New Makefile target `regen-ulps'.

The wiki "Regeneration" page has this to say about update ULPs.

"The libm-test-ulps files are semiautomatically updated. To
update an ulps baseline, run each of the failing tests (test-float,
 test-double, etc.) with -u; this will generate a file called ULPs;
concatenate each of those files with the existing libm-test-ulps
file, after removing any entries for particularly huge numbers of
ulps that you do not want to mark as expected. Then run
gen-libm-test.pl -n -u FILE where FILE is the concatenated file
produced in the previous step. This generates a file called
NewUlps which is the new sorted version of libm-test-ulps."

The same information is listed in math/README.libm-test, and is a
lot of manual work that you often want to run over-and-over again
while working on a particular test.

The `regen-ulps' convenience target does this automatically for
developers.

We strictly assume the source tree is readonly and add a
new --output-dir option to libm-test.inc to allow for writing
out ULPs to $(objpfx).

When run the new target does the following:
* Starts with the baseline ULPs file.
* Runs each of the libm math tests with -u.
* Adds new changes seen with -u to the baseline.
* Sorts and prepares the test output with gen-libm-test.pl.
* Leaves math/NewUlps in your build tree to copy to your source
  tree, cleanup, and checkin.

The math test documentation in math/README.libm-test is updated
document the new Makefile target.

---

2013-04-06  Carlos O'Donell  <carlos@redhat.com>

	* Makefile.in (regen-ulps): New target.
	* math/Makefile [ifneq (no,$(PERL)]: Declare regen-ulps with .PHONY.
	[ifneq (no,$(PERL)] (run-regen-ulps): New variable.
	[ifneq (no,$(PERL)] (regen-ulps): New target.
	[ifeq (no,$(PERL)] (regen-ulps): New target.
	* math/libm-test.inc (ulps_file_name): Define.
	(output_dir): New variable.
	(options): Add "output-dir" option.
	(parse_opt): Handle 'o' case.
	(main): If output_dir is non-NULL use it as a prefix
	otherwise use "".
	* math/README.libm-test: Update `How can I generate "libm-test-ulps"?'

3 files changed, 78 insertions, 19 deletions

diff --git a/math/Makefile b/math/Makefile
index f396ba2..ee5b582 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -150,6 +150,33 @@ extra-objs += libieee.a ieee-math.o
 
 include ../Rules
 
+ifneq (no,$(PERL))
+# Run the math programs to automatically generate ULPs files.
+.PHONY: regen-ulps
+
+run-regen-ulps = $(test-wrapper-env) \
+	    GCONV_PATH=$(common-objpfx)iconvdata LC_ALL=C \
+	    $($*-ENV) $(run-via-rtld-prefix) $${run}
+
+regen-ulps: $(addprefix $(objpfx),$(libm-tests))
+	rm -f $(objpfx)ULPs; rm -f $(objpfx)NewUlps; \
+	cp $(ulps-file) $(objpfx)libm-test-ulps; \
+	for run in $^; do \
+	  echo "Regenerating ULPs for $${run}"; \
+	  $(run-regen-ulps) -u -o $(objpfx); \
+	  cat $(objpfx)ULPs >> $(objpfx)libm-test-ulps; \
+	  rm $(objpfx)ULPs; \
+	done; \
+	$(PERL) gen-libm-test.pl -o $(objpfx) -n -u $(objpfx)libm-test-ulps; \
+	echo "Automatic regeneration of ULPs complete."; \
+	echo "Difference between the current baseline and the new baseline is:";\
+	diff -urN $(ulps-file) $(objpfx)NewUlps; \
+	echo "Copy $(objpfx)NewUlps to $(ulps-file) (relative to source)."
+else
+regen-ulps:
+	@echo "Automatic regeneration of ULPs requires perl."; \
+	exit 1;
+endif
 
 # The generated sysd-rules file defines rules like this for sources
 # coming from sysdeps/ directories.  These rules find the generic sources.
diff --git a/math/README.libm-test b/math/README.libm-test
index 7a46155..2929499 100644
--- a/math/README.libm-test
+++ b/math/README.libm-test
@@ -39,24 +39,33 @@ platform specific sysdep directory.
 How can I generate "libm-test-ulps"?
 ====================================
 
