[PATCH] D99892: [flang] Improve constant folding for type parameter inquiries

[Pete Steinfeld via Phabricator via llvm-commits]

PeteSteinfeld added inline comments.


================
Comment at: flang/lib/Evaluate/fold-integer.cpp:664
+  if (base) {
+    // Handling "designator%typeParam".  Get the value of the type parameter
+    // from the instantiation of the base
----------------
klausler wrote:
> LEN type parameter inquiries are not safe to fold in all cases; the actual LEN parameter expression may not be constant.  Consider
> 
>   subroutine foo(n)
>     type :: t(len)
>     integer, len :: len
>     end type t
>     type(t(n)) :: x
>     n = n + 1
>     print *, x%len
>   end
> 
> The value of x%len at its point of use needs to return the original value of the dummy argument, not its later updated value.
> 
> In general, folding type parameter inquiries can be done only for KIND= parameters and for LEN= parameters whose expressions are constant expressions.
D'oh!  I had intended for this new code to  be specific to constant expressions, and I just realized that I didn't test for that.  Stay tuned for an update.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D99892/new/

https://reviews.llvm.org/D99892