On 28/11/2022 07:40, Tobias Burnus wrote:
It turned out that cprop cleverly propagated the unspec_volatile
to the preceding (pseudo)register, permitting to remove the
'set (s0) (pseudoregister)' at -O2. Unfortunately, it does
matter whether the assignment is done to 's2' (previously: pseudoregister)
or to s1. – Just having a hard register is not enough ...
Solution: Use USE (alias gen_rtx_USE) instead.
Additionally, I removed the s0 modification (that should lead to the
unchanged result)
by adding 'gcn_operand_part (DImode, reg, 1)' and then working with
SImode. Result:
if (__builtin_gcn_first_call_this_thread_p())
x = 42;
becomes now (with -O2) the following; the builtin code is up to to (and
including)
'.L2', the rest is the 'if' and 'x=42':
s_lshr_b32 s2, s1, 16
s_cmpk_lg_u32 s2, 12345
s_mov_b32 s12, scc
s_mov_b32 vcc_lo, scc
s_mov_b32 vcc_hi, 0
s_cbranch_vccz .L2
s_and_b32 s2, s1, 65535 (= 0xFFFF)
s_or_b32 s1, s2, 809041920 (= 0x30390000 = (12345 << 16))
.L2:
s_getpc_b64 s[2:3]
s_add_u32 s2, s2, x@rel32@lo+4
s_addc_u32 s3, s3, x@rel32@hi+4
s_mov_b32 vcc_lo, s12
s_mov_b32 vcc_hi, 0
s_cbranch_vccz .L3
s_mov_b32 s12, 42
v_writelane_b32 v0, s12, 0
s_mov_b64 exec, 1
global_store_dword v1, v0, s[2:3]
.L3:
OK for mainline?
OK.
Andrew
