nvptx: Handle '__builtin_stack_save()' in a well-behaved way for PTX "native" stacks...

	PR target/65181
	gcc/
	* config/nvptx/nvptx.md [!TARGET_SOFT_STACK] (save_stack_block):
	'define_expand'.
	gcc/testsuite/
	* gcc.target/nvptx/__builtin_stack_save___builtin_stack_restore-1.c:
	Adjust.

diff --git a/gcc/config/nvptx/nvptx.md b/gcc/config/nvptx/nvptx.md
index f77752a3f55361f776d77a92ed307c5e2a4e28e9..56cd25e77e45e8dbe324bb1fb2c0b94455450646 100644 (file)
--- a/gcc/config/nvptx/nvptx.md
+++ b/gcc/config/nvptx/nvptx.md
@@ -1687,12 +1687,28 @@
   return nvptx_output_set_softstack (REGNO (operands[0]));
 })
 
+(define_expand "save_stack_block"
+  [(match_operand 0 "register_operand" "")
+   (match_operand 1 "register_operand" "")]
+  "!TARGET_SOFT_STACK"
+{
+  /* The concept of a '%stack' pointer doesn't apply like this for
+     PTX "native" stacks.  GCC however occasionally synthesizes
+     '__builtin_stack_save ()', '__builtin_stack_restore ()', and isn't able to
+     optimize them all away.  Just submit a dummy -- user code shouldn't be
+     able to observe this.  */
+  emit_move_insn (operands[0], GEN_INT (0xdeadbeef));
+  DONE;
+})
+
 (define_expand "restore_stack_block"
   [(match_operand 0 "register_operand" "")
    (match_operand 1 "register_operand" "")]
   ""
 {
-  if (TARGET_SOFT_STACK)
+  if (!TARGET_SOFT_STACK)
+    ; /* See 'save_stack_block'.  */
+  else
     {
       emit_move_insn (operands[0], operands[1]);
       emit_insn (gen_set_softstack (Pmode, operands[0]));

diff --git a/gcc/testsuite/gcc.target/nvptx/__builtin_stack_save___builtin_stack_restore-1.c b/gcc/testsuite/gcc.target/nvptx/__builtin_stack_save___builtin_stack_restore-1.c
index 294014dae1db7b373407abe0d848a2581edb5c11..35a879fd597351407ef959ef84e06ad1e9eed0ba 100644 (file)
--- a/gcc/testsuite/gcc.target/nvptx/__builtin_stack_save___builtin_stack_restore-1.c
+++ b/gcc/testsuite/gcc.target/nvptx/__builtin_stack_save___builtin_stack_restore-1.c
@@ -1,7 +1,6 @@
 /* Document what we do for '__builtin_stack_save()', '__builtin_stack_restore()'.  */
 
-/* { dg-do compile }
-   TODO We can't 'assemble' this -- it's invalid PTX code.  */
+/* { dg-do assemble } */
 /* { dg-options {-O3 -mno-soft-stack} } */
 /* { dg-additional-options -save-temps } */
 /* { dg-final { check-function-bodies {** } {} } } */
@@ -10,8 +9,10 @@ void *p;
 
 void f(void)
 {
+  // 0xdeadbeef
   p = __builtin_stack_save();
   asm volatile ("" : : : "memory");
+  // no-op
   __builtin_stack_restore(p);
   asm volatile ("" : : : "memory");
 }
@@ -19,14 +20,8 @@ void f(void)
 ** f:
 ** \.visible \.func f
 ** {
-**             st\.global\.u64 \[p\], %stack;
+**     \.reg\.u64 (%r[0-9]+);
+**             mov\.u64        \1, 3735928559;
+**             st\.global\.u64 \[p\], \1;
 **     ret;
 */
-
-/* The concept of a '%stack' pointer doesn't apply like this for
-   '-mno-soft-stack': PTX "native" stacks (TODO).
-
-   { dg-final { scan-assembler-not {%stack} { xfail *-*-* } } } */
-
-/* As these are an internal-use built-in function, we don't bother with
-   emitting proper error diagnostics.  */