[AsmMatcher] Extend PredicateMethod with optional DiagnosticPredicate

An optional, light-weight and backward-compatible mechanism to allow
specifying that a diagnostic _only_ applies to a partial mismatch (NearMiss),
rather than a full mismatch.

Patch [1/2] in a series to improve assembler diagnostics for SVE.
-  Patch [1/2]: https://reviews.llvm.org/D45879
-  Patch [2/2]: https://reviews.llvm.org/D45880

Reviewers: olista01, stoklund, craig.topper, mcrosier, rengolin, echristo, fhahn, SjoerdMeijer, evandro, javed.absar

Reviewed By: olista01

Differential Revision: https://reviews.llvm.org/D45879

llvm-svn: 330930

1 files changed, 10 insertions, 4 deletions

diff --git a/llvm/utils/TableGen/AsmMatcherEmitter.cpp b/llvm/utils/TableGen/AsmMatcherEmitter.cpp
index 3fbd3c69920..5b805e340ed 100644
--- a/llvm/utils/TableGen/AsmMatcherEmitter.cpp
+++ b/llvm/utils/TableGen/AsmMatcherEmitter.cpp
@@ -2451,14 +2451,20 @@ static void emitValidateOperandClass(AsmMatcherInfo &Info,
       continue;
 
     OS << "  // '" << CI.ClassName << "' class\n";
-    OS << "  case " << CI.Name << ":\n";
-    OS << "    if (Operand." << CI.PredicateMethod << "())\n";
+    OS << "  case " << CI.Name << ": {\n";
+    OS << "    DiagnosticPredicate DP(Operand." << CI.PredicateMethod
+       << "());\n";
+    OS << "    if (DP.isMatch())\n";
     OS << "      return MCTargetAsmParser::Match_Success;\n";
-    if (!CI.DiagnosticType.empty())
-      OS << "    return " << Info.Target.getName() << "AsmParser::Match_"
+    if (!CI.DiagnosticType.empty()) {
+      OS << "    if (DP.isNearMatch())\n";
+      OS << "      return " << Info.Target.getName() << "AsmParser::Match_"
          << CI.DiagnosticType << ";\n";
+      OS << "    break;\n";
+    }
     else
       OS << "    break;\n";
+    OS << "    }\n";
   }
   OS << "  } // end switch (Kind)\n\n";