xtensa: allow runtime ABI selection

2020-06-15  Max Filippov  <jcmvbkbc@gmail.com>
bfd/
	* elf32-xtensa.c (XSHAL_ABI, XTHAL_ABI_UNDEFINED)
	(XTHAL_ABI_WINDOWED, XTHAL_ABI_CALL0): New macros.
	(elf32xtensa_abi): New global variable.
	(xtensa_abi_choice): New function.
	(elf_xtensa_create_plt_entry): Use xtensa_abi_choice instead of
	XSHAL_ABI to select PLT code.

gas/
	* config/tc-xtensa.c (XTHAL_ABI_WINDOWED, XTHAL_ABI_CALL0): New
	macros.
	(elf32xtensa_abi): New declaration.
	(option_abi_windowed, option_abi_call0): New enum constants.
	(md_longopts): Add entries for --abi-windowed and --abi-call0.
	(md_parse_option): Add handlers for --abi-windowed and
	--abi-call0.
	(xtensa_add_config_info): Use xtensa_abi_choice instead of
	XSHAL_ABI to format ABI tag.
	* doc/as.texi (Target Xtensa options): Add --abi-windowed and
	--abi-call0 to the list of options.
	* doc/c-xtensa.texi: Add description for options --abi-windowed
	and --abi-call0.
	* testsuite/gas/xtensa/abi-call0.d: New test definition.
	* testsuite/gas/xtensa/abi-windowed.d: New test definition.
	* testsuite/gas/xtensa/abi.s: New test source.

include/
	* elf/xtensa.h (xtensa_abi_choice): New declaration.

ld/
	* emultempl/xtensaelf.em (XSHAL_ABI): Remove macro definition.
	(XTHAL_ABI_UNDEFINED, XTHAL_ABI_WINDOWED, XTHAL_ABI_CALL0): New
	macros.
	(elf32xtensa_abi): New declaration.
	(xt_config_info_unpack_and_check): Set elf32xtensa_abi if it is
	undefined.  Use xtensa_abi_choice instead of XSHAL_ABI to test
	ABI tag consistency.
	(xtensa_add_config_info): Use xtensa_abi_choice instead of
	XSHAL_ABI to format ABI tag.
	(PARSE_AND_LIST_PROLOGUE): Define OPTION_ABI_WINDOWED,
	OPTION_ABI_CALL0 and declare elf32xtensa_abi.
	(PARSE_AND_LIST_LONGOPTS): Add entries for --abi-windowed and
	--abi-call0.
	(PARSE_AND_LIST_OPTIONS): Add help text for --abi-windowed and
	--abi-call0.
	(PARSE_AND_LIST_ARGS_CASES): Add handlers for --abi-windowed and
	--abi-call0.
	* ld.texi: Add description for options --abi-windowed and
	--abi-call0.

3 files changed, 69 insertions, 5 deletions

diff --git a/ld/ChangeLog b/ld/ChangeLog
index 6700e72..73a99a0 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,25 @@
+2020-06-15  Max Filippov  <jcmvbkbc@gmail.com>
+
+	* emultempl/xtensaelf.em (XSHAL_ABI): Remove macro definition.
+	(XTHAL_ABI_UNDEFINED, XTHAL_ABI_WINDOWED, XTHAL_ABI_CALL0): New
+	macros.
+	(elf32xtensa_abi): New declaration.
+	(xt_config_info_unpack_and_check): Set elf32xtensa_abi if it is
+	undefined.  Use xtensa_abi_choice instead of XSHAL_ABI to test
+	ABI tag consistency.
+	(xtensa_add_config_info): Use xtensa_abi_choice instead of
+	XSHAL_ABI to format ABI tag.
+	(PARSE_AND_LIST_PROLOGUE): Define OPTION_ABI_WINDOWED,
+	OPTION_ABI_CALL0 and declare elf32xtensa_abi.
+	(PARSE_AND_LIST_LONGOPTS): Add entries for --abi-windowed and
+	--abi-call0.
+	(PARSE_AND_LIST_OPTIONS): Add help text for --abi-windowed and
+	--abi-call0.
+	(PARSE_AND_LIST_ARGS_CASES): Add handlers for --abi-windowed and
+	--abi-call0.
+	* ld.texi: Add description for options --abi-windowed and
+	--abi-call0.
+
 2020-06-15  Roland McGrath  <mcgrathr@google.com>
 
 	* NEWS: Mention -z start-stop-visibility=... option for ELF.
diff --git a/ld/emultempl/xtensaelf.em b/ld/emultempl/xtensaelf.em
index 932721c..53f40c2 100644
--- a/ld/emultempl/xtensaelf.em
+++ b/ld/emultempl/xtensaelf.em
@@ -30,8 +30,16 @@ fragment <<EOF
 #include "bfd.h"
 
