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decodetree: Allow grouping of overlapping patterns

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Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This commit is contained in:
Richard Henderson 2019-02-23 11:35:36 -08:00
parent eb6b87fac7
commit 0eff2df4a2
3 changed files with 207 additions and 22 deletions
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58
docs/devel/decodetree.rst
View File

@ -161,3 +161,61 @@ which will, in part, invoke::
and::
trans_addl_i(ctx, &arg_opi, insn)
Pattern Groups
==============
Syntax::
group := '{' ( pat_def | group )+ '}'
A *group* begins with a lone open-brace, with all subsequent lines
indented two spaces, and ending with a lone close-brace. Groups
may be nested, increasing the required indentation of the lines
within the nested group to two spaces per nesting level.
Unlike ungrouped patterns, grouped patterns are allowed to overlap.
Conflicts are resolved by selecting the patterns in order. If all
of the fixedbits for a pattern match, its translate function will
be called. If the translate function returns false, then subsequent
patterns within the group will be matched.
The following example from PA-RISC shows specialization of the *or*
instruction::
{
{
nop 000010 ----- ----- 0000 001001 0 00000
copy 000010 00000 r1:5 0000 001001 0 rt:5
}
or 000010 rt2:5 r1:5 cf:4 001001 0 rt:5
}
When the *cf* field is zero, the instruction has no side effects,
and may be specialized. When the *rt* field is zero, the output
is discarded and so the instruction has no effect. When the *rt2*
field is zero, the operation is ``reg[rt] | 0`` and so encodes
the canonical register copy operation.
The output from the generator might look like::
switch (insn & 0xfc000fe0) {
case 0x08000240:
/* 000010.. ........ ....0010 010..... */
if ((insn & 0x0000f000) == 0x00000000) {
/* 000010.. ........ 00000010 010..... */
if ((insn & 0x0000001f) == 0x00000000) {
/* 000010.. ........ 00000010 01000000 */
extract_decode_Fmt_0(&u.f_decode0, insn);
if (trans_nop(ctx, &u.f_decode0)) return true;
}
if ((insn & 0x03e00000) == 0x00000000) {
/* 00001000 000..... 00000010 010..... */
extract_decode_Fmt_1(&u.f_decode1, insn);
if (trans_copy(ctx, &u.f_decode1)) return true;
}
}
extract_decode_Fmt_2(&u.f_decode2, insn);
if (trans_or(ctx, &u.f_decode2)) return true;
return false;
}

