[CHERIoT] Make operand predicates more lenient in places where it is needed to enable ct-prefixed instruction mnemonics.

Author: resistor

llvm/lib/Target/RISCV/RISCVInstrInfo.td

@@ -263,6 +263,10 @@ def simm12 : RISCVSImmLeafOp<12> {
     int64_t Imm;
     if (MCOp.evaluateAsConstantImm(Imm))
       return isInt<12>(Imm);
+    // Needed to make CHERIOT mnemonic aliases work.
+    if (STI.hasFeature(RISCV::FeatureVendorXCheriot) &&
+        MCOp.isExpr())
+      return true;
     return MCOp.isBareSymbolRef();
   }];
 }
@@ -292,6 +296,10 @@ class UImm20OperandMaybeSym : RISCVUImmOp<20> {
     int64_t Imm;
     if (MCOp.evaluateAsConstantImm(Imm))
       return isUInt<20>(Imm);
+    // Needed to make CHERIOT mnemonic aliases work.
+    if (STI.hasFeature(RISCV::FeatureVendorXCheriot) &&
+        MCOp.isExpr())
+      return true;
     return MCOp.isBareSymbolRef();
   }];
 }

llvm/lib/Target/RISCV/RISCVInstrInfoXCheri.td

@@ -2056,9 +2056,8 @@ def PseudoCTAIL : Pseudo<(outs), (ins cap_call_symbol:$dst), []> {
   let AsmString = "ctail\t$dst";
 }
 
-let Predicates = [HasCheriot] in def : InstAlias<
-                                           "ct.ctail $dst",
-                                           (PseudoCTAIL cap_call_symbol:$dst)>;
+let Predicates = [HasCheriot] in
+def : InstAlias<"ct.ctail $dst", (PseudoCTAIL cap_call_symbol:$dst)>;
 
 let Predicates = [HasCheri, IsCapMode, IsPureCapABI],
     isCall = 1, isTerminator = 1, isReturn = 1, isBarrier = 1, Uses = [C2] in

llvm/test/MC/RISCV/cheri/cheriot-only.s

@@ -0,0 +1,9 @@
+// NOTE: Assertions have been autogenerated by utils/update_mc_test_checks.py UTC_ARGS: --version 5
+// RUN: llvm-mc %s -triple=riscv32cheriot -mcpu=cheriot -mattr=+xcheri,+xcheriot | FileCheck %s -check-prefixes=CHERIOT
+
+foo:
+// CHERIOT: foo:
+    auipcc ct3, %cheriot_compartment_hi(foo)
+// CHERIOT: ct.auipcc	ct3, %cheriot_compartment_hi(foo)
+    clc  ct2, %cheriot_compartment_lo_i(foo)(ct2)
+// CHERIOT: ct.clc	ct2, %cheriot_compartment_lo_i(foo)(ct2)

llvm/test/MC/RISCV/cheri/cheriot.s

@@ -119,4 +119,4 @@ ctestsubset x7, ca5, ca3
 // CHERI: ctestsubset	t2, ca5, ca3            # encoding: [0xdb,0x83,0xd7,0x40]
 cunseal ca5, ca3, ca1
 // CHERIOT: ct.cunseal	ca5, ca3, ca1           # encoding: [0xdb,0x87,0xb6,0x18]
-// CHERI: cunseal	ca5, ca3, ca1                   # encoding: [0xdb,0x87,0xb6,0x18]
+// CHERI: cunseal	ca5, ca3, ca1                   # encoding: [0xdb,0x87,0xb6,0x18]