[PATCH] D17568: [TableGen] AsmMatcher: Skip optional operands in the midle of instruction if it is not present

[Sam Kolton via llvm-commits]

SamWot created this revision.
SamWot added reviewers: tstellarAMD, ab, olista01.
SamWot added subscribers: arsenm, nhaustov, llvm-commits.

Previosy, if actual instruction have one of optional operands then other optional operands listed before this also should be presented.
For example instruction v_fract_f32 v0, v1, mul:2 have one optional operand - OMod and do not have optional operand clamp. Previously this was not allowed because clamp is listed before omod in AsmString:
```
string AsmString = "v_fract_f32$vdst, $src0_modifiers$clamp$omod";
```
Making this work required some hacks (both OMod and Clamp match classes have same PredicateMethod).

Now, if MatchInstructionImpl meets formal optional operand that is not presented in actual instruction it skips this formal operand and tries to match current actual operand with next formal. 

http://reviews.llvm.org/D17568

Files:
  utils/TableGen/AsmMatcherEmitter.cpp

Index: utils/TableGen/AsmMatcherEmitter.cpp
===================================================================
--- utils/TableGen/AsmMatcherEmitter.cpp
+++ utils/TableGen/AsmMatcherEmitter.cpp
@@ -3108,37 +3108,42 @@
 
   // Emit check that the subclasses match.
   OS << "    bool OperandsValid = true;\n";
-  OS << "    for (unsigned i = " << (HasMnemonicFirst ? "0" : "SIndex")
-     << "; i != " << MaxNumOperands << "; ++i) {\n";
-  OS << "      auto Formal = static_cast<MatchClassKind>(it->Classes[i]);\n";
-  OS << "      if (i" << (HasMnemonicFirst ? "+1" : "")
-     << " >= Operands.size()) {\n";
+  OS << "    for (unsigned FormalIdx = " << (HasMnemonicFirst ? "0" : "SIndex")
+     << ", ActualIdx = " << (HasMnemonicFirst ? "1" : "SIndex")
+     << "; FormalIdx != " << MaxNumOperands << "; ++FormalIdx) {\n";
+  OS << "      auto Formal = "
+     << "static_cast<MatchClassKind>(it->Classes[FormalIdx]);\n";
+  OS << "      if (ActualIdx >= Operands.size()) {\n";
   OS << "        OperandsValid = (Formal == " <<"InvalidMatchClass) || "
                                  "isSubclass(Formal, OptionalMatchClass);\n";
-  OS << "        if (!OperandsValid) ErrorInfo = i"
-     << (HasMnemonicFirst ? "+1" : "") << ";\n";
+  OS << "        if (!OperandsValid) ErrorInfo = ActualIdx;\n";
   OS << "        break;\n";
   OS << "      }\n";
-  OS << "      MCParsedAsmOperand &Actual = *Operands[i"
-     << (HasMnemonicFirst ? "+1" : "") << "];\n";
+  OS << "      MCParsedAsmOperand &Actual = *Operands[ActualIdx];\n";
   OS << "      unsigned Diag = validateOperandClass(Actual, Formal);\n";
-  OS << "      if (Diag == Match_Success)\n";
+  OS << "      if (Diag == Match_Success) {\n";
+  OS << "        ++ActualIdx;\n";
   OS << "        continue;\n";
+  OS << "      }\n";
   OS << "      // If the generic handler indicates an invalid operand\n";
   OS << "      // failure, check for a special case.\n";
   OS << "      if (Diag == Match_InvalidOperand) {\n";
   OS << "        Diag = validateTargetOperandClass(Actual, Formal);\n";
-  OS << "        if (Diag == Match_Success)\n";
+  OS << "        if (Diag == Match_Success) {\n";
+  OS << "          ++ActualIdx;\n";
   OS << "          continue;\n";
+  OS << "        }\n";
   OS << "      }\n";
+  OS << "      if (Diag == Match_InvalidOperand "
+     << "&& isSubclass(Formal, OptionalMatchClass))\n";
+  OS << "        continue;\n";
   OS << "      // If this operand is broken for all of the instances of this\n";
   OS << "      // mnemonic, keep track of it so we can report loc info.\n";
   OS << "      // If we already had a match that only failed due to a\n";
   OS << "      // target predicate, that diagnostic is preferred.\n";
   OS << "      if (!HadMatchOtherThanPredicate &&\n";
-  OS << "          (it == MnemonicRange.first || ErrorInfo <= i"
-     << (HasMnemonicFirst ? "+1" : "") << ")) {\n";
-  OS << "        ErrorInfo = i" << (HasMnemonicFirst ? "+1" : "") << ";\n";
+  OS << "          (it == MnemonicRange.first || ErrorInfo <= ActualIdx)) {\n";
+  OS << "        ErrorInfo = ActualIdx;\n";
   OS << "        // InvalidOperand is the default. Prefer specificity.\n";
   OS << "        if (Diag != Match_InvalidOperand)\n";
   OS << "          RetCode = Diag;\n";


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