From 17560e9349ff1fcce814184b37993f92378cf0c4 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Wed, 30 Jan 2019 18:01:29 -0800 Subject: [PATCH] decodetree: Initial support for variable-length ISAs Assuming that the ISA clearly describes how to determine the length of the instruction, and the ISA has a reasonable maximum instruction length, the input to the decoder can be right-justified in an appropriate insn word. This is not 100% convenient, as out-of-line %fields are numbered relative to the maximum instruction length, but this appears to still be usable. Signed-off-by: Richard Henderson --- scripts/decodetree.py | 49 ++++++++++++++++++++++++++++++++----------- 1 file changed, 37 insertions(+), 12 deletions(-) diff --git a/scripts/decodetree.py b/scripts/decodetree.py index aa790b596a..555a46522b 100755 --- a/scripts/decodetree.py +++ b/scripts/decodetree.py @@ -27,6 +27,7 @@ import getopt insnwidth = 32 insnmask = 0xffffffff +variablewidth = False fields = {} arguments = {} formats = {} @@ -289,7 +290,7 @@ class Arguments: class General: """Common code between instruction formats and instruction patterns""" - def __init__(self, name, lineno, base, fixb, fixm, udfm, fldm, flds): + def __init__(self, name, lineno, base, fixb, fixm, udfm, fldm, flds, w): self.name = name self.file = input_file self.lineno = lineno @@ -299,6 +300,7 @@ class General: self.undefmask = udfm self.fieldmask = fldm self.fields = flds + self.width = w def __str__(self): return self.name + ' ' + str_match_bits(self.fixedbits, self.fