Update: [RISCV][MC] Add support for experimental zfa extension(FLI instruction not included)

Author: joshua-arch1

llvm/docs/RISCVUsage.rst

@@ -163,6 +163,9 @@ The primary goal of experimental support is to assist in the process of ratifica
 ``experimental-zvfh``
   LLVM implements `this draft text <https://github.com/riscv/riscv-v-spec/pull/780>`_.
 
+``experimental-zfa``
+  LLVM implements a subset of `0.1 draft specification <https://github.com/riscv/riscv-isa-manual/releases/download/draft-20221119-5234c63/riscv-spec.pdf>`_ (see Chapter 25). Load-immediate instructions (fli.s/fli.d/fli.h) haven't been implemented yet.
+  
 To use an experimental extension from `clang`, you must add `-menable-experimental-extensions` to the command line, and specify the exact version of the experimental extension you are using.  To use an experimental extension with LLVM's internal developer tools (e.g. `llc`, `llvm-objdump`, `llvm-mc`), you must prefix the extension name with `experimental-`.  Note that you don't need to specify the version with internal tools, and shouldn't include the `experimental-` prefix with `clang`.
 
 Vendor Extensions

llvm/lib/Target/RISCV/AsmParser/RISCVAsmParser.cpp

@@ -483,6 +483,7 @@ struct RISCVOperand final : public MCParsedAsmOperand {
 
   /// Return true if the operand is a valid floating point rounding mode.
   bool isFRMArg() const { return Kind == KindTy::FRM; }
+  bool isRTZArg() const { return isFRMArg() && FRM.FRM == RISCVFPRndMode::RTZ; }
 
   bool isImmXLenLI() const {
     int64_t Imm;
@@ -1253,6 +1254,10 @@ bool RISCVAsmParser::MatchAndEmitInstruction(SMLoc IDLoc, unsigned &Opcode,
     SMLoc ErrorLoc = ((RISCVOperand &)*Operands[ErrorInfo]).getStartLoc();
     return Error(ErrorLoc, "operand must be a symbol with %tprel_add modifier");
   }
+  case Match_InvalidRTZArg: {
+    SMLoc ErrorLoc = ((RISCVOperand &)*Operands[ErrorInfo]).getStartLoc();
+    return Error(ErrorLoc, "operand must be 'rtz' floating-point rounding mode");
+  }
   case Match_InvalidVTypeI: {
     SMLoc ErrorLoc = ((RISCVOperand &)*Operands[ErrorInfo]).getStartLoc();
     return Error(

llvm/lib/Target/RISCV/RISCVFeatures.td

@@ -131,6 +131,14 @@ def HasStdExtZhinxOrZhinxmin
                                    "'Zhinx' (Half Float in Integer) or "
                                    "'Zhinxmin' (Half Float in Integer Minimal)">;
 
+def FeatureStdExtZfa
+    : SubtargetFeature<"experimental-zfa", "HasStdExtZfa", "true",
+                       "'Zfa' (Additional Floating-Point)",
+                       [FeatureStdExtF]>;
+def HasStdExtZfa : Predicate<"Subtarget->hasStdExtZfa()">,
+                             AssemblerPredicate<(all_of FeatureStdExtZfa),
+                             "'Zfa' (Additional Floating-Point)">;
+                             
 def FeatureStdExtC
     : SubtargetFeature<"c", "HasStdExtC", "true",
                        "'C' (Compressed Instructions)">;

llvm/lib/Target/RISCV/RISCVInstrInfo.td

@@ -1883,6 +1883,7 @@ include "RISCVInstrInfoZb.td"
 include "RISCVInstrInfoZc.td"
 include "RISCVInstrInfoZk.td"
 include "RISCVInstrInfoV.td"
+include "RISCVInstrInfoZfa.td"
 include "RISCVInstrInfoZfh.td"
 include "RISCVInstrInfoZicbo.td"