[newlib-cygwin] nvptx: Emulate clock and other machine stubs.

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=6bb96d13a2d7f652b614850eb341905031101d32

commit 6bb96d13a2d7f652b614850eb341905031101d32
Author: Roger Sayle <roger@nextmovesoftware.com>
Date:   Tue Aug 24 17:24:19 2021 +0100

    nvptx: Emulate clock and other machine stubs.
    
    This patch to the libc/machine/nvptx port of newlib implements an
    approximation of "clock" and provides some additional stub routines.
    These changes not only reduce the number of (link) failures in the GCC
    testsuite when targeting nvptx-none, but also allow the NIST scimark4
    benchmark to compile and run without modification.
    
    newlib already contains support for backends to provide their own
    clock implementations via -DCLOCK_PROVIDED.  That functionality is
    used here to return an approximate elapsed time based on the NVidia
    GPU's clock64 cycle counter.  Although not great, this is better than
    the current behaviour of link error from the unresolved symbol
    _times_r.
    
    The other part of the patch is to add a small number of stub functions
    to nvptx's misc.c.  Adding isatty, for example, resolves linking
    problems in libc from the dependency in __smakebuf_r, and the sync
    stub, for example, fixes the failure with GCC's
    testsuite/gfortran.dg/ISO_Fortran_binding_14.f90 [which simply tests
    that gfortran can call a/any C function].
    
    newlib/
            configure.host: Add -DCLOCK_PROVIDED to newlib_cflags on nvptx*.
    
    newlib/libc/machine/nvptx
            Makefile.am: Add clock.c to lib_a_SOURCES.
            clock.c: New source file to implement/approximate clock().
            misc.c: Add stubs for fstat, isatty, open, sync and unlink.

Diff:
---
 newlib/configure.host                 |  2 +-
 newlib/libc/machine/nvptx/Makefile.am |  2 +-
 newlib/libc/machine/nvptx/Makefile.in | 11 +++++++++--
 newlib/libc/machine/nvptx/clock.c     | 18 ++++++++++++++++++
 newlib/libc/machine/nvptx/configure   |  2 ++
 newlib/libc/machine/nvptx/misc.c      | 25 +++++++++++++++++++++++++
 6 files changed, 56 insertions(+), 4 deletions(-)

diff --git a/newlib/configure.host b/newlib/configure.host
index 4ac53342a..ef481ff52 100644
--- a/newlib/configure.host
+++ b/newlib/configure.host
@@ -289,7 +289,7 @@ case "${host_cpu}" in
 	;;
   nvptx*)
 	machine_dir=nvptx
-	newlib_cflags="${newlib_cflags} -DMALLOC_PROVIDED"
+	newlib_cflags="${newlib_cflags} -DCLOCK_PROVIDED -DMALLOC_PROVIDED"
 	;;
   or1k*|or1knd*)
 	machine_dir=or1k
diff --git a/newlib/libc/machine/nvptx/Makefile.am b/newlib/libc/machine/nvptx/Makefile.am
index 66664d3c2..b0d4c7822 100644
--- a/newlib/libc/machine/nvptx/Makefile.am
+++ b/newlib/libc/machine/nvptx/Makefile.am
@@ -10,7 +10,7 @@ noinst_LIBRARIES = lib.a
 
 lib_a_SOURCES = calloc.c callocr.c malloc.c mallocr.c realloc.c reallocr.c \
 		free.c write.c assert.c puts.c putchar.c printf.c abort.c \
-		exit.c misc.c
+		exit.c misc.c clock.c
 lib_a_CFLAGS = $(AM_CFLAGS)
 
 ACLOCAL_AMFLAGS = -I ../../.. -I ../../../..
diff --git a/newlib/libc/machine/nvptx/Makefile.in b/newlib/libc/machine/nvptx/Makefile.in
index 75256b352..a01e09725 100644
--- a/newlib/libc/machine/nvptx/Makefile.in
+++ b/newlib/libc/machine/nvptx/Makefile.in
@@ -76,7 +76,7 @@ am_lib_a_OBJECTS = lib_a-calloc.$(OBJEXT) lib_a-callocr.$(OBJEXT) \
 	lib_a-assert.$(OBJEXT) lib_a-puts.$(OBJEXT) \
 	lib_a-putchar.$(OBJEXT) lib_a-printf.$(OBJEXT) \
 	lib_a-abort.$(OBJEXT) lib_a-exit.$(OBJEXT) \
-	lib_a-misc.$(OBJEXT)
+	lib_a-misc.$(OBJEXT) lib_a-clock.$(OBJEXT)
 lib_a_OBJECTS = $(am_lib_a_OBJECTS)
 DEFAULT_INCLUDES = -I.@am__isrc@
 depcomp =
@@ -188,6 +188,7 @@ prefix = @prefix@
 program_transform_name = @program_transform_name@
 psdir = @psdir@
 sbindir = @sbindir@
+shared_machine_dir = @shared_machine_dir@
 sharedstatedir = @sharedstatedir@
 srcdir = @srcdir@
 sys_dir = @sys_dir@
@@ -202,7 +203,7 @@ AM_CCASFLAGS = $(INCLUDES)
 noinst_LIBRARIES = lib.a
 lib_a_SOURCES = calloc.c callocr.c malloc.c mallocr.c realloc.c reallocr.c \
 		free.c write.c assert.c puts.c putchar.c printf.c abort.c \
-		exit.c misc.c
+		exit.c misc.c clock.c
 
