Modified assume_alignment description

Changed assertion to assumption and improved description of poison

Author: Shay Kleiman

mlir/include/mlir/Dialect/MemRef/IR/MemRefOps.td

@@ -144,25 +144,21 @@ class AllocLikeOp<string mnemonic,
 
 def AssumeAlignmentOp : MemRef_Op<"assume_alignment", [
       DeclareOpInterfaceMethods<OpAsmOpInterface, ["getAsmResultNames"]>,
-      Pure, 
+      Pure,
       ViewLikeOpInterface,
       SameOperandsAndResultType
     ]> {
   let summary =
-      "assertion that gives alignment information to the input memref";
+      "assumption that gives alignment information to the input memref";
   let description = [{
-      The `assume_alignment` operation takes a memref and an integer of alignment
+      The `assume_alignment` operation takes a memref and an integer alignment
       value. It returns a new SSA value of the same memref type, but associated
-      with the assertion that the underlying buffer is aligned to the given
+      with the assumption that the underlying buffer is aligned to the given
       alignment. 
 
-      If the buffer isn't aligned to the given alignment, this operation
-      itself does not cause undefined behavior. However, subsequent operations
-      that consume the resulting memref and rely on this asserted alignment for
-      correctness will produce a poison value if the assertion is false.
-
+      If the buffer isn't aligned to the given alignment, its result is poison.
       This operation doesn't affect the semantics of a program where the
-      alignment assertion holds true. It is intended for optimization purposes,
+      alignment assumption holds true. It is intended for optimization purposes,
       allowing the compiler to generate more efficient code based on the
       alignment assumption. The optimization is best-effort.
   }];