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qemu/target/hexagon/gen_helper_protos.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

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#!/usr/bin/env python3
##
## Copyright(c) 2019-2023 Qualcomm Innovation Center, Inc. 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
import hex_common
##
## Helpers for gen_helper_prototype
##
def_helper_types = {
"N": "s32",
"O": "s32",
"P": "s32",
"M": "s32",
"C": "s32",
"R": "s32",
"V": "ptr",
"Q": "ptr",
}
def_helper_types_pair = {
"R": "s64",
"C": "s64",
"S": "s64",
"G": "s64",
"V": "ptr",
"Q": "ptr",
}
def gen_def_helper_opn(f, tag, regtype, regid, toss, numregs, i):
if hex_common.is_pair(regid):
f.write(f", {def_helper_types_pair[regtype]}")
elif hex_common.is_single(regid):
f.write(f", {def_helper_types[regtype]}")
else:
print("Bad register parse: ", regtype, regid, toss, numregs)
##
## Generate the DEF_HELPER prototype for an instruction
## For A2_add: Rd32=add(Rs32,Rt32)
## We produce:
## DEF_HELPER_3(A2_add, s32, env, s32, s32)
##
def gen_helper_prototype(f, tag, tagregs, tagimms):
regs = tagregs[tag]
imms = tagimms[tag]
numresults = 0
numscalarresults = 0
numscalarreadwrite = 0
for regtype, regid, toss, numregs in regs:
if hex_common.is_written(regid):
numresults += 1
if hex_common.is_scalar_reg(regtype):
numscalarresults += 1
if hex_common.is_readwrite(regid):
if hex_common.is_scalar_reg(regtype):
numscalarreadwrite += 1
if numscalarresults > 1:
## The helper is bogus when there is more than one result
f.write(f"DEF_HELPER_1({tag}, void, env)\n")
else:
## Figure out how many arguments the helper will take
if numscalarresults == 0:
def_helper_size = len(regs) + len(imms) + numscalarreadwrite + 1
if hex_common.need_pkt_has_multi_cof(tag):
def_helper_size += 1
if hex_common.need_pkt_need_commit(tag):
def_helper_size += 1
if hex_common.need_part1(tag):
def_helper_size += 1
if hex_common.need_slot(tag):
def_helper_size += 1
if hex_common.need_PC(tag):
def_helper_size += 1
if hex_common.helper_needs_next_PC(tag):
def_helper_size += 1
if hex_common.need_condexec_reg(tag, regs):
def_helper_size += 1
f.write(f"DEF_HELPER_{def_helper_size}({tag}")
## The return type is void
f.write(", void")
else:
def_helper_size = len(regs) + len(imms) + numscalarreadwrite
if hex_common.need_pkt_has_multi_cof(tag):
def_helper_size += 1
if hex_common.need_pkt_need_commit(tag):
def_helper_size += 1
if hex_common.need_part1(tag):
def_helper_size += 1
if hex_common.need_slot(tag):
def_helper_size += 1
if hex_common.need_PC(tag):
def_helper_size += 1
if hex_common.need_condexec_reg(tag, regs):
def_helper_size += 1
if hex_common.helper_needs_next_PC(tag):
def_helper_size += 1
f.write(f"DEF_HELPER_{def_helper_size}({tag}")
## Generate the qemu DEF_HELPER type for each result
## Iterate over this list twice
## - Emit the scalar result
## - Emit the vector result
i = 0
for regtype, regid, toss, numregs in regs:
if hex_common.is_written(regid):
if not hex_common.is_hvx_reg(regtype):
gen_def_helper_opn(f, tag, regtype, regid, toss, numregs, i)
i += 1
## Put the env between the outputs and inputs
f.write(", env")
i += 1
# Second pass
for regtype, regid, toss, numregs in regs:
if hex_common.is_written(regid):
if hex_common.is_hvx_reg(regtype):
gen_def_helper_opn(f, tag, regtype, regid, toss, numregs, i)
i += 1
## For conditional instructions, we pass in the destination register
if "A_CONDEXEC" in hex_common.attribdict[tag]:
for regtype, regid, toss, numregs in regs:
if hex_common.is_writeonly(regid) and not hex_common.is_hvx_reg(
regtype
):
gen_def_helper_opn(f, tag, regtype, regid, toss, numregs, i)
i += 1
## Generate the qemu type for each input operand (regs and immediates)
for regtype, regid, toss, numregs in regs:
if hex_common.is_read(regid):
if hex_common.is_hvx_reg(regtype) and hex_common.is_readwrite(regid):
continue
gen_def_helper_opn(f, tag, regtype, regid, toss, numregs, i)
i += 1
for immlett, bits, immshift in imms:
f.write(", s32")
## Add the arguments for the instruction pkt_has_multi_cof,
## pkt_needs_commit, PC, next_PC, slot, and part1 (if needed)
if hex_common.need_pkt_has_multi_cof(tag):
f.write(", i32")
if hex_common.need_pkt_need_commit(tag):
f.write(', i32')
if hex_common.need_PC(tag):
f.write(", i32")
if hex_common.helper_needs_next_PC(tag):
f.write(", i32")
if hex_common.need_slot(tag):
f.write(", i32")
if hex_common.need_part1(tag):
f.write(" , i32")
f.write(")\n")
def main():
hex_common.read_semantics_file(sys.argv[1])
hex_common.read_attribs_file(sys.argv[2])
hex_common.read_overrides_file(sys.argv[3])
hex_common.read_overrides_file(sys.argv[4])
## Whether or not idef-parser is enabled is
## determined by the number of arguments to
## this script:
##
## 5 args. -> not enabled,
## 6 args. -> idef-parser enabled.
##
## The 6:th arg. then holds a list of the successfully
## parsed instructions.
is_idef_parser_enabled = len(sys.argv) > 6
if is_idef_parser_enabled:
hex_common.read_idef_parser_enabled_file(sys.argv[5])
hex_common.calculate_attribs()
tagregs = hex_common.get_tagregs()
tagimms = hex_common.get_tagimms()
output_file = sys.argv[-1]
with open(output_file, "w") as f:
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 the diag instructions
if tag == "Y6_diag":
continue
if tag == "Y6_diag0":
continue
if tag == "Y6_diag1":
continue
if hex_common.skip_qemu_helper(tag):
continue
if hex_common.is_idef_parser_enabled(tag):
continue
gen_helper_prototype(f, tag, tagregs, tagimms)
if __name__ == "__main__":
main()
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