 /* Provide default values for new configuration settings.  */
-#ifndef XSHAL_ABI
-#define XSHAL_ABI 0
+#ifndef XTHAL_ABI_UNDEFINED
+#define XTHAL_ABI_UNDEFINED -1
+#endif
+
+#ifndef XTHAL_ABI_WINDOWED
+#define XTHAL_ABI_WINDOWED 0
+#endif
+
+#ifndef XTHAL_ABI_CALL0
+#define XTHAL_ABI_CALL0 1
 #endif
 
 static void xtensa_wild_group_interleave (lang_statement_union_type *);
@@ -49,6 +57,10 @@ static bfd_boolean xtensa_use_literal_pages = FALSE;
 
 #define EXTRA_VALIDATION 0
 
+/* Xtensa ABI.
+   This option is defined in BDF library.  */
+extern int elf32xtensa_abi;
+
 
 static char *
 elf_xtensa_choose_target (int argc ATTRIBUTE_UNUSED,
@@ -306,7 +318,7 @@ xt_config_info_unpack_and_check (char *data,
 				 char **pmsg)
 {
   char *d, *key;
-  unsigned num;
+  int num;
 
   *pmismatch = FALSE;
 
@@ -341,7 +353,11 @@ xt_config_info_unpack_and_check (char *data,
 
 	  if (! strcmp (key, "ABI"))
 	    {
-	      if (num != XSHAL_ABI)
+	      if (elf32xtensa_abi == XTHAL_ABI_UNDEFINED)
+		{
+		  elf32xtensa_abi = num;
+		}
+	      else if (num != elf32xtensa_abi)
 		{
 		  *pmismatch = TRUE;
 		  *pmsg = "ABI does not match";
@@ -489,7 +505,7 @@ elf_xtensa_before_allocation (void)
 
       data = xmalloc (100);
       sprintf (data, "USE_ABSOLUTE_LITERALS=%d\nABI=%d\n",
-	       XSHAL_USE_ABSOLUTE_LITERALS, XSHAL_ABI);
+	       XSHAL_USE_ABSOLUTE_LITERALS, xtensa_abi_choice ());
       xtensa_info_size = strlen (data) + 1;
 
       /* Add enough null terminators to pad to a word boundary.  */
@@ -1920,20 +1936,29 @@ PARSE_AND_LIST_PROLOGUE='
 #define OPTION_OPT_SIZEOPT              (300)
 #define OPTION_LITERAL_MOVEMENT		(OPTION_OPT_SIZEOPT + 1)
 #define OPTION_NO_LITERAL_MOVEMENT	(OPTION_LITERAL_MOVEMENT + 1)
+#define OPTION_ABI_WINDOWED		(OPTION_NO_LITERAL_MOVEMENT + 1)
+#define OPTION_ABI_CALL0		(OPTION_ABI_WINDOWED + 1)
 extern int elf32xtensa_size_opt;
 extern int elf32xtensa_no_literal_movement;
+extern int elf32xtensa_abi;
 '
 
 PARSE_AND_LIST_LONGOPTS='
   { "size-opt", no_argument, NULL, OPTION_OPT_SIZEOPT},
   { "literal-movement", no_argument, NULL, OPTION_LITERAL_MOVEMENT},
   { "no-literal-movement", no_argument, NULL, OPTION_NO_LITERAL_MOVEMENT},
+  { "abi-windowed", no_argument, NULL, OPTION_ABI_WINDOWED},
+  { "abi-call0", no_argument, NULL, OPTION_ABI_CALL0},
 '
 
 PARSE_AND_LIST_OPTIONS='
   fprintf (file, _("\
   --size-opt                  When relaxing longcalls, prefer size\n\
                                 optimization over branch target alignment\n"));
+  fprintf (file, _("\
+  --abi-windowed              Choose windowed ABI for the output object\n"));
+  fprintf (file, _("\
+  --abi-call0                 Choose call0 ABI for the output object\n"));
 '
 
 PARSE_AND_LIST_ARGS_CASES='
@@ -1946,6 +1971,12 @@ PARSE_AND_LIST_ARGS_CASES='
     case OPTION_NO_LITERAL_MOVEMENT:
       elf32xtensa_no_literal_movement = 1;
       break;
+    case OPTION_ABI_WINDOWED:
+      elf32xtensa_abi = XTHAL_ABI_WINDOWED;
+      break;
+    case OPTION_ABI_CALL0:
+      elf32xtensa_abi = XTHAL_ABI_CALL0;
+      break;
 '
 
 # Replace some of the standard ELF functions with our own versions.
diff --git a/ld/ld.texi b/ld/ld.texi
index b89c1a5..ecdbf77 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -8565,6 +8565,17 @@ more than performance.  With this option, the linker will not insert
 no-ops or widen density instructions to preserve branch target
 alignment.  There may still be some cases where no-ops are required to
 preserve the correctness of the code.
+
+@item --abi-windowed
+@itemx --abi-call0
+Choose ABI for the output object and for the generated PLT code.
+PLT code inserted by the linker must match ABI of the output object
+because windowed and call0 ABI use incompatible function call
+conventions.
+Default ABI is chosen by the ABI tag in the @code{.xtensa.info} section
+of the first input object.
+A warning is issued if ABI tags of input objects do not match each other
+or the chosen output object ABI.
 @end table
 
 @ifclear GENERIC