[RISCV] Consolidate some DecoderNamespaces for standard extensions. (#128954)

First thing to know is that the subtarget feature checks used to block
accessing a decoder table are only a performance optimization and not
required for functionality. The tables have their own predicate checks.
I've removed them from all the standard extension tables.

-RV32 Zacas decoder namespace has been renamed to RV32GPRPair, I think
Zilsd(rv32 load/store pair) can go in here too.
-The RV32 Zdinx table has been renamed to also use RV32GPRPair.
-The Zfinx table has been renamed to remove superflous "RV" prefix.
-Zcmp and Zcmt tables have been combined into a ZcOverlap table. I think
 Zclsd(rv32 compressed load/store pair) can go in here too.
-All the extra standard extension tables are checked after the main
 standard extension table. This makes the common case of the main table
 matching occur earlier.
-Zicfiss is the exception to this as it needs to be checked before
 the main table since it overrides some encodings from Zcmop. This
can't be handled by a predicate based priority as Zicfiss only overrides
 a subset of Zcmop encodings.

Author: topperc

llvm/lib/Target/RISCV/Disassembler/RISCVDisassembler.cpp

@@ -657,16 +657,6 @@ DecodeStatus RISCVDisassembler::getInstruction32(MCInst &MI, uint64_t &Size,
 
   uint32_t Insn = support::endian::read32le(Bytes.data());
 
-  TRY_TO_DECODE(STI.hasFeature(RISCV::FeatureStdExtZdinx) &&
-                    !STI.hasFeature(RISCV::Feature64Bit),
-                DecoderTableRV32Zdinx32,
-                "RV32Zdinx (Double in Integer and rv32)");
-  TRY_TO_DECODE(STI.hasFeature(RISCV::FeatureStdExtZacas) &&
-                    !STI.hasFeature(RISCV::Feature64Bit),
-                DecoderTableRV32Zacas32,
-                "RV32Zacas (Compare-And-Swap and rv32)");
-  TRY_TO_DECODE_FEATURE(RISCV::FeatureStdExtZfinx, DecoderTableRVZfinx32,
-                        "RVZfinx (Float in Integer)");
   TRY_TO_DECODE_FEATURE(RISCV::FeatureVendorXVentanaCondOps,
                         DecoderTableXVentana32, "XVentanaCondOps");
   TRY_TO_DECODE_FEATURE(RISCV::FeatureVendorXTHeadBa, DecoderTableXTHeadBa32,
@@ -721,6 +711,11 @@ DecodeStatus RISCVDisassembler::getInstruction32(MCInst &MI, uint64_t &Size,
   TRY_TO_DECODE_FEATURE_ANY(XRivosFeatureGroup, DecoderTableXRivos32, "Rivos");
 
   TRY_TO_DECODE(true, DecoderTable32, "RISCV32");
+  TRY_TO_DECODE(true, DecoderTableRV32GPRPair32,
+                "RV32GPRPair (rv32 and GPR pairs)");
+  TRY_TO_DECODE(true, DecoderTableZfinx32, "Zfinx (Float in Integer)");
+  TRY_TO_DECODE(true, DecoderTableZdinxRV32GPRPair32,
+                "ZdinxRV32GPRPair (rv32 and Double in Integer)");
 
   return MCDisassembler::Fail;
 }
@@ -736,15 +731,6 @@ DecodeStatus RISCVDisassembler::getInstruction16(MCInst &MI, uint64_t &Size,
   Size = 2;
 
   uint32_t Insn = support::endian::read16le(Bytes.data());
-  TRY_TO_DECODE_AND_ADD_SP(!STI.hasFeature(RISCV::Feature64Bit),
-                           DecoderTableRISCV32Only_16,
-                           "RISCV32Only_16 (16-bit Instruction)");
-  TRY_TO_DECODE_FEATURE(RISCV::FeatureStdExtZicfiss, DecoderTableZicfiss16,
-                        "RVZicfiss (Shadow Stack)");
-  TRY_TO_DECODE_FEATURE(RISCV::FeatureStdExtZcmt, DecoderTableRVZcmt16,
-                        "Zcmt (16-bit Table Jump Instructions)");
-  TRY_TO_DECODE_FEATURE(RISCV::FeatureStdExtZcmp, DecoderTableRVZcmp16,
-                        "Zcmp (16-bit Push/Pop & Double Move Instructions)");
 
