Rephrase documentation of memoryguard

docs/yul.rst

@@ -956,16 +956,22 @@ memoryguard
 ^^^^^^^^^^^
 
 This function is available in the EVM dialect with objects. The caller of
-``let ptr := memoryguard(size)`` promises that they only use memory in either
+``let ptr := memoryguard(size)`` (where ``size`` has to be a literal number)
-the range ``[0, size)`` or the unbounded range above ``ptr``. The Yul optimizer
+promises that they only use memory in either the range ``[0, size)`` or the
-promises to only use the memory range ``[size, ptr)`` for its purposes.
+unbounded range above ``ptr``.
-If the optimizer does not need to reserve any memory, it holds that ``ptr := size``.
+
+Since the presence of a ``memoryguard`` call indicates that all memory access
+adheres to this restriction, it allows the optimizer to perform additional
+optimization steps, for example the stack limit evader, which attempts to move
+stack variables that would otherwise be unreachable to memory.
+
+The Yul optimizer promises to only use the memory range ``[size, ptr)`` for its purposes.
+If the optimizer does not need to reserve any memory, it holds that ``ptr == size``.
 
 ``memoryguard`` can be called multiple times, but needs to have the same literal as argument
 within one Yul subobject. If at least one ``memoryguard`` call is found in a subobject,
-the Yul optimiser will try to perform experimental steps like the stack limit evader,
+the additional optimiser steps will be run on it.
-which attempts to move stack variables that would otherwise be unreachable
+
-to memory.
 
 .. _yul-object: