicate);
   let DecoderNamespace = Gen.DecoderNamespace#
                          !if(ps.Pfl.IsRealTrue16, "", "_FAKE16");
 }
@@ -1349,7 +1349,7 @@ class VOP3_DPP16_Gen<bits<10> op, VOP_DPP_Pseudo ps, GFXGen Gen,
                      string opName = ps.OpName> :
   VOP3_DPP16 <op, ps, Gen.Subtarget, opName> {
   let AssemblerPredicate = Gen.AssemblerPredicate;
-  let OtherPredicates = !if(ps.Pfl.IsRealTrue16, [UseRealTrue16Insts], []);
+  let True16Predicate = !if(ps.Pfl.IsRealTrue16, UseRealTrue16Insts, NoTrue16Predicate);
   let DecoderNamespace = "DPP"#Gen.DecoderNamespace#
                          !if(ps.Pfl.IsRealTrue16, "", "_FAKE16");
 }