RISC-V: restrict inclusion of Zcf by Zce

Currently, the Zce extension includes Zcf unconditionally; however, according
to the Zc* spec version 1.0.4 [1]:

* Specifying Zce on RV32 without F includes Zca, Zcb, Zcmp, Zcmt
* Specifying Zce on RV32 with F includes Zca, Zcb, Zcmp, Zcmt and Zcf
* Specifying Zce on RV64 always includes Zca, Zcb, Zcmp, Zcmt
    - Zcf doesn’t exist for RV64

This patch checks whether (a) F is enabled and (b) the target is 32-bit; to
that end, the check_func() helper receives the current list of used extensions
(riscv_parse_subset_t *) as a third parameter so that the information about
currently enabled extensions and the target can be retrieved.

[1] https://github.com/riscvarchive/riscv-code-size-reduction/releases/download/v1.0.4-3/Zc-1.0.4-3.pdf

Signed-off-by: Artemiy Volkov <[email protected]>

Conflicts:
	bfd/elfxx-riscv.c

Author: artemiy-volkov

bfd/elfxx-riscv.c

@@ -1148,28 +1148,45 @@ riscv_elf_ignore_reloc (bfd *abfd ATTRIBUTE_UNUSED,
 /* Always add implicit extensions for the SUBSET.  */
 
 static bool
-check_implicit_always (riscv_subset_t *subset ATTRIBUTE_UNUSED)
+check_implicit_always (const char *implicit ATTRIBUTE_UNUSED,
+		       riscv_parse_subset_t *rps ATTRIBUTE_UNUSED,
+		       riscv_subset_t *subset ATTRIBUTE_UNUSED)
 {
   return true;
 }
 
 /* Add implicit extensions only when the version of SUBSET less than 2.1.  */
 
 static bool
-check_implicit_for_i (riscv_subset_t *subset)
+check_implicit_for_i (const char *implicit ATTRIBUTE_UNUSED,
+		      riscv_parse_subset_t *rps ATTRIBUTE_UNUSED,
+		      riscv_subset_t *subset)
 {
   return (subset->major_version < 2
 	  || (subset->major_version == 2
 	      && subset->minor_version < 1));
 }
 
+/* Zce includes Zcf only in the presence of F, and only if the target is
+   32-bit (see Zc* v1.0.4 section 1.4).  */
+
+static bool
+check_implicit_for_zce_zcf (const char *implicit ATTRIBUTE_UNUSED,
+			    riscv_parse_subset_t *rps,
+			    riscv_subset_t *subset ATTRIBUTE_UNUSED)
+{
+  riscv_subset_t *current;
+  return riscv_lookup_subset (rps->subset_list, "f", &current)
+	  && *rps->xlen == 32;
+}
+
 /* Record all implicit information for the subsets.  */
 struct riscv_implicit_subset
 {
   const char *ext;
   const char *implicit_exts;
   /* A function to determine if we need to add the implicit subsets.  */
-  bool (*check_func) (riscv_subset_t *);
+  bool (*check_func) (const char *, riscv_parse_subset_t *, riscv_subset_t *);
 };
 /* Please added in order since this table is only run once time.  */
 static struct riscv_implicit_subset riscv_implicit_subsets[] =
@@ -1211,7 +1228,8 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
 
   {"zcb", "+zca", check_implicit_always},
   {"zcd", "+d,+zca", check_implicit_always},
-  {"zce", "+zca,+zcb,+zcf,+zcmp,+zcmt", check_implicit_always},
+  {"zce", "+zca,+zcb,+zcmp,+zcmt", check_implicit_always},
+  {"zce", "+zcf", check_implicit_for_zce_zcf},
   {"zcf", "+f,+zca", check_implicit_always},
   {"zcmp", "+zca", check_implicit_always},
   {"zcmt", "+zca", check_implicit_always},
@@ -1271,6 +1289,8 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
   {"svade", "+zicsr", check_implicit_always},
   {"svadu", "+zicsr", check_implicit_always},
   {"svbare", "+zicsr", check_implicit_always},
+
+  {"xsfvcp", "zve32x",  check_implicit_always},
   {NULL, NULL, NULL}
 };
 
@@ -2042,7 +2062,7 @@ riscv_parse_add_implicit_subsets (riscv_parse_subset_t *rps)
     {
       riscv_subset_t *subset = NULL;
       if (riscv_lookup_subset (rps->subset_list, t->ext, &subset)
-	&& t->check_func (subset))
+	&& t->check_func (t->implicit_exts, rps, subset))
       riscv_update_subset1 (rps, subset, t->implicit_exts);
     }
 }