[gcc r12-3032] Document enable_ranger and disable_ranger.

[gcc r12-3032] Document enable_ranger and disable_ranger.

[Martin Sebor]

https://gcc.gnu.org/g:77bf9f83b8e388de8bedb259991f588a7b8a7f57

commit r12-3032-g77bf9f83b8e388de8bedb259991f588a7b8a7f57
Author: Martin Sebor <msebor@redhat.com>
Date:   Thu Aug 19 12:49:40 2021 -0600

    Document enable_ranger and disable_ranger.
    
    gcc:
            * gimple-range.cc: Add comments.
            * gimple-range.h: Same.

Diff:
---
 gcc/gimple-range.cc | 7 +++++++
 gcc/gimple-range.h  | 3 +++
 2 files changed, 10 insertions(+)

diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index 60b7d3a59cd..ef3afeacc90 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -381,6 +381,10 @@ gimple_ranger::dump (FILE *f)
   m_cache.dump (f);
 }
 
+/* Create a new ranger instance and associate it with function FUN.
+   Each call must be paired with a call to disable_ranger to release
+   resources.  */
+
 gimple_ranger *
 enable_ranger (struct function *fun)
 {
@@ -392,6 +396,9 @@ enable_ranger (struct function *fun)
   return r;
 }
 
+/* Destroy and release the ranger instance associated with function FUN
+   and replace it the global ranger.  */
+
 void
 disable_ranger (struct function *fun)
 {
diff --git a/gcc/gimple-range.h b/gcc/gimple-range.h
index 41845b14fd6..eaebb9c5833 100644
--- a/gcc/gimple-range.h
+++ b/gcc/gimple-range.h
@@ -62,6 +62,9 @@ protected:
   range_tracer tracer;
 };
 
+/* Create a new ranger instance and associate it with a function.
+   Each call must be paired with a call to disable_ranger to release
+   resources.  */
 extern gimple_ranger *enable_ranger (struct function *);
 extern void disable_ranger (struct function *);