On 31/01/2024 10:36, Thomas Schwinge wrote:
Hi!
OK to push "GCN, RDNA 3: Adjust 'sync_compare_and_swap<mode>_lds_insn'",
see attached?
In pre-RDNA 3 ISA manuals, there are notes for 'DS_CMPST_[...]', like:
Caution, the order of src and cmp are the *opposite* of the
BUFFER_ATOMIC_CMPSWAP opcode.
..., and conversely in the RDNA 3 ISA manual, for 'DS_CMPSTORE_[...]':
In this architecture the order of src and cmp agree with the
BUFFER_ATOMIC_CMPSWAP opcode.
Is my understanding correct, that this isn't something we have to worry
about at the GCC machine description level; that's resolved at the
assembler level?
Right, the IR uses GCC's operand order and has nothing to do with the
assembler syntax; the output template does the mapping.
--- a/gcc/config/gcn/gcn.md
+++ b/gcc/config/gcn/gcn.md
@@ -2095,7 +2095,12 @@
(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, %2,
%3\;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")])
I think you need to swap %2 and %3 in the new format. ds_cmpst matches
GCC operand order, but ds_cmpstore has "cmp" and "src" reversed.
Andrew