 lib_a_CFLAGS = $(AM_CFLAGS)
 ACLOCAL_AMFLAGS = -I ../../.. -I ../../../..
@@ -355,6 +356,12 @@ lib_a-misc.o: misc.c
 lib_a-misc.obj: misc.c
 	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-misc.obj `if test -f 'misc.c'; then $(CYGPATH_W) 'misc.c'; else $(CYGPATH_W) '$(srcdir)/misc.c'; fi`
 
+lib_a-clock.o: clock.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-clock.o `test -f 'clock.c' || echo '$(srcdir)/'`clock.c
+
+lib_a-clock.obj: clock.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-clock.obj `if test -f 'clock.c'; then $(CYGPATH_W) 'clock.c'; else $(CYGPATH_W) '$(srcdir)/clock.c'; fi`
+
 ID: $(HEADERS) $(SOURCES) $(LISP) $(TAGS_FILES)
 	list='$(SOURCES) $(HEADERS) $(LISP) $(TAGS_FILES)'; \
 	unique=`for i in $$list; do \
diff --git a/newlib/libc/machine/nvptx/clock.c b/newlib/libc/machine/nvptx/clock.c
new file mode 100644
index 000000000..1ad69f1ea
--- /dev/null
+++ b/newlib/libc/machine/nvptx/clock.c
@@ -0,0 +1,18 @@
+/* clock.c
+ * Support file for nvptx in newlib.
+ */
+#include <time.h>
+
+clock_t
+clock ()
+{
+  unsigned long long now;
+#if __PTX_SM__ >= 310
+  asm volatile("mov.u64 %0, %%globaltimer;" : "=r"(now));
+  return now/((1000000000ull)/CLOCKS_PER_SEC);
+#else
+  asm volatile("mov.u64 %0, %%clock64;" : "=r"(now));
+  // Assume a GPU base clock frequency of 1250MHz.
+  return now/((1250000000ull)/CLOCKS_PER_SEC);
+#endif
+}
diff --git a/newlib/libc/machine/nvptx/configure b/newlib/libc/machine/nvptx/configure
index 282728efe..29d16d924 100644
--- a/newlib/libc/machine/nvptx/configure
+++ b/newlib/libc/machine/nvptx/configure
@@ -565,6 +565,7 @@ ac_unique_file="Makefile.am"
 ac_subst_vars='LTLIBOBJS
 LIBOBJS
 sys_dir
+shared_machine_dir
 machine_dir
 libm_machine_dir
 lpfx
@@ -3428,6 +3429,7 @@ OBJEXT=${oext}
 
 
 
+
 ac_config_files="$ac_config_files Makefile"
 
 cat >confcache <<\_ACEOF
diff --git a/newlib/libc/machine/nvptx/misc.c b/newlib/libc/machine/nvptx/misc.c
index ed1bc3478..ef76eaae1 100644
--- a/newlib/libc/machine/nvptx/misc.c
+++ b/newlib/libc/machine/nvptx/misc.c
@@ -15,6 +15,7 @@
 
 #include <errno.h>
 #include <sys/types.h>
+#include <sys/stat.h>
 #undef errno
 extern int errno;
 
@@ -23,12 +24,36 @@ close(int fd) {
   return -1;
 }
 
+int
+fstat (int fd, struct stat *buf) {
+  return -1;
+}
+
+int
+isatty (int fd) {
+  return fd == 1;
+}
+
 off_t
 lseek(int fd, off_t offset, int whence) {
   return 0;
 }
 
+int
+open (const char *pathname, int flags, ...) {
+  return -1;
+}
+
 int
 read(int fd, void *buf, size_t count) {
   return 0;
 }
+
+void
+sync (void) {
+}
+
+int
+unlink (const char *pathname) {
+  return -1;
+}