Skip to content

Commit

Permalink
Add Loop parser + examples for armv7m
Browse files Browse the repository at this point in the history
  • Loading branch information
@dop-amin
dop-amin committed Oct 15, 2024
1 parent 6be707f commit e526546
Show file tree
Hide file tree
Showing 2 changed files with 77 additions and 87 deletions.
35 changes: 35 additions & 0 deletions example.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -293,6 +293,39 @@ def __init__(self, var="", arch=AArch64_Neon, target=Target_CortexA55):
def core(self,slothy):
slothy.config.variable_size=True
slothy.optimize_loop("start")

class Armv7mLoopSubs(Example):
def __init__(self, var="", arch=Arch_Armv7M, target=Target_CortexM7):
name = "loop_subs"
infile = name

if var != "":
name += f"_{var}"
infile += f"_{var}"
name += f"_{target_label_dict[target]}"

super().__init__(infile, name, rename=True, arch=arch, target=target)

def core(self,slothy):
slothy.config.variable_size=True
slothy.optimize_loop("start")

class Armv7mLoopCmp(Example):
def __init__(self, var="", arch=Arch_Armv7M, target=Target_CortexM7):
name = "loop_cmp"
infile = name

if var != "":
name += f"_{var}"
infile += f"_{var}"
name += f"_{target_label_dict[target]}"

super().__init__(infile, name, rename=True, arch=arch, target=target)

def core(self,slothy):
slothy.config.variable_size=True
slothy.config.outputs = ["r6"]
slothy.optimize_loop("start")

class CRT(Example):
def __init__(self):
Expand Down Expand Up @@ -2106,6 +2139,8 @@ def main():
# Loop examples
AArch64LoopSubs(),
LoopLe(),
Armv7mLoopSubs(),
Armv7mLoopCmp(),

CRT(),

Expand Down
129 changes: 42 additions & 87 deletions slothy/targets/arm_v7m/arch_v7m.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@
from enum import Enum
from functools import cache

from slothy.helper import SourceLine
from slothy.helper import SourceLine, Loop
from sympy import simplify

llvm_mca_arch = "arm" # TODO
Expand Down Expand Up @@ -126,16 +126,13 @@ def unconditional(lbl):
yield f"b {lbl}"


class Loop:
"""Helper functions for parsing and writing simple loops in armv7m
TODO: Generalize; current implementation too specific about shape of loop"""

def __init__(self, lbl_start="1", lbl_end="2", loop_init="lr"):
self.lbl_start = lbl_start
self.lbl_end = lbl_end
self.loop_init = loop_init

class CmpLoop(Loop):
def __init__(self, lbl="lbl", lbl_start="1", lbl_end="2", loop_init="lr") -> None:
super().__init__(lbl_start=lbl_start, lbl_end=lbl_end, loop_init=loop_init)
self.lbl_regex = r"^\s*(?P<label>\w+)\s*:(?P<remainder>.*)$"
self.end_regex = (r"^\s*cmp(?:\.w)?\s+(?P<cnt>\w+),\s*(?P<reg1>\w+)",
rf"^\s*(cbnz|cbz|bne)(?:\.w)?\s+{lbl}")

def start(self, loop_cnt, indentation=0, fixup=0, unroll=1, jump_if_empty=None):
"""Emit starting instruction(s) and jump label for loop"""
indent = ' ' * indentation
Expand All @@ -147,89 +144,47 @@ def start(self, loop_cnt, indentation=0, fixup=0, unroll=1, jump_if_empty=None):
if jump_if_empty is not None:
yield f"cbz {loop_cnt}, {jump_if_empty}"
yield f"{self.lbl_start}:"

def end(self, other, indentation=0):
"""Emit compare-and-branch at the end of the loop"""
(reg0, reg1, imm) = other
indent = ' ' * indentation
lbl_start = self.lbl_start
if lbl_start.isdigit():
lbl_start += "b"

yield f'{indent}cmp {other["cnt"]}, {other["reg1"]}'
yield f'{indent}bne {lbl_start}'

