[RISCV] Report error if Zilsd is used on RV64. (llvm#136577)

Fixes llvm#136564.

Author: topperc

llvm/lib/TargetParser/RISCVISAInfo.cpp

@@ -789,6 +789,9 @@ Error RISCVISAInfo::checkDependency() {
       return getIncompatibleError("zclsd", "zcf");
   }
 
+  if (XLen != 32 && Exts.count("zilsd") != 0)
+    return getError("'zilsd' is only supported for 'rv32'");
+
   for (auto Ext : XqciExts)
     if (Exts.count(Ext.str()) && (XLen != 32))
       return getError("'" + Twine(Ext) + "'" + " is only supported for 'rv32'");

llvm/unittests/TargetParser/RISCVISAInfoTest.cpp

@@ -658,6 +658,16 @@ TEST(ParseArchString, RejectsConflictingExtensions) {
               "'xwchc' and 'zcb' extensions are incompatible");
   }
 
+  for (StringRef Input : {"rv64i_zilsd"}) {
+    EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
+              "'zilsd' is only supported for 'rv32'");
+  }
+
+  for (StringRef Input : {"rv64i_zclsd"}) {
+    EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
+              "'zclsd' is only supported for 'rv32'");
+  }
+
   for (StringRef Input : {"rv32i_zcf_zclsd"}) {
     EXPECT_EQ(toString(RISCVISAInfo::parseArchString(Input, true).takeError()),
               "'zclsd' and 'zcf' extensions are incompatible");