   TRY_TO_DECODE_FEATURE_ANY(XqciFeatureGroup, DecoderTableXqci16,
                             "Qualcomm uC 16bit");
@@ -753,8 +739,16 @@ DecodeStatus RISCVDisassembler::getInstruction16(MCInst &MI, uint64_t &Size,
       "Xqccmp (Qualcomm 16-bit Push/Pop & Double Move Instructions)");
   TRY_TO_DECODE_AND_ADD_SP(STI.hasFeature(RISCV::FeatureVendorXwchc),
                            DecoderTableXwchc16, "WCH QingKe XW");
+
+  // DecoderTableZicfiss16 must be checked before DecoderTable16.
+  TRY_TO_DECODE(true, DecoderTableZicfiss16, "RVZicfiss (Shadow Stack)");
   TRY_TO_DECODE_AND_ADD_SP(true, DecoderTable16,
                            "RISCV_C (16-bit Instruction)");
+  TRY_TO_DECODE_AND_ADD_SP(true, DecoderTableRISCV32Only_16,
+                           "RISCV32Only_16 (16-bit Instruction)");
+  // Zc* instructions incompatible with Zcf or Zcd.
+  TRY_TO_DECODE(true, DecoderTableZcOverlap16,
+                "ZcOverlap (16-bit Instructions overlapping with Zcf/Zcd)");
 
   return MCDisassembler::Fail;
 }

llvm/lib/Target/RISCV/RISCVInstrInfoD.td

@@ -60,9 +60,9 @@ def FPR64IN32X : RegisterOperand<GPRPair> {
 
 def DExt       : ExtInfo<"", "", [HasStdExtD], f64, FPR64, FPR32, FPR64, ?>;
 
-def ZdinxExt   : ExtInfo<"_INX", "RVZfinx", [HasStdExtZdinx, IsRV64],
+def ZdinxExt   : ExtInfo<"_INX", "Zfinx", [HasStdExtZdinx, IsRV64],
                          f64, FPR64INX, FPR32INX, FPR64INX, ?>;
-def Zdinx32Ext : ExtInfo<"_IN32X", "RV32Zdinx", [HasStdExtZdinx, IsRV32],
+def Zdinx32Ext : ExtInfo<"_IN32X", "ZdinxRV32GPRPair", [HasStdExtZdinx, IsRV32],
                          f64, FPR64IN32X, FPR32INX, FPR64IN32X, ?>;
 
 defvar DExts     = [DExt, ZdinxExt, Zdinx32Ext];

llvm/lib/Target/RISCV/RISCVInstrInfoF.td

@@ -116,7 +116,7 @@ class ExtInfo<string suffix, string space, list<Predicate> predicates,
 
 def FExt       : ExtInfo<"", "", [HasStdExtF], f32, FPR32, FPR32, ?, ?>;
 
-def ZfinxExt   : ExtInfo<"_INX", "RVZfinx", [HasStdExtZfinx], f32, FPR32INX, FPR32INX, ?, ?>;
+def ZfinxExt   : ExtInfo<"_INX", "Zfinx", [HasStdExtZfinx], f32, FPR32INX, FPR32INX, ?, ?>;
 
 defvar FExts   = [FExt, ZfinxExt];
 

llvm/lib/Target/RISCV/RISCVInstrInfoZa.td

@@ -59,7 +59,7 @@ let Predicates = [HasStdExtZacas], IsSignExtendingOpW = 1 in {
 defm AMOCAS_W : AMO_cas_aq_rl<0b00101, 0b010, "amocas.w", GPR>;
 } // Predicates = [HasStdExtZacas]
 
-let Predicates = [HasStdExtZacas, IsRV32], DecoderNamespace = "RV32Zacas"  in {
+let Predicates = [HasStdExtZacas, IsRV32], DecoderNamespace = "RV32GPRPair"  in {
 defm AMOCAS_D_RV32 : AMO_cas_aq_rl<0b00101, 0b011, "amocas.d", GPRPairRV32>;
 } // Predicates = [HasStdExtZacas, IsRV32]
 

llvm/lib/Target/RISCV/RISCVInstrInfoZc.td

@@ -216,7 +216,7 @@ def C_SH_INX : CStoreH_rri<0b100011, 0b0, "c.sh", GPRF16C>,
 } // Predicates = [HasStdExtZcb]
 
 // Zcmp
-let DecoderNamespace = "RVZcmp", Predicates = [HasStdExtZcmp],
+let DecoderNamespace = "ZcOverlap", Predicates = [HasStdExtZcmp],
     hasSideEffects = 0, mayLoad = 0, mayStore = 0 in {
 let Defs = [X10, X11] in
 def CM_MVA01S : RVInst16CA<0b101011, 0b11, 0b10, (outs),
@@ -227,9 +227,9 @@ let Uses = [X10, X11] in
 def CM_MVSA01 : RVInst16CA<0b101011, 0b01, 0b10, (outs SR07:$rs1, SR07:$rs2),
                             (ins), "cm.mvsa01", "$rs1, $rs2">,
                 Sched<[WriteIALU, WriteIALU, ReadIALU, ReadIALU]>;
-} // DecoderNamespace = "RVZcmp", Predicates = [HasStdExtZcmp]...
+} // DecoderNamespace = "ZcOverlap", Predicates = [HasStdExtZcmp]...
 
