[clang] [llvm] [RISCV] Add MC layer support for XSfmm*. (PR #133031)

[Philip Reames via llvm-commits]

================
@@ -2302,6 +2316,81 @@ bool RISCVAsmParser::generateVTypeError(SMLoc ErrorLoc) {
       "e[8|16|32|64],m[1|2|4|8|f2|f4|f8],[ta|tu],[ma|mu]");
 }
 
+bool RISCVAsmParser::parseXSfmmVTypeToken(const AsmToken &Tok, WWEEState &State,
+                                          unsigned &WW, unsigned &EE,
+                                          bool &AltFmt) {
+  if (getLexer().isNot(AsmToken::Identifier))
+    return true;
+
+  StringRef Identifier = getTok().getIdentifier();
+
+  switch (State) {
+  case WWEEState_SEW:
+    if (!Identifier.consume_front("e"))
+      break;
+    if (Identifier.getAsInteger(10, EE)) {
+      if (Identifier != "16alt")
+        break;
+
+      AltFmt = true;
+      EE = 16;
+    }
+    if (!RISCVVType::isValidSEW(EE))
+      break;
+    State = WWEEState_Widen;
+    return false;
+  case WWEEState_Widen:
+    if (!Identifier.consume_front("w"))
+      break;
+    if (Identifier.getAsInteger(10, WW))
+      break;
+    if (WW != 1 && WW != 2 && WW != 4)
+      break;
+    State = WWEEState_Done;
+    return false;
+  case WWEEState_Done:
+    // Extra token?
+    break;
+  }
+
+  return true;
+}
+
+ParseStatus RISCVAsmParser::parseXSfmmVType(OperandVector &Operands) {
+  SMLoc S = getLoc();
+
+  unsigned Widen = 0;
+  unsigned SEW = 0;
+  bool AltFmt = false;
+
+  WWEEState State = WWEEState_SEW;
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preames wrote:

It's not really clear to me that the state mechanism is worthwhile over just inlining the two calls and specializing the switch.  The state machine is exceedingly simple, and the extra helper may actually just confuse things.

https://github.com/llvm/llvm-project/pull/133031