Use Coq strings instead of idents to name external and builtin functions.

The AST.ident type represents source-level identifiers as unique positive numbers.  However, the mapping identifiers <-> AST.ident differs between runs of CompCert on different source files.  This is problematic when we need to produce or recognize external functions and builtin functions with fixed names, for example:
* in $ARCH/Machregs.v to define the register conventions for builtin functions;
* in the VST program logic from Princeton to treat thread primitives specially.

So far, we used AST.ident_of_string to recover the ident associated with a string.  However, this function is defined in OCaml and doesn't execute within Coq.  This is a problem both for VST and for future executability of CompCert within Coq.

This commit replaces "ident" by "string" in the arguments of EF_external, EF_builtin, EF_inline_asm, EF_annot, and EF_annot_val.  This provides stable names for externals and builtins, as needed.  For inline asm and annotations, it's a matter of taste, but using strings feels more natural.  EF_debug keeps using idents, since some kinds of EF_debug annotations talk about program variables.

1 files changed, 4 insertions, 4 deletions

diff --git a/cfrontend/Cexec.v b/cfrontend/Cexec.v
index 16d5823b..938454c5 100644
--- a/cfrontend/Cexec.v
+++ b/cfrontend/Cexec.v
@@ -391,7 +391,7 @@ Qed.
 (** External calls *)
 
 Variable do_external_function:
-  ident -> signature -> Senv.t -> world -> list val -> mem -> option (world * trace * val * mem).
+  string -> signature -> Senv.t -> world -> list val -> mem -> option (world * trace * val * mem).
 
 Hypothesis do_external_function_sound:
   forall id sg ge vargs m t vres m' w w',
@@ -405,7 +405,7 @@ Hypothesis do_external_function_complete:
   do_external_function id sg ge w vargs m = Some(w', t, vres, m').
 
 Variable do_inline_assembly:
-  ident -> signature -> Senv.t -> world -> list val -> mem -> option (world * trace * val * mem).
+  string -> signature -> Senv.t -> world -> list val -> mem -> option (world * trace * val * mem).
 
 Hypothesis do_inline_assembly_sound:
   forall txt sg ge vargs m t vres m' w w',
@@ -513,12 +513,12 @@ Definition do_ef_memcpy (sz al: Z)
   | _ => None
   end.
 
-Definition do_ef_annot (text: ident) (targs: list typ)
+Definition do_ef_annot (text: string) (targs: list typ)
        (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
   do args <- list_eventval_of_val vargs targs;
   Some(w, Event_annot text args :: E0, Vundef, m).
 
-Definition do_ef_annot_val (text: ident) (targ: typ)
+Definition do_ef_annot_val (text: string) (targ: typ)
        (w: world) (vargs: list val) (m: mem) : option (world * trace * val * mem) :=
   match vargs with
   | varg :: nil =>