[nvptx] Fix .local atomic regressions

In PR target/104364, two problems were reported:
- in muniform-simt mode, an atom.cas insn is no longer executed in the
  "master lane" only.
- in msoft-stack mode, an __atomic_compare_exchange_n on stack memory is
  translated assuming it accesses local memory, while that's not the case.

Fix these by:
- ensuring that all insns with atomic attribute are also predicable, such
  that the validate_change in nvptx_reorg_uniform_simt will succeed, and
  asserting that it does, and
- guarding the local atomics implementation with a new function
  nvptx_mem_local_p that correctly handles msoft-stack.

Tested on x86_64 with nvptx accelerator.

gcc/ChangeLog:

2022-02-04  Tom de Vries  <tdevries@suse.de>

	PR target/104364
	* config/nvptx/nvptx-protos.h (nvptx_mem_local_p): Declare.
	* config/nvptx/nvptx.cc (nvptx_reorg_uniform_simt): Assert that
	change is validated.
	(nvptx_mem_local_p): New function.
	* config/nvptx/nvptx.md: Use nvptx_mem_local_p.
	(define_c_enum "unspecv"): Add UNSPECV_CAS_LOCAL.
	(define_insn "atomic_compare_and_swap<mode>_1_local"): New
	non-atomic, non-predicable define_insn, factored out of ...
	(define_insn "atomic_compare_and_swap<mode>_1"): ... here.
	Make predicable again.
	(define_expand "atomic_compare_and_swap<mode>"): Use
	atomic_compare_and_swap<mode>_1_local.

gcc/testsuite/ChangeLog:

2022-02-04  Tom de Vries  <tdevries@suse.de>

	PR target/104364
	* gcc.target/nvptx/softstack-2.c: New test.
	* gcc.target/nvptx/uniform-simt-1.c: New test.

1 files changed, 24 insertions, 1 deletions

diff --git a/gcc/config/nvptx/nvptx.cc b/gcc/config/nvptx/nvptx.cc
index b3bb97c..2a69492 100644
--- a/gcc/config/nvptx/nvptx.cc
+++ b/gcc/config/nvptx/nvptx.cc
@@ -3150,7 +3150,8 @@ nvptx_reorg_uniform_simt ()
       rtx pred = nvptx_get_unisimt_predicate ();
       pred = gen_rtx_NE (BImode, pred, const0_rtx);
       pat = gen_rtx_COND_EXEC (VOIDmode, pred, pat);
-      validate_change (insn, &PATTERN (insn), pat, false);
+      bool changed_p = validate_change (insn, &PATTERN (insn), pat, false);
+      gcc_assert (changed_p);
     }
 }
 
@@ -6894,6 +6895,28 @@ nvptx_libc_has_function (enum function_class fn_class, tree type)
   return default_libc_has_function (fn_class, type);
 }
 
+bool
+nvptx_mem_local_p (rtx mem)
+{
+  gcc_assert (GET_CODE (mem) == MEM);
+
+  struct address_info info;
+  decompose_mem_address (&info, mem);
+
+  if (info.base != NULL && REG_P (*info.base)
+      && REGNO_PTR_FRAME_P (REGNO (*info.base)))
+    {
+      if (TARGET_SOFT_STACK)
+	{
+	  /* Frame-related doesn't mean local.  */
+	}
+      else
+	return true;
+    }
+
+  return false;
+}
+
 #undef TARGET_OPTION_OVERRIDE
 #define TARGET_OPTION_OVERRIDE nvptx_option_override