[Committed] S/390: Deprecate g5 and g6 CPU levels.

[Andreas Krebbel <krebbel at linux dot vnet dot ibm dot com>]

Hi,

I've committed the attached patch which emits warnings whenever g5 or
g6 are being used explicitely as -march/-mtune parameters.  These
machines can only be seen in museums nowadays and have no practical
use anymore.  They do not support the z/Architecture mode required for
64 bit. The Linux kernel does not support them either.

In the GCC back-end the code to support these old CPU levels is
particularly annoying since they do not provide long relative
addressing (larl and brasl).  Hence much of the literal pool special
handling exists only because of supporting these CPUs. I would like to
get rid of this someday in the future.

Note: This does not remove support for -mesa yet. One can still
compile code targetting kernels running in ESA mode.  Since this isn't
supported by the kernel anymore the long term target of course is to
get rid of this as well. But unfortunately we still have that problem
with the inline asms which needs to be addressed first ...

Committed to mainline.

Bye,

-Andreas-

gcc/ChangeLog:

2015-12-18  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* config/s390/driver-native.c (s390_host_detect_local_cpu): Pick
	z900 -march -mtune even on g5 and g6 machines.
	* config/s390/s390.c (s390_option_override_internal): New argument
	to distingiush between options and target attributes.  Emit
	deprecation warning for g5 and g6 arch/tune options.
	(s390_option_override): Set new s390_option_override_internal
	argument to true.
	(s390_valid_target_attribute_tree): Set new
	s390_option_override_internal argument to false.
	* config/s390/s390.h: Default to z900 in the driver.
	* doc/invoke.texi: Document the deprecation of g5 and g6.

gcc/testsuite/ChangeLog:

2015-12-18  Andreas Krebbel  <krebbel@linux.vnet.ibm.com>

	* gcc.target/s390/hotpatch-8.c: Add -Wno-deprecated to options.
	* gcc.target/s390/hotpatch-9.c: Likewise.


diff --git a/gcc/config/s390/driver-native.c b/gcc/config/s390/driver-native.c
index 5f7fe0a..08ec85e 100644
--- a/gcc/config/s390/driver-native.c
+++ b/gcc/config/s390/driver-native.c
@@ -84,9 +84,8 @@ s390_host_detect_local_cpu (int argc, const char **argv)
 	  machine_id = strtol (p, NULL, 16);
 	  switch (machine_id)
 	    {
+	      /* g5 and g6 default to z900 */
 	    case 0x9672:
-	      cpu = "g5";
-	      break;
 	    case 0x2064:
 	    case 0x2066:
 	      cpu = "z900";
diff --git a/gcc/config/s390/s390.c b/gcc/config/s390/s390.c
index bc6f05b..2a42818 100644
--- a/gcc/config/s390/s390.c
+++ b/gcc/config/s390/s390.c
@@ -13569,9 +13569,27 @@ s390_function_specific_restore (struct gcc_options *opts,
 }
 
 static void
-s390_option_override_internal (struct gcc_options *opts,
+s390_option_override_internal (bool main_args_p,
+			       struct gcc_options *opts,
 			       const struct gcc_options *opts_set)
 {
+  const char *prefix;
+  const char *suffix;
+
+  /* Set up prefix/suffix so the error messages refer to either the command
+     line argument, or the attribute(target).  */
+  if (main_args_p)
+    {
+      prefix = "-m";
+      suffix = "";
+    }
+  else
+    {
+      prefix = "option(\"";
+      suffix = "\")";
+    }
+
+
   /* Architecture mode defaults according to ABI.  */
   if (!(opts_set->x_target_flags & MASK_ZARCH))
     {
@@ -13583,13 +13601,26 @@ s390_option_override_internal (struct gcc_options *opts,
 
   /* Set the march default in case it hasn't been specified on cmdline.  */
   if (!opts_set->x_s390_arch)
-    opts->x_s390_arch = TARGET_ZARCH_P (opts->x_target_flags)
-      ? PROCESSOR_2064_Z900 : PROCESSOR_9672_G5;
+    opts->x_s390_arch = PROCESSOR_2064_Z900;
+  else if (opts->x_s390_arch == PROCESSOR_9672_G5
+	   || opts->x_s390_arch == PROCESSOR_9672_G6)
+    warning (OPT_Wdeprecated, "%sarch=%s%s is deprecated and will be removed "
+	     "in future releases; use at least %sarch=z900%s",
+	     prefix, opts->x_s390_arch == PROCESSOR_9672_G5 ? "g5" : "g6",
+	     suffix, prefix, suffix);
+
   opts->x_s390_arch_flags = processor_flags_table[(int) opts->x_s390_arch];
 