class SubsLoop(Loop):
def __init__(self, lbl_start="1", lbl_end="2", loop_init="lr") -> None:
super().__init__(lbl_start=lbl_start, lbl_end=lbl_end, loop_init=loop_init)
self.lbl_regex = r"^\s*(?P<label>\w+)\s*:(?P<remainder>.*)$"
self.end_regex = (r"^\s*sub[s]?(?:\.w)?\s+(?P<cnt>\w+),(?:\s*(?P<reg1>\w+),)?\s*(?P<imm>#1)",
rf"^\s*(cbnz|cbz|bne)(?:\.w)?\s+{lbl_start}")

yield f"{indent}subs {reg0}, {reg1}, {imm}" # `subs` sets flags
yield f"{indent}cbnz {reg0}, {lbl_start}"

@staticmethod
def extract(source, lbl):
"""Locate a loop with start label `lbl` in `source`.
We currently only support the following loop forms:
```
loop_lbl:
{code}
sub[s] <cnt>, <cnt>, #1
(cbnz|cbz|bne) <cnt>, loop_lbl
```
"""
assert isinstance(source, list)

pre = []
body = []
post = []
loop_lbl_regexp_txt = r"^\s*(?P<label>\w+)\s*:(?P<remainder>.*)$"
loop_lbl_regexp = re.compile(loop_lbl_regexp_txt)

# TODO: Allow other forms of looping

loop_end_regexp_txt = (r"^\s*sub[s]?\s+(?P<reg0>\w+),\s*(?P<reg1>\w+),\s*(?P<imm>#1)",
rf"^\s*(cbnz|cbz|bne)\s+(?P<reg0>\w+),\s*{lbl}")
loop_end_regexp = [re.compile(txt) for txt in loop_end_regexp_txt]
lines = iter(source)
l = None
keep = False
state = 0 # 0: haven't found loop yet, 1: extracting loop, 2: after loop
while True:
if not keep:
l = next(lines, None)
keep = False
if l is None:
break
l_str = l.text
assert isinstance(l, str) is False
if state == 0:
p = loop_lbl_regexp.match(l_str)
if p is not None and p.group("label") == lbl:
l = l.copy().set_text(p.group("remainder"))
keep = True
state = 1
else:
pre.append(l)
continue
if state == 1:
p = loop_end_regexp[0].match(l_str)
if p is not None:
reg0 = p.group("reg0")
reg1 = p.group("reg1")
imm = p.group("imm")
state = 2
continue
body.append(l)
continue
if state == 2:
p = loop_end_regexp[1].match(l_str)
if p is not None:
state = 3
continue
body.append(l)
continue
if state == 3:
post.append(l)
continue
if state < 3:
raise FatalParsingException(f"Couldn't identify loop {lbl}")
return pre, body, post, lbl, (reg0, reg1, imm)
def start(self, loop_cnt, indentation=0, fixup=0, unroll=1, jump_if_empty=None):
"""Emit starting instruction(s) and jump label for loop"""
indent = ' ' * indentation
if unroll > 1:
assert unroll in [1,2,4,8,16,32]
yield f"{indent}lsr {loop_cnt}, {loop_cnt}, #{int(math.log2(unroll))}"
if fixup != 0:
yield f"{indent}sub {loop_cnt}, {loop_cnt}, #{fixup}"
if jump_if_empty is not None:
yield f"cbz {loop_cnt}, {jump_if_empty}"
yield f"{self.lbl_start}:"

def end(self, other, indentation=0):
"""Emit compare-and-branch at the end of the loop"""
indent = ' ' * indentation
lbl_start = self.lbl_start
if lbl_start.isdigit():
lbl_start += "b"
if other["reg1"] is None:
yield f'{indent}subs {other["cnt"]}, #1'
else:
yield f'{indent}subs {other["cnt"]}, {other["reg1"]}, {other["imm"]}' # `subs` sets flags
yield f'{indent}bne {lbl_start}'

class FatalParsingException(Exception):
"""A fatal error happened during instruction parsing"""
Expand Down

0 comments on commit e526546

Please sign in to comment.