Avoid hardcoded 4096 constant

This commit creates a static constexpr limit for the IntegerType
bitwidth and uses it. The check had to be moved because Token is
not aware of IR/Type and it was a sign the abstraction leaked:
bitwidth limit is not a property of the Token but of the IntegerType.

Added a positive and a negative test at the limit.

PiperOrigin-RevId: 210388192

2 files changed, 5 insertions, 3 deletions

diff --git a/mlir/lib/Parser/Parser.cpp b/mlir/lib/Parser/Parser.cpp
index 285312f658e..756f25d8bbd 100644
--- a/mlir/lib/Parser/Parser.cpp
+++ b/mlir/lib/Parser/Parser.cpp
@@ -316,6 +316,10 @@ Type *Parser::parseType() {
     auto width = getToken().getIntTypeBitwidth();
     if (!width.hasValue())
       return (emitError("invalid integer width"), nullptr);
+    if (width > IntegerType::kMaxWidth)
+      return (emitError("integer bitwidth is limited to " +
+                        Twine(IntegerType::kMaxWidth) + " bits"),
+              nullptr);
     consumeToken(Token::inttype);
     return builder.getIntegerType(width.getValue());
   }
diff --git a/mlir/lib/Parser/Token.cpp b/mlir/lib/Parser/Token.cpp
index 4c3f9e4258e..4e01f5a6a53 100644
--- a/mlir/lib/Parser/Token.cpp
+++ b/mlir/lib/Parser/Token.cpp
@@ -72,9 +72,7 @@ Optional<double> Token::getFloatingPointValue() const {
 Optional<unsigned> Token::getIntTypeBitwidth() const {
   unsigned result = 0;
   if (spelling[1] == '0' ||
-      spelling.drop_front().getAsInteger(10, result) ||
-      // Arbitrary but large limit on bitwidth.
-      result > 4096 || result == 0)
+      spelling.drop_front().getAsInteger(10, result) || result == 0)
     return None;
   return result;
 }