-let DecoderNamespace = "RVZcmp", Predicates = [HasStdExtZcmp] in {
+let DecoderNamespace = "ZcOverlap", Predicates = [HasStdExtZcmp] in {
 let hasSideEffects = 0, mayLoad = 0, mayStore = 1, Uses = [X2], Defs = [X2] in
 def CM_PUSH : RVInstZcCPPP<0b11000, "cm.push", negstackadj>,
               Sched<[WriteIALU, ReadIALU, ReadStoreData, ReadStoreData,
@@ -258,9 +258,9 @@ def CM_POP : RVInstZcCPPP<0b11010, "cm.pop">,
              Sched<[WriteIALU, WriteLDW, WriteLDW, WriteLDW, WriteLDW,
                     WriteLDW, WriteLDW, WriteLDW, WriteLDW, WriteLDW, WriteLDW,
                     WriteLDW, WriteLDW, WriteLDW, ReadIALU]>;
-} // DecoderNamespace = "RVZcmp", Predicates = [HasStdExtZcmp]...
+} // DecoderNamespace = "ZcOverlap", Predicates = [HasStdExtZcmp]...
 
-let DecoderNamespace = "RVZcmt", Predicates = [HasStdExtZcmt],
+let DecoderNamespace = "ZcOverlap", Predicates = [HasStdExtZcmt],
     hasSideEffects = 0, mayLoad = 0, mayStore = 0 in {
 def CM_JT : RVInst16CJ<0b101, 0b10, (outs), (ins uimm5:$index),
                        "cm.jt", "$index">{
@@ -278,7 +278,7 @@ def CM_JALT : RVInst16CJ<0b101, 0b10, (outs), (ins uimm8ge32:$index),
   let Inst{12-10} = 0b000;
   let Inst{9-2} = index;
 }
-} // DecoderNamespace = "RVZcmt", Predicates = [HasStdExtZcmt]...
+} // DecoderNamespace = "ZcOverlap", Predicates = [HasStdExtZcmt]...
 
 
 let Predicates = [HasStdExtZcb, HasStdExtZmmul] in{

llvm/lib/Target/RISCV/RISCVInstrInfoZfh.td

@@ -52,22 +52,22 @@ def ZfhDExt    : ExtInfo<"", "", [HasStdExtZfh, HasStdExtD],
 def ZfhminDExt : ExtInfo<"", "", [HasStdExtZfhmin, HasStdExtD],
                          ?, ?, FPR32, FPR64, FPR16>;
 
-def ZhinxExt            : ExtInfo<"_INX", "RVZfinx",
+def ZhinxExt            : ExtInfo<"_INX", "Zfinx",
                                   [HasStdExtZhinx],
                                   f16, FPR16INX, FPR32INX, ?, FPR16INX>;
-def ZhinxminExt         : ExtInfo<"_INX", "RVZfinx",
+def ZhinxminExt         : ExtInfo<"_INX", "Zfinx",
                                   [HasStdExtZhinxmin],
                                   f16, FPR16INX, FPR32INX, ?, FPR16INX>;
-def ZhinxZdinxExt       : ExtInfo<"_INX", "RVZfinx",
+def ZhinxZdinxExt       : ExtInfo<"_INX", "Zfinx",
                                   [HasStdExtZhinx, HasStdExtZdinx, IsRV64],
                                   ?, ?, FPR32INX, FPR64INX, FPR16INX>;
-def ZhinxminZdinxExt    : ExtInfo<"_INX", "RVZfinx",
+def ZhinxminZdinxExt    : ExtInfo<"_INX", "Zfinx",
                                   [HasStdExtZhinxmin, HasStdExtZdinx, IsRV64],
                                   ?, ?, FPR32INX, FPR64INX, FPR16INX>;
-def ZhinxZdinx32Ext     : ExtInfo<"_IN32X", "RV32Zdinx",
+def ZhinxZdinx32Ext     : ExtInfo<"_IN32X", "ZdinxGPRPairRV32",
                                   [HasStdExtZhinx, HasStdExtZdinx, IsRV32],
                                   ?, ?, FPR32INX, FPR64IN32X, FPR16INX >;
-def ZhinxminZdinx32Ext  : ExtInfo<"_IN32X", "RV32Zdinx",
+def ZhinxminZdinx32Ext  : ExtInfo<"_IN32X", "ZdinxGPRPairRV32",
                                   [HasStdExtZhinxmin, HasStdExtZdinx, IsRV32],
                                   ?, ?, FPR32INX, FPR64IN32X, FPR16INX>;