-The test drivers have an option "-u" to output an unsorted list of all
-epsilons that the functions have.  The output can be read in directly
-but it's better to pretty print it first.  "gen-libm-test.pl"  has an option
-to generate a pretty-printed and sorted new ULPs file from the output
-of the test drivers.
-
-To generate a new "libm-test-ulps" file, first remove "ULPs" file in the
-current directory, then you can execute for example:
-test-double -u --ignore-max-ulp=yes
+To automatically generate a new "libm-test-ulps" run "make regen-ulps".
+This generates the file "math/NewUlps" in the build directory.  The file
+contains the sorted results of all the tests.  You can use the "NewUlps"
+file as the machine's updated "libm-test-ulps" file.  Copy "NewUlps" to
+"libm-test-ulps" in the appropriate machine sysdep directory.  Verify
+the changes, post your patch, and check it in after review.
+
+To manually generate a new "libm-test-ulps" file, first remove "ULPs"
+file in the current directory, then you can execute for example:
+  /build/elf/ld.so --library--path /build/:/build/elf:/build/math \
+    test-double -u --ignore-max-ulp=yes
 This generates a file "ULPs" with all double ULPs in it, ignoring any
-previous calculated ULPs.
-Now generate the ULPs for all other formats, the tests will be appending
-the data to the "ULPs" file.  As final step run "gen-libm-test.pl" with the
-file as input and ask to generate a pretty printed output in the file "NewUlps":
+previously calculated ULPs, and running with the newly built dynamic
+loader and math library (assumes you didn't install your build).  Now
+generate the ULPs for all other formats, the tests will be appending the
+data to the "ULPs" file.  As final step run "gen-libm-test.pl" with the
+file as input and ask to generate a pretty printed output in the file
+"NewUlps":
   gen-libm-test.pl -u ULPs -n
-
-Now you can rename "NewUlps" to "libm-test-ulps" and move it into
-sysdeps.
+Copy "NewUlps" to "libm-test-ulps" in the appropriate machine sysdep
+directory.
+
+Note that the test drivers have an option "-u" to output an unsorted
+list of all epsilons that the functions have.  The output can be read
+in directly but it's better to pretty print it first.
+"gen-libm-test.pl" has an option to generate a pretty-printed and
+sorted new ULPs file from the output of the test drivers.
 
 Contents of libm-test-ulps
 ==========================
diff --git a/math/libm-test.inc b/math/libm-test.inc
index 92fa6a2..78d2107 100644
--- a/math/libm-test.inc
+++ b/math/libm-test.inc
@@ -210,8 +210,10 @@
 #define M_PI_LOG10El		M_PIl * M_LOG10El
 #define M_SQRT_2_2		0.70710678118654752440084436210484903L /* sqrt (2) / 2 */
 
-static FILE *ulps_file;	/* File to document difference.  */
-static int output_ulps;	/* Should ulps printed?  */
+#define ulps_file_name "ULPs"	/* Name of the ULPs file.  */
+static FILE *ulps_file;		/* File to document difference.  */
+static int output_ulps;		/* Should ulps printed?  */
+static char *output_dir;	/* Directory where generated files will be written.  */
 
 static int noErrors;	/* number of errors */
 static int noTests;	/* number of tests (without testing exceptions) */
@@ -12985,6 +12987,8 @@ static const struct argp_option options[] =
     "Don't output results of functions invocations"},
   { "ignore-max-ulp", 'i', "yes/no", 0,
     "Ignore given maximal errors"},
+  { "output-dir", 'o', "DIR", 0,
+    "Directory where generated files will be placed"},
   { NULL, 0, NULL, 0, NULL }
 };
 
@@ -13016,6 +13020,13 @@ parse_opt (int key, char *arg, struct argp_state *state)
       else if (strcmp (arg, "no") == 0)
 	ignore_max_ulp = 0;
       break;
+    case 'o':
+      output_dir = (char *) malloc (strlen (arg) + 1);
+      if (output_dir != NULL)
+	strcpy (output_dir, arg);
+      else
+        return errno;
+      break;
     case 'p':
       output_points = 0;
       break;
@@ -13065,11 +13076,14 @@ main (int argc, char **argv)
 {
 
   int remaining;
+  char *ulps_file_path;
+  size_t dir_len = 0;
 
   verbose = 1;
   output_ulps = 0;
   output_max_error = 1;
   output_points = 1;
+  output_dir = NULL;
   /* XXX set to 0 for releases.  */
   ignore_max_ulp = 0;
 
@@ -13085,7 +13099,16 @@ main (int argc, char **argv)
 
   if (output_ulps)
     {
-      ulps_file = fopen ("ULPs", "a");
+      if (output_dir != NULL)
+	dir_len = strlen (output_dir);
+      ulps_file_path = (char *) malloc (dir_len + strlen (ulps_file_name) + 1);
+      if (ulps_file_path == NULL)
+        {
+	  perror ("can't allocate path for `ULPs' file: ");
+	  exit (1);
+        }
+      sprintf (ulps_file_path, "%s%s", output_dir == NULL ? "" : output_dir, ulps_file_name);
+      ulps_file = fopen (ulps_file_path, "a");
       if (ulps_file == NULL)
 	{
 	  perror ("can't open file `ULPs' for writing: ");