https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66790
--- Comment #22 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> A native English speaker would say that this could be written better. I
> would suggest the term "on at least one path" and this is what a MAY problem
> is generally defined as.
Thanks. Here's a proposed amended wording:
Index: df-problems.c
===================================================================
--- df-problems.c (revision 227819)
+++ df-problems.c (working copy)
@@ -1309,22 +1309,23 @@ df_lr_verify_transfer_functions (void)
/*----------------------------------------------------------------------------
- LIVE AND MUST-INITIALIZED REGISTERS.
+ LIVE AND MAY-INITIALIZED REGISTERS.
This problem first computes the IN and OUT bitvectors for the
- must-initialized registers problems, which is a forward problem.
- It gives the set of registers for which we MUST have an available
- definition on any path from the entry block to the entry/exit of
- a basic block. Sets generate a definition, while clobbers kill
+ may-initialized registers problems, which is a forward problem.
+ It gives the set of registers for which we MAY have an available
+ definition, i.e. for which there is an available definition on
+ at least one path from the entry block to the entry/exit of a
+ basic block. Sets generate a definition, while clobbers kill
a definition.
In and out bitvectors are built for each basic block and are indexed by
regnum (see df.h for details). In and out bitvectors in struct
- df_live_bb_info actually refers to the must-initialized problem;
+ df_live_bb_info actually refers to the may-initialized problem;
Then, the in and out sets for the LIVE problem itself are computed.
These are the logical AND of the IN and OUT sets from the LR problem
- and the must-initialized problem.
+ and the may-initialized problem.
----------------------------------------------------------------------------*/
/* Private data used to verify the solution for this problem. */
@@ -1531,7 +1532,7 @@ df_live_confluence_n (edge e)
}
-/* Transfer function for the forwards must-initialized problem. */
+/* Transfer function for the forwards may-initialized problem. */
static bool
df_live_transfer_function (int bb_index)
@@ -1555,7 +1556,7 @@ df_live_transfer_function (int bb_index)
}
-/* And the LR info with the must-initialized registers, to produce the LIVE
info. */
+/* And the LR info with the may-initialized registers, to produce the LIVE
info. */
static void
df_live_finalize (bitmap all_blocks)