   /* Determine processor to tune for.  */
   if (!opts_set->x_s390_tune)
     opts->x_s390_tune = opts->x_s390_arch;
+  else if (opts->x_s390_tune == PROCESSOR_9672_G5
+	   || opts->x_s390_tune == PROCESSOR_9672_G6)
+    warning (OPT_Wdeprecated, "%stune=%s%s is deprecated and will be removed "
+	     "in future releases; use at least %stune=z900%s",
+	     prefix, opts->x_s390_tune == PROCESSOR_9672_G5 ? "g5" : "g6",
+	     suffix, prefix, suffix);
+
   opts->x_s390_tune_flags = processor_flags_table[opts->x_s390_tune];
 
   /* Sanity checks.  */
@@ -13800,7 +13831,7 @@ s390_option_override (void)
   /* Set up function hooks.  */
   init_machine_status = s390_init_machine_status;
 
-  s390_option_override_internal (&global_options, &global_options_set);
+  s390_option_override_internal (true, &global_options, &global_options_set);
 
   /* Save the initial options in case the user does function specific
      options.  */
@@ -14102,7 +14133,7 @@ s390_valid_target_attribute_tree (tree args,
 	dest[i] |= src[i];
 
       /* Do any overrides, such as arch=xxx, or tune=xxx support.  */
-      s390_option_override_internal (opts, &new_opts_set);
+      s390_option_override_internal (false, opts, &new_opts_set);
       /* Save the current options unless we are validating options for
 	 #pragma.  */
       t = build_target_option_node (opts);
diff --git a/gcc/config/s390/s390.h b/gcc/config/s390/s390.h
index 52ed7a4..603e638 100644
--- a/gcc/config/s390/s390.h
+++ b/gcc/config/s390/s390.h
@@ -214,7 +214,7 @@ extern const char *s390_host_detect_local_cpu (int argc, const char **argv);
   MARCH_MTUNE_NATIVE_SPECS,					\
   "%{!m31:%{!m64:-m" S390_TARGET_BITS_STRING "}}",		\
   "%{!mesa:%{!mzarch:%{m31:-mesa}%{m64:-mzarch}}}",		\
-  "%{!march=*:%{mesa:-march=g5}%{mzarch:-march=z900}}"
+  "%{!march=*:-march=z900}"
 
 /* Constants needed to control the TEST DATA CLASS (TDC) instruction.  */
 #define S390_TDC_POSITIVE_ZERO                     (1 << 11)
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 9b3e2fe..346e40b 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -20893,14 +20893,12 @@ The default is to not print debug information.
 
 @item -march=@var{cpu-type}
 @opindex march
-Generate code that runs on @var{cpu-type}, which is the name of a system
-representing a certain processor type.  Possible values for
-@var{cpu-type} are @samp{g5}, @samp{g6}, @samp{z900}, @samp{z990},
-@samp{z9-109}, @samp{z9-ec}, @samp{z10},  @samp{z196}, @samp{zEC12},
-and @samp{z13}.
-When generating code using the instructions available on z/Architecture,
-the default is @option{-march=z900}.  Otherwise, the default is
-@option{-march=g5}.
+Generate code that runs on @var{cpu-type}, which is the name of a
+system representing a certain processor type.  Possible values for
+@var{cpu-type} are @samp{z900}, @samp{z990}, @samp{z9-109},
+@samp{z9-ec}, @samp{z10}, @samp{z196}, @samp{zEC12}, and @samp{z13}.
+The default is @option{-march=z900}.  @samp{g5} and @samp{g6} are
+deprecated and will be removed with future releases.
 
 @item -mtune=@var{cpu-type}
 @opindex mtune
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-8.c b/gcc/testsuite/gcc.target/s390/hotpatch-8.c
index 1ea3160..c5b71a5 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-8.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-8.c
@@ -1,7 +1,7 @@
 /* Functional tests for the function hotpatching feature.  */
 
 /* { dg-do compile { target { ! lp64 } } } */
-/* { dg-options "-mesa -march=g5 -mhotpatch=0,3" } */
+/* { dg-options "-mesa -march=g5 -Wno-deprecated -mhotpatch=0,3" } */
 
 #include <stdio.h>
 
diff --git a/gcc/testsuite/gcc.target/s390/hotpatch-9.c b/gcc/testsuite/gcc.target/s390/hotpatch-9.c
index e30f276..9ccc8fd 100644
--- a/gcc/testsuite/gcc.target/s390/hotpatch-9.c
+++ b/gcc/testsuite/gcc.target/s390/hotpatch-9.c
@@ -1,7 +1,7 @@
 /* Functional tests for the function hotpatching feature.  */
 
 /* { dg-do compile { target { ! lp64 } } } */
-/* { dg-options "-mesa -march=g5 -mhotpatch=0,4" } */
+/* { dg-options "-mesa -march=g5 -Wno-deprecated -mhotpatch=0,4" } */
 
 #include <stdio.h>