165
scripts/decodetree.py
View File

@ -31,6 +31,7 @@ fields = {}
arguments = {}
formats = {}
patterns = []
allpatterns = []
translate_prefix = 'trans'
translate_scope = 'static '
@ -300,13 +301,7 @@ class General:
self.fields = flds
def __str__(self):
r = self.name
if self.base:
r = r + ' ' + self.base.name
else:
r = r + ' ' + str(self.fields)
r = r + ' ' + str_match_bits(self.fixedbits, self.fixedmask)
return r
return self.name + ' ' + str_match_bits(self.fixedbits, self.fixedmask)
def str1(self, i):
return str_indent(i) + self.__str__()
@ -353,6 +348,47 @@ class Pattern(General):
# end Pattern
class MultiPattern(General):
"""Class representing an overlapping set of instruction patterns"""
def __init__(self, lineno, pats, fixb, fixm, udfm):
self.file = input_file
self.lineno = lineno
self.pats = pats
self.base = None
self.fixedbits = fixb
self.fixedmask = fixm
self.undefmask = udfm
def __str__(self):
r = "{"
for p in self.pats:
r = r + ' ' + str(p)
return r + "}"
def output_decl(self):
for p in self.pats:
p.output_decl()
def output_code(self, i, extracted, outerbits, outermask):
global translate_prefix
ind = str_indent(i)
for p in self.pats:
if outermask != p.fixedmask:
innermask = p.fixedmask & ~outermask
innerbits = p.fixedbits & ~outermask
output(ind, 'if ((insn & ',
'0x{0:08x}) == 0x{1:08x}'.format(innermask, innerbits),
') {\n')
output(ind, ' /* ',
str_match_bits(p.fixedbits, p.fixedmask), ' */\n')
p.output_code(i + 4, extracted, p.fixedbits, p.fixedmask)
output(ind, '}\n')
else:
p.output_code(i, extracted, p.fixedbits, p.fixedmask)
#end MultiPattern
def parse_field(lineno, name, toks):
"""Parse one instruction field from TOKS at LINENO"""
global fields
@ -505,6 +541,7 @@ def parse_generic(lineno, is_format, name, toks):
global arguments
global formats
global patterns
global allpatterns
global re_ident
global insnwidth
global insnmask
@ -649,6 +686,7 @@ def parse_generic(lineno, is_format, name, toks):
pat = Pattern(name, lineno, fmt, fixedbits, fixedmask,
undefmask, fieldmask, flds)
patterns.append(pat)
allpatterns.append(pat)
# Validate the masks that we have assembled.
if fieldmask & fixedmask:
@ -667,17 +705,66 @@ def parse_generic(lineno, is_format, name, toks):
.format(allbits ^ insnmask))
# end parse_general
def build_multi_pattern(lineno, pats):
"""Validate the Patterns going into a MultiPattern."""
global patterns
global insnmask
if len(pats) < 2:
error(lineno, 'less than two patterns within braces')
fixedmask = insnmask
undefmask = insnmask
# Collect fixed/undefmask for all of the children.
# Move the defining lineno back to that of the first child.
for p in pats:
fixedmask &= p.fixedmask
undefmask &= p.undefmask
if p.lineno < lineno:
lineno = p.lineno
repeat = True
while repeat:
if fixedmask == 0:
error(lineno, 'no overlap in patterns within braces')
fixedbits = None
for p in pats:
thisbits = p.fixedbits & fixedmask
if fixedbits is None:
fixedbits = thisbits
elif fixedbits != thisbits:
fixedmask &= ~(fixedbits ^ thisbits)
break
else:
repeat = False
mp = MultiPattern(lineno, pats, fixedbits, fixedmask, undefmask)
patterns.append(mp)
# end build_multi_pattern
def parse_file(f):
"""Parse all of the patterns within a file"""
global patterns
# Read all of the lines of the file. Concatenate lines
# ending in backslash; discard empty lines and comments.
toks = []
lineno = 0
nesting = 0
saved_pats = []
for line in f:
lineno += 1
# Expand and strip spaces, to find indent.
line = line.rstrip()
line = line.expandtabs()
len1 = len(line)
line = line.lstrip()
len2 = len(line)
# Discard comments
end = line.find('#')
if end >= 0:
@ -687,10 +774,18 @@ def parse_file(f):
if len(toks) != 0:
# Next line after continuation
toks.extend(t)
elif len(t) == 0:
# Empty line
continue
else:
# Allow completely blank lines.
if len1 == 0:
continue
indent = len1 - len2
# Empty line due to comment.
if len(t) == 0:
# Indentation must be correct, even for comment lines.
if indent != nesting:
error(lineno, 'indentation ', indent, ' != ', nesting)
continue
start_lineno = lineno
toks = t
# Continuation?
@ -698,21 +793,47 @@ def parse_file(f):
toks.pop()
continue
if len(toks) < 2:
error(lineno, 'short line')
name = toks[0]
del toks[0]
# End nesting?
if name == '}':
if nesting == 0:
error(start_lineno, 'mismatched close brace')
if len(toks) != 0:
error(start_lineno, 'extra tokens after close brace')
nesting -= 2
if indent != nesting:
error(start_lineno, 'indentation ', indent, ' != ', nesting)
pats = patterns
patterns = saved_pats.pop()
build_multi_pattern(lineno, pats)
toks = []
continue
# Everything else should have current indentation.
if indent != nesting:
error(start_lineno, 'indentation ', indent, ' != ', nesting)
# Start nesting?
if name == '{':
if len(toks) != 0:
error(start_lineno, 'extra tokens after open brace')
saved_pats.append(patterns)
patterns = []
nesting += 2
toks = []
continue
# Determine the type of object needing to be parsed.
if name[0] == '%':
parse_field(lineno, name[1:], toks)
parse_field(start_lineno, name[1:], toks)
elif name[0] == '&':
parse_arguments(lineno, name[1:], toks)
parse_arguments(start_lineno, name[1:], toks)
elif name[0] == '@':
parse_generic(lineno, True, name[1:], toks)
parse_generic(start_lineno, True, name[1:], toks)
else:
parse_generic(lineno, False, name, toks)
parse_generic(start_lineno, False, name, toks)
toks = []
# end parse_file
@ -789,11 +910,10 @@ def build_tree(pats, outerbits, outermask):
innermask &= i.fixedmask
if innermask == 0:
pnames = []
text = 'overlapping patterns:'
for p in pats:
pnames.append(p.name + ':' + p.file + ':' + str(p.lineno))
error_with_file(pats[0].file, pats[0].lineno,
'overlapping patterns:', pnames)
text += '\n' + p.file + ':' + str(p.lineno) + ': ' + str(p)
error_with_file(pats[0].file, pats[0].lineno, text)
fullmask = outermask | innermask
@ -846,6 +966,7 @@ def main():
global arguments
global formats
global patterns
global allpatterns
global translate_scope
global translate_prefix
global output_fd
@ -907,7 +1028,7 @@ def main():
# Make sure that the argument sets are the same, and declare the
# function only once.
out_pats = {}
for i in patterns:
for i in allpatterns:
if i.name in out_pats:
p = out_pats[i.name]
if i.base.base != p.base.base:

6
tests/decode/err_pattern_group_overlap1.decode Normal file
View File

@ -0,0 +1,6 @@
one 00000000000000000000000000000000
{
two 0000000000000000000000000000000 s:1
three 000000000000000000000000000000 s:1 0
}