qemu-e2k/target/hexagon/gen_idef_parser_funcs.py
Taylor Simpson d54c56156f Hexagon (target/hexagon) Short-circuit packet register writes
In certain cases, we can avoid the overhead of writing to hex_new_value
and write directly to hex_gpr.  We add need_commit field to DisasContext
indicating if the end-of-packet commit is needed.  If it is not needed,
get_result_gpr() and get_result_gpr_pair() can return hex_gpr.

We pass the ctx->need_commit to helpers when needed.

Finally, we can early-exit from gen_reg_writes during packet commit.

There are a few instructions whose semantics write to the result before
reading all the inputs.  Therefore, the idef-parser generated code is
incompatible with short-circuit.  We tell idef-parser to skip them.

For debugging purposes, we add a cpu property to turn off short-circuit.
When the short-circuit property is false, we skip the analysis and force
the end-of-packet commit.

Here's a simple example of the TCG generated for
0x004000b4:  0x7800c020 {       R0 = #0x1 }

BEFORE:
 ---- 004000b4
 movi_i32 new_r0,$0x1
 mov_i32 r0,new_r0

AFTER:
 ---- 004000b4
 movi_i32 r0,$0x1

This patch reintroduces a use of check_for_attrib, so we remove the
G_GNUC_UNUSED added earlier in this series.

Signed-off-by: Taylor Simpson <tsimpson@quicinc.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Brian Cain <bcain@quicinc.com>
Message-Id: <20230427230012.3800327-12-tsimpson@quicinc.com>
2023-05-18 12:40:52 -07:00

157 lines
5.1 KiB
Python

#!/usr/bin/env python3
##
## Copyright(c) 2019-2023 rev.ng Labs Srl. All Rights Reserved.
##
## This program is free software; you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation; either version 2 of the License, or
## (at your option) any later version.
##
## This program is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with this program; if not, see <http://www.gnu.org/licenses/>.
##
import sys
import re
import string
from io import StringIO
import hex_common
##
## Generate code to be fed to the idef_parser
##
## Consider A2_add:
##
## Rd32=add(Rs32,Rt32), { RdV=RsV+RtV;}
##
## We produce:
##
## A2_add(RdV, in RsV, in RtV) {
## { RdV=RsV+RtV;}
## }
##
## A2_add represents the instruction tag. Then we have a list of TCGv
## that the code generated by the parser can expect in input. Some of
## them are inputs ("in" prefix), while some others are outputs.
##
def main():
hex_common.read_semantics_file(sys.argv[1])
hex_common.read_attribs_file(sys.argv[2])
hex_common.calculate_attribs()
tagregs = hex_common.get_tagregs()
tagimms = hex_common.get_tagimms()
with open(sys.argv[3], "w") as f:
f.write('#include "macros.inc"\n\n')
for tag in hex_common.tags:
## Skip the priv instructions
if "A_PRIV" in hex_common.attribdict[tag]:
continue
## Skip the guest instructions
if "A_GUEST" in hex_common.attribdict[tag]:
continue
## Skip instructions that saturate in a ternary expression
if tag in {"S2_asr_r_r_sat", "S2_asl_r_r_sat"}:
continue
## Skip instructions using switch
if tag in {"S4_vrcrotate_acc", "S4_vrcrotate"}:
continue
## Skip trap instructions
if tag in {"J2_trap0", "J2_trap1"}:
continue
## Skip 128-bit instructions
if tag in {"A7_croundd_ri", "A7_croundd_rr"}:
continue
if tag in {
"M7_wcmpyrw",
"M7_wcmpyrwc",
"M7_wcmpyiw",
"M7_wcmpyiwc",
"M7_wcmpyrw_rnd",
"M7_wcmpyrwc_rnd",
"M7_wcmpyiw_rnd",
"M7_wcmpyiwc_rnd",
}:
continue
## Skip interleave/deinterleave instructions
if tag in {"S2_interleave", "S2_deinterleave"}:
continue
## Skip instructions using bit reverse
if tag in {
"S2_brev",
"S2_brevp",
"S2_ct0",
"S2_ct1",
"S2_ct0p",
"S2_ct1p",
"A4_tlbmatch",
}:
continue
## Skip other unsupported instructions
if tag == "S2_cabacdecbin" or tag == "A5_ACS":
continue
if tag.startswith("Y"):
continue
if tag.startswith("V6_"):
continue
if tag.startswith("F"):
continue
if tag.endswith("_locked"):
continue
if "A_COF" in hex_common.attribdict[tag]:
continue
if ( tag.startswith('R6_release_') ):
continue
## Skip instructions that are incompatible with short-circuit
## packet register writes
if ( tag == 'S2_insert' or
tag == 'S2_insert_rp' or
tag == 'S2_asr_r_svw_trun' or
tag == 'A2_swiz' ):
continue
regs = tagregs[tag]
imms = tagimms[tag]
arguments = []
for regtype, regid, toss, numregs in regs:
prefix = "in " if hex_common.is_read(regid) else ""
is_pair = hex_common.is_pair(regid)
is_single_old = hex_common.is_single(regid) and hex_common.is_old_val(
regtype, regid, tag
)
is_single_new = hex_common.is_single(regid) and hex_common.is_new_val(
regtype, regid, tag
)
if is_pair or is_single_old:
arguments.append(f"{prefix}{regtype}{regid}V")
elif is_single_new:
arguments.append(f"{prefix}{regtype}{regid}N")
else:
print("Bad register parse: ", regtype, regid, toss, numregs)
for immlett, bits, immshift in imms:
arguments.append(hex_common.imm_name(immlett))
f.write(f"{tag}({', '.join(arguments)}) {{\n")
f.write(" ")
if hex_common.need_ea(tag):
f.write("size4u_t EA; ")
f.write(f"{hex_common.semdict[tag]}\n")
f.write("}\n\n")
if __name__ == "__main__":
main()