[newlib-cygwin] amdgcn: Replace asm("s8") by __builtin_gcn_kernarg_ptr if existing

[Corinna Vinschen <corinna@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=newlib-cygwin.git;h=b9898fc99379b35e41311012c4a3fe5b60305a3d

commit b9898fc99379b35e41311012c4a3fe5b60305a3d
Author: Tobias Burnus <tobias@codesourcery.com>
Date:   Fri Nov 18 09:50:20 2022 +0100

    amdgcn: Replace asm("s8") by __builtin_gcn_kernarg_ptr if existing
    
    Check whether __builtin_gcn_kernarg_ptr is available and, if it is,
    call it instead using the hard-coded 'asm("s8")' in:
    * newlib/libc/machine/amdgcn/exit-value.h (exit_with_int)
    * newlib/libc/machine/amdgcn/mlock.c (sbrk)
    * newlib/libc/sys/amdgcn/write.c (write)
    
     newlib/libc/machine/amdgcn/exit-value.h |  6 ++++++
     newlib/libc/machine/amdgcn/mlock.c      | 10 +++++++---
     newlib/libc/sys/amdgcn/write.c          |  4 ++++
     3 files changed, 17 insertions(+), 3 deletions(-)

Diff:
---
 newlib/libc/machine/amdgcn/exit-value.h |  6 ++++++
 newlib/libc/machine/amdgcn/mlock.c      | 10 +++++++---
 newlib/libc/sys/amdgcn/write.c          |  4 ++++
 3 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/newlib/libc/machine/amdgcn/exit-value.h b/newlib/libc/machine/amdgcn/exit-value.h
index 6e88625b7..7aa2508bb 100644
--- a/newlib/libc/machine/amdgcn/exit-value.h
+++ b/newlib/libc/machine/amdgcn/exit-value.h
@@ -21,8 +21,14 @@ exit_with_int (int val)
 {
   /* Write the exit value to the conventional place.  */
   int *return_value;
+#if defined(__has_builtin) && __has_builtin(__builtin_gcn_kernarg_ptr)
+  asm ("s_load_dwordx2	%0, %1, 16 glc\n\t"
+       "s_waitcnt	0"
+       : "=Sg"(return_value) : "r"(__builtin_gcn_kernarg_ptr()));
+#else
   asm ("s_load_dwordx2	%0, s[8:9], 16 glc\n\t"
        "s_waitcnt	0" : "=Sg"(return_value));
+#endif
   *return_value = val;
 
   /* Terminate the current kernel.  */
diff --git a/newlib/libc/machine/amdgcn/mlock.c b/newlib/libc/machine/amdgcn/mlock.c
index 4848c978c..fbc4944e6 100644
--- a/newlib/libc/machine/amdgcn/mlock.c
+++ b/newlib/libc/machine/amdgcn/mlock.c
@@ -39,11 +39,15 @@ sbrk (ptrdiff_t nbytes)
 {
   if (__heap_ptr == (char *)-1)
     {
-      /* Find the heap from kernargs.
-         The kernargs pointer is in s[8:9].
-	 This will break if the enable_sgpr_* flags are ever changed.  */
+      /* Find the heap from kernargs.  */
       char *kernargs;
+#if defined(__has_builtin) && __has_builtin(__builtin_gcn_kernarg_ptr)
+      kernargs = __builtin_gcn_kernarg_ptr ();
+#else
+      /* The kernargs pointer is in s[8:9].
+	 This will break if the enable_sgpr_* flags are ever changed.  */
       asm ("s_mov_b64 %0, s[8:9]" : "=Sg"(kernargs));
+#endif
 
       /* The heap data is at kernargs[3].  */
       struct heap *heap = *(struct heap **)(kernargs + 24);
diff --git a/newlib/libc/sys/amdgcn/write.c b/newlib/libc/sys/amdgcn/write.c
index 9c0d2a968..39e28c1e6 100644
--- a/newlib/libc/sys/amdgcn/write.c
+++ b/newlib/libc/sys/amdgcn/write.c
@@ -56,7 +56,11 @@ _READ_WRITE_RETURN_TYPE write (int fd, const void *buf, size_t count)
     }
 
   /* The output data is at ((void*)kernargs)[2].  */
+#if defined(__has_builtin) && __has_builtin(__builtin_gcn_kernarg_ptr)
+  register void **kernargs = __builtin_gcn_kernarg_ptr ();
+#else
   register void **kernargs asm("s8");
+#endif
   struct output *data = (struct output *)kernargs[2];
 
   /* Each output slot allows 256 bytes, so reserve as many as we need. */