[AMDGPU][NFC] Extend PredicateControl to support True16 predicates. (#82245)

Using OtherPredicates for True16 predicates is often problematic due to
interference with other kinds of predicates, particularly when this
overrides predicates inherited from pseudo instructions.

Author: kosarev

llvm/lib/Target/AMDGPU/AMDGPU.td

@@ -9,6 +9,7 @@
 include "llvm/TableGen/SearchableTable.td"
 include "llvm/Target/Target.td"
 include "AMDGPUFeatures.td"
+include "AMDGPUPredicateControl.td"
 
 def p0 : PtrValueType<i64, 0>;
 def p1 : PtrValueType<i64, 1>;
@@ -1895,10 +1896,10 @@ def NotHasTrue16BitInsts : Predicate<"!Subtarget->hasTrue16BitInsts()">;
 // True16 instructions as they are defined in the ISA. Fake True16
 // instructions have the same encoding as real ones but syntactically
 // only allow 32-bit registers in operands and use low halves thereof.
-def UseRealTrue16Insts : Predicate<"Subtarget->useRealTrue16Insts()">,
+def UseRealTrue16Insts : True16PredicateClass<"Subtarget->useRealTrue16Insts()">,
   AssemblerPredicate<(all_of FeatureTrue16BitInsts, FeatureRealTrue16Insts)>;
-def UseFakeTrue16Insts : Predicate<"Subtarget->hasTrue16BitInsts() && "
-                                   "!Subtarget->useRealTrue16Insts()">;
+def UseFakeTrue16Insts : True16PredicateClass<"Subtarget->hasTrue16BitInsts() && "
+                                              "!Subtarget->useRealTrue16Insts()">;
 
 def HasVOP3PInsts : Predicate<"Subtarget->hasVOP3PInsts()">,
   AssemblerPredicate<(all_of FeatureVOP3P)>;

llvm/lib/Target/AMDGPU/AMDGPUInstructions.td

@@ -76,33 +76,11 @@ class ILFormat<dag outs, dag ins, string asmstr, list<dag> pattern>
      let isCodeGenOnly = 1;
 }
 
-def TruePredicate : Predicate<"">;
-
-// FIXME: Tablegen should specially supports this
-def FalsePredicate : Predicate<"false">;
-
-// Add a predicate to the list if does not already exist to deduplicate it.
-class PredConcat<list<Predicate> lst, Predicate pred> {
-  list<Predicate> ret = !listconcat(lst, !listremove([pred], lst));
-}
-
 // Get the union of two Register lists
 class RegListUnion<list<Register> lstA, list<Register> lstB> {
   list<Register> ret = !listconcat(lstA, !listremove(lstB, lstA));
 }
 
-class PredicateControl {
-  Predicate SubtargetPredicate = TruePredicate;
-  Predicate AssemblerPredicate = TruePredicate;
-  Predicate WaveSizePredicate = TruePredicate;
-  list<Predicate> OtherPredicates = [];
-  list<Predicate> Predicates = PredConcat<
-                                 PredConcat<PredConcat<OtherPredicates,
-                                                       SubtargetPredicate>.ret,
-                                            AssemblerPredicate>.ret,
-                                 WaveSizePredicate>.ret;
-}
-
 class AMDGPUPat<dag pattern, dag result> : Pat<pattern, result>,
       PredicateControl, GISelFlags;
 

llvm/lib/Target/AMDGPU/AMDGPUPredicateControl.td

@@ -0,0 +1,36 @@
+//===-- AMDGPUPredicateControl.td --------------------------*- tablegen -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+def TruePredicate : Predicate<"">;
+
+// FIXME: Tablegen should specially supports this
+def FalsePredicate : Predicate<"false">;
+
+// Add a predicate to the list if does not already exist to deduplicate it.
+class PredConcat<Predicate pred, list<Predicate> lst> {
+  list<Predicate> ret = !listconcat(lst, !listremove([pred], lst));
+}
+
+// Prevent using other kinds of predicates where True16 predicates are
+// expected by giving them their own class.
+class True16PredicateClass<string cond> : Predicate<cond>;
+def NoTrue16Predicate : True16PredicateClass<"">;
+
+class PredicateControl {
+  Predicate SubtargetPredicate = TruePredicate;
+  Predicate AssemblerPredicate = TruePredicate;
+  Predicate WaveSizePredicate = TruePredicate;
+  True16PredicateClass True16Predicate = NoTrue16Predicate;
+  list<Predicate> OtherPredicates = [];
+  list<Predicate> Predicates =
+      PredConcat<SubtargetPredicate,
+      PredConcat<AssemblerPredicate,
+      PredConcat<WaveSizePredicate,
+      PredConcat<True16Predicate,
+      OtherPredicates>.ret>.ret>.ret>.ret;
+}

llvm/lib/Target/AMDGPU/R600.td

@@ -35,6 +35,7 @@ include "R600Schedule.td"
 include "R600Processors.td"
 include "R600InstrInfo.td"
 include "AMDGPUInstrInfo.td"
+include "AMDGPUPredicateControl.td"
 include "AMDGPUInstructions.td"
 include "R600Instructions.td"
 include "R700Instructions.td"

llvm/lib/Target/AMDGPU/VOPInstructions.td

@@ -1484,8 +1484,8 @@ multiclass VOP3_Real_dpp8_with_name<GFXGen Gen, bits<10> op, string opName,
   let AsmString = asmName # ps.Pfl.AsmVOP3DPP8,
       DecoderNamespace = "DPP8"#Gen.DecoderNamespace#
                          !if(ps.Pfl.IsRealTrue16, "", "_FAKE16"),
-      OtherPredicates = !if(ps.Pfl.IsRealTrue16, [UseRealTrue16Insts],
-                            [TruePredicate]) in {
+      True16Predicate = !if(ps.Pfl.IsRealTrue16, UseRealTrue16Insts,
+                            NoTrue16Predicate) in {
     defm NAME : VOP3_Real_dpp8_Base<Gen, op, opName>;
   }
 }