[gcc r14-8685] GCN, RDNA 3: Adjust 'sync_compare_and_swap<mode>_lds_insn'

[gcc r14-8685] GCN, RDNA 3: Adjust 'sync_compare_and_swap<mode>_lds_insn'

[Thomas Schwinge]

https://gcc.gnu.org/g:6c2a40f4f4577f5d0f7bd1cfda48a5701b75744c

commit r14-8685-g6c2a40f4f4577f5d0f7bd1cfda48a5701b75744c
Author: Thomas Schwinge <tschwinge@baylibre.com>
Date:   Wed Jan 31 10:19:00 2024 +0100

    GCN, RDNA 3: Adjust 'sync_compare_and_swap<mode>_lds_insn'
    
    For OpenACC/GCN '-march=gfx1100', a lot of libgomp OpenACC test cases FAIL:
    
        /tmp/ccGfLJ8a.mkoffload.2.s:406:2: error: instruction not supported on this GPU
                ds_cmpst_rtn_b32 v0, v0, v4, v3
                ^
    
    In RDNA 3, 'ds_cmpst_[...]' has been replaced by 'ds_cmpstore_[...]', and the
    notes for 'ds_cmpst_[...]' in pre-RDNA 3 ISA manuals:
    
        Caution, the order of src and cmp are the *opposite* of the BUFFER_ATOMIC_CMPSWAP opcode.
    
    ..., have been resolved for 'ds_cmpstore_[...]' in the RDNA 3 ISA manual:
    
        In this architecture the order of src and cmp agree with the BUFFER_ATOMIC_CMPSWAP opcode.
    
    ..., and therefore '%2', '%3' now swapped with regards to GCC operand order.
    Most of the affected libgomp OpenACC test cases then PASS their execution test.
    
            gcc/
            * config/gcn/gcn.md (sync_compare_and_swap<mode>_lds_insn)
            [TARGET_RDNA3]: Adjust.

Diff:
---
 gcc/config/gcn/gcn.md | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/gcc/config/gcn/gcn.md b/gcc/config/gcn/gcn.md
index 1f3c692b7a67..925e2cea4895 100644
--- a/gcc/config/gcn/gcn.md
+++ b/gcc/config/gcn/gcn.md
@@ -2074,7 +2074,12 @@
 	   (match_operand:SIDI 3 "register_operand" "  v")]
 	  UNSPECV_ATOMIC))]
   ""
-  "ds_cmpst_rtn_b<bitsize> %0, %1, %2, %3\;s_waitcnt\tlgkmcnt(0)"
+  {
+    if (TARGET_RDNA3)
+      return "ds_cmpstore_rtn_b<bitsize> %0, %1, %3, %2\;s_waitcnt\tlgkmcnt(0)";
+    else
+      return "ds_cmpst_rtn_b<bitsize> %0, %1, %2, %3\;s_waitcnt\tlgkmcnt(0)";
+  }
   [(set_attr "type" "ds")
    (set_attr "length" "12")])