Update the maximum integer bitwidth in MLIR.

[darthscsi]

Summary

Large integers are generated in Circt commonly which exceed 4kbits. This aligns the maximum bitwidth in MLIR and LLVM.

[rriddle]

mlir/include/mlir/IR/BuiltinTypes.h

142

How did you come up with this number?

[lattner]

LLVM uses "MAX_INT_BITS = (1<<24)-1". Unless there is a reason to be different, it would probably be good to align with that.

[darthscsi]

Align with llvm

[jpienaar]

Nit: on review description, this is updating the maximum _bitwidth_ of integer types, not maximum integer size (i4096 can represent integers up to 1.04e+1233)

[mehdi_amini]

mlir/include/mlir/IR/BuiltinTypes.h

142

Can you just also document that this is aligned with LLVM?

[lattner]

Nice, thanks darthscsi

[bondhugula]

Can you please add a proper commit summary with the rationale (basically whatever is in the discussion now)? Also, as @jpienaar points out, the commit title isn't really accurate.

[darthscsi]

Update the maximum integer bitwidth in MLIR.

Large integers are generated in Circt commonly which exceed 4k. This aligns MLIR's width to llvm.

[rriddle]

mlir/include/mlir/IR/BuiltinTypes.h

142

mlir/include/mlir/IR/BuiltinTypes.h

public:
   bool isUnsigned() const { return getSignedness() == Unsigned; }
 
   /// Get or create a new IntegerType with the same signedness as `this` and a
   /// bitwidth scaled by `scale`.
   /// Return null if the scaled element type cannot be represented.
   IntegerType scaleElementBitwidth(unsigned scale);
 
   /// Integer representation maximal bitwidth.
-  static constexpr unsigned kMaxWidth = 4096;
+  static constexpr unsigned kMaxWidth = (1 << 24) - 1; // Aligned with LLVM
 };
 
 //===----------------------------------------------------------------------===//
 // FloatType
 //===----------------------------------------------------------------------===//
 
 class FloatType : public Type {
 public:

mlir/test/IR/invalid-ops.mlir

^bb0:
   %0 = alloc() : memref<1024x64xf32, affine_map<(d0) -> (d0)>, 1> // expected-error {{memref affine map dimension mismatch}}
   return
 }
 
 // -----
 
 func @intlimit2() {
 ^bb:
-  %0 = "std.constant"() {value = 0} : () -> i4096
-  %1 = "std.constant"() {value = 1} : () -> i4097 // expected-error {{integer bitwidth is limited to 4096 bits}}
+  %0 = "std.constant"() {value = 0} : () -> i16777215
+  %1 = "std.constant"() {value = 1} : () -> i16777216 // expected-error {{integer bitwidth is limited to 16777215 bits}}
   return
 }
 
 // -----
 
 func @calls(%arg0: i32) {
   %x = call @calls() : () -> i32  // expected-error {{incorrect number of operands for callee}}
   return