Brendon Costa wrote: > I want to use GCC to categorise "functional purity" in C++. My > definition will differ from classic functional purity. In particular: > > A function is considered pure if it makes no changes to existing > memory or program state. There may be a few exceptions to this rule > such as for new/malloc in that they change program state (allocating > new memory) but will be manually marked as pure. However free/delete > should be marked as impure (modifying function parameter, but not > global state). This means that a function which is pure can create new > objects/memory and make changes to those new objects, but the existing > memory must remain unchanged. > > When categorising a functions purity i also would like to identify the > cause of the impurity. In particular for a function that is impure i > want to categorise the impurity cause as: > * modifies global state > * modifies a function parameter > * modifies the object state (this is an extension of the function > parameter on the "this" parameter) > > The reason for posting this is to ask. Is there code in GCC that > already does something "similar" in say one of the optimisation passes > so i can get a look at how to get started on this?
This sounds very similar to gimple_has_side_effects (). Also have a look at ECF_CONST and ECF_PURE. Andrew.
