[RISCV] Zabha/Zacas implies Zaamo (llvm#115694)

The Zabha/Zacas extension depends upon the Zaamo extension. 
Ref: https://github.com/riscv/riscv-isa-manual/blob/main/src/zacas.adoc
https://github.com/riscv/riscv-isa-manual/blob/main/src/zabha.adoc.

Author: tclin914

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -237,14 +237,16 @@ def HasStdExtAOrZaamo
 
 def FeatureStdExtZabha
     : RISCVExtension<"zabha", 1, 0,
-                     "'Zabha' (Byte and Halfword Atomic Memory Operations)">;
+                     "'Zabha' (Byte and Halfword Atomic Memory Operations)",
+                     [FeatureStdExtZaamo]>;
 def HasStdExtZabha : Predicate<"Subtarget->hasStdExtZabha()">,
                      AssemblerPredicate<(all_of FeatureStdExtZabha),
                          "'Zabha' (Byte and Halfword Atomic Memory Operations)">;
 
 def FeatureStdExtZacas
     : RISCVExtension<"zacas", 1, 0,
-                     "'Zacas' (Atomic Compare-And-Swap Instructions)">,
+                     "'Zacas' (Atomic Compare-And-Swap Instructions)",
+                     [FeatureStdExtZaamo]>,
       RISCVExtensionBitmask<0, 26>;
 def HasStdExtZacas : Predicate<"Subtarget->hasStdExtZacas()">,
                      AssemblerPredicate<(all_of FeatureStdExtZacas),

llvm/lib/TargetParser/RISCVISAInfo.cpp

@@ -760,11 +760,6 @@ Error RISCVISAInfo::checkDependency() {
   if (XLen != 32 && Exts.count("zcf"))
     return getError("'zcf' is only supported for 'rv32'");
 
-  if (!(Exts.count("a") || Exts.count("zaamo")))
-    for (auto Ext : {"zacas", "zabha"})
-      if (Exts.count(Ext))
-        return getExtensionRequiresError(Ext, "a' or 'zaamo");
-
   if (Exts.count("xwchc") != 0) {
     if (XLen != 32)
       return getError("'xwchc' is only supported for 'rv32'");

llvm/test/CodeGen/RISCV/attributes.ll

@@ -428,11 +428,11 @@
 ; RV32ZFBFMIN: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zfbfmin1p0"
 ; RV32ZVFBFMIN: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvl32b1p0"
 ; RV32ZVFBFWMA: .attribute 5, "rv32i2p1_f2p2_zicsr2p0_zfbfmin1p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvfbfwma1p0_zvl32b1p0"
-; RV32ZACAS: .attribute 5, "rv32i2p1_a2p1_zacas1p0"
+; RV32ZACAS: .attribute 5, "rv32i2p1_a2p1_zaamo1p0_zacas1p0"
 ; RV32ZALASR: .attribute 5, "rv32i2p1_zalasr0p1"
 ; RV32ZAMA16B: .attribute 5, "rv32i2p1_zama16b1p0"
 ; RV32ZICFILP: .attribute 5, "rv32i2p1_zicfilp1p0_zicsr2p0"
-; RV32ZABHA: .attribute 5, "rv32i2p1_a2p1_zabha1p0"
+; RV32ZABHA: .attribute 5, "rv32i2p1_a2p1_zaamo1p0_zabha1p0"
 ; RV32ZVBC32E: .attribute 5, "rv32i2p1_zicsr2p0_zvbc32e0p7_zve32x1p0_zvl32b1p0"
 ; RV32ZVKGS: .attribute 5, "rv32i2p1_zicsr2p0_zve32x1p0_zvkg1p0_zvkgs0p7_zvl32b1p0"
 ; RV32SSNPM: .attribute 5, "rv32i2p1_ssnpm1p0"
@@ -574,10 +574,10 @@
 ; RV64ZFBFMIN: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zfbfmin1p0"
 ; RV64ZVFBFMIN: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvl32b1p0"
 ; RV64ZVFBFWMA: .attribute 5, "rv64i2p1_f2p2_zicsr2p0_zfbfmin1p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvfbfwma1p0_zvl32b1p0"
-; RV64ZACAS: .attribute 5, "rv64i2p1_a2p1_zacas1p0"
+; RV64ZACAS: .attribute 5, "rv64i2p1_a2p1_zaamo1p0_zacas1p0"
 ; RV64ZALASR: .attribute 5, "rv64i2p1_zalasr0p1"
 ; RV64ZICFILP: .attribute 5, "rv64i2p1_zicfilp1p0_zicsr2p0"
-; RV64ZABHA: .attribute 5, "rv64i2p1_a2p1_zabha1p0"
+; RV64ZABHA: .attribute 5, "rv64i2p1_a2p1_zaamo1p0_zabha1p0"
 ; RV64ZVBC32E: .attribute 5, "rv64i2p1_zicsr2p0_zvbc32e0p7_zve32x1p0_zvl32b1p0"
 ; RV64ZVKGS: .attribute 5, "rv64i2p1_zicsr2p0_zve32x1p0_zvkg1p0_zvkgs0p7_zvl32b1p0"
 ; RV64SSNPM: .attribute 5, "rv64i2p1_ssnpm1p0"

llvm/test/MC/RISCV/attribute-arch.s

@@ -394,7 +394,7 @@
 # CHECK: .attribute     5, "rv32i2p1_f2p2_zicsr2p0_zfbfmin1p0_zve32f1p0_zve32x1p0_zvfbfmin1p0_zvfbfwma1p0_zvl32b1p0"
 
 .attribute arch, "rv32ia_zacas1p0"
-# CHECK: attribute      5, "rv32i2p1_a2p1_zacas1p0"
+# CHECK: attribute      5, "rv32i2p1_a2p1_zaamo1p0_zacas1p0"
 
 .attribute arch, "rv32izalasr0p1"
 # CHECK: attribute      5, "rv32i2p1_zalasr0p1"

llvm/unittests/TargetParser/RISCVISAInfoTest.cpp

@@ -660,16 +660,6 @@ TEST(ParseArchString, MissingDepency) {
     EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
               "");
   }
-
-  for (StringRef Input : {"rv32i_zacas1p0"}) {
-    EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
-              "'zacas' requires 'a' or 'zaamo' extension to also be specified");
-  }
-
-  for (StringRef Input : {"rv32i_zabha"}) {
-    EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
-              "'zabha' requires 'a' or 'zaamo' extension to also be specified");
-  }
 }
 
 TEST(ParseArchString, RejectsUnrecognizedProfileNames) {