AMDGPU: Use default operands for clamp/omod

[arsenm]

Summary

We have a lot of complex pattern variants that just set the source
modifiers that are really handled, and then set the output modifiers
to 0. We're unlikely to ever match output modifiers from the use
instruction side, and we already match clamp/omod in a separate pass.

[rampitec]

LGTM

[arsenm]

e93b1ffc8490d943690726370a0e9277fd78520d

lib/Target/AMDGPU/SIInstrInfo.td

class NamedMatchClass<string CName, bit Optional = 1> : AsmOperandClass {
   let DefaultMethod = !if(Optional, "default"#CName, ?);
 }
 
 class NamedOperandBit<string Name, AsmOperandClass MatchClass> : Operand<i1> {
   let PrintMethod = "print"#Name;
   let ParserMatchClass = MatchClass;
 }
 
+class NamedOperandBit_0<string Name, AsmOperandClass MatchClass> :
+  OperandWithDefaultOps<i1, (ops (i1 0))> {
+  let PrintMethod = "print"#Name;
+  let ParserMatchClass = MatchClass;
+}
+
 class NamedOperandU8<string Name, AsmOperandClass MatchClass> : Operand<i8> {
   let PrintMethod = "print"#Name;
   let ParserMatchClass = MatchClass;
 }
 
 class NamedOperandU16<string Name, AsmOperandClass MatchClass> : Operand<i16> {
   let PrintMethod = "print"#Name;
   let ParserMatchClass = MatchClass;
 }
 
 class NamedOperandU32<string Name, AsmOperandClass MatchClass> : Operand<i32> {
   let PrintMethod = "print"#Name;
   let ParserMatchClass = MatchClass;
 }
 
+class NamedOperandU32_0<string Name, AsmOperandClass MatchClass> :
+  OperandWithDefaultOps<i32, (ops (i32 0))> {
+  let PrintMethod = "print"#Name;
+  let ParserMatchClass = MatchClass;
+}
+
 class NamedOperandU32Default0<string Name, AsmOperandClass MatchClass> :
   OperandWithDefaultOps<i32, (ops (i32 0))> {
   let PrintMethod = "print"#Name;
   let ParserMatchClass = MatchClass;
 }
 
 let OperandType = "OPERAND_IMMEDIATE" in {
 
 def offen : NamedOperandBit<"Offen", NamedMatchClass<"Offen">>;
 def idxen : NamedOperandBit<"Idxen", NamedMatchClass<"Idxen">>;
 def addr64 : NamedOperandBit<"Addr64", NamedMatchClass<"Addr64">>;
 
 def flat_offset : NamedOperandU16<"FlatOffset", NamedMatchClass<"FlatOffset">>;
 def offset : NamedOperandU16<"Offset", NamedMatchClass<"Offset">>;
 def offset0 : NamedOperandU8<"Offset0", NamedMatchClass<"Offset0">>;
 def offset1 : NamedOperandU8<"Offset1", NamedMatchClass<"Offset1">>;
 
 def gds : NamedOperandBit<"GDS", NamedMatchClass<"GDS">>;
 
 def omod : NamedOperandU32<"OModSI", NamedMatchClass<"OModSI">>;
+def omod0 : NamedOperandU32_0<"OModSI", NamedMatchClass<"OModSI">>;
+
+// We need to make the cases with a default of 0 distinct from no
+// default to help deal with some cases where the operand appears
+// before a mandatory operand.
 def clampmod : NamedOperandBit<"ClampSI", NamedMatchClass<"ClampSI">>;
+def clampmod0 : NamedOperandBit_0<"ClampSI", NamedMatchClass<"ClampSI">>;
 def highmod : NamedOperandBit<"High", NamedMatchClass<"High">>;
 
 def DLC : NamedOperandBit<"DLC", NamedMatchClass<"DLC">>;
 def GLC : NamedOperandBit<"GLC", NamedMatchClass<"GLC">>;
 def SLC : NamedOperandBit<"SLC", NamedMatchClass<"SLC">>;
 def TFE : NamedOperandBit<"TFE", NamedMatchClass<"TFE">>;
 def SWZ : NamedOperandBit<"SWZ", NamedMatchClass<"SWZ">>;
 def UNorm : NamedOperandBit<"UNorm", NamedMatchClass<"UNorm">>;
dag ret =
     !if (!eq(NumSrcArgs, 0),
       // VOP1 without input operands (V_NOP, V_CLREXCP)
       (ins),
       /* else */
     !if (!eq(NumSrcArgs, 1),
       !if (!eq(HasModifiers, 1),
         // VOP1 with modifiers
         (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
-             clampmod:$clamp, omod:$omod)
+             clampmod0:$clamp, omod0:$omod)
       /* else */,
         // VOP1 without modifiers
         !if (!eq(HasIntClamp, 1),
-          (ins Src0RC:$src0, clampmod:$clamp),
+          (ins Src0RC:$src0, clampmod0:$clamp),
           (ins Src0RC:$src0))
       /* endif */ ),
     !if (!eq(NumSrcArgs, 2),
       !if (!eq(HasModifiers, 1),
         // VOP 2 with modifiers
         !if( !eq(HasOMod, 1),
           (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                Src1Mod:$src1_modifiers, Src1RC:$src1,
-               clampmod:$clamp, omod:$omod),
+               clampmod0:$clamp, omod0:$omod),
            (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                Src1Mod:$src1_modifiers, Src1RC:$src1,
-               clampmod:$clamp))
+               clampmod0:$clamp))
       /* else */,
         // VOP2 without modifiers
         !if (!eq(HasIntClamp, 1),
-          (ins Src0RC:$src0, Src1RC:$src1, clampmod:$clamp),
+          (ins Src0RC:$src0, Src1RC:$src1, clampmod0:$clamp),
           (ins Src0RC:$src0, Src1RC:$src1))
 
       /* endif */ )
     /* NumSrcArgs == 3 */,
       !if (!eq(HasModifiers, 1),
         !if (!eq(HasSrc2Mods, 1),
           // VOP3 with modifiers
           !if (!eq(HasOMod, 1),
             (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                  Src1Mod:$src1_modifiers, Src1RC:$src1,
                  Src2Mod:$src2_modifiers, Src2RC:$src2,
-                 clampmod:$clamp, omod:$omod),
+                 clampmod0:$clamp, omod0:$omod),
             !if (!eq(HasIntClamp, 1),
               (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                    Src1Mod:$src1_modifiers, Src1RC:$src1,
                    Src2Mod:$src2_modifiers, Src2RC:$src2,
-                   clampmod:$clamp),
+                   clampmod0:$clamp),
               (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                    Src1Mod:$src1_modifiers, Src1RC:$src1,
                    Src2Mod:$src2_modifiers, Src2RC:$src2))),
           // VOP3 with modifiers except src2
           !if (!eq(HasOMod, 1),
             (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                  Src1Mod:$src1_modifiers, Src1RC:$src1,
-                 Src2RC:$src2, clampmod:$clamp, omod:$omod),
+                 Src2RC:$src2, clampmod0:$clamp, omod0:$omod),
             !if (!eq(HasIntClamp, 1),
               (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                    Src1Mod:$src1_modifiers, Src1RC:$src1,
-                   Src2RC:$src2, clampmod:$clamp),
+                   Src2RC:$src2, clampmod0:$clamp),
               (ins Src0Mod:$src0_modifiers, Src0RC:$src0,
                    Src1Mod:$src1_modifiers, Src1RC:$src1,
                    Src2RC:$src2))))
       /* else */,
         // VOP3 without modifiers
         !if (!eq(HasIntClamp, 1),
-          (ins Src0RC:$src0, Src1RC:$src1, Src2RC:$src2, clampmod:$clamp),
+          (ins Src0RC:$src0, Src1RC:$src1, Src2RC:$src2, clampmod0:$clamp),
           (ins Src0RC:$src0, Src1RC:$src1, Src2RC:$src2))
       /* endif */ ))));
 }
 
 /// XXX - src1 may only allow VGPRs?
 
 // The modifiers (except clamp) are dummy operands for the benefit of
 // printing and parsing. They defer their values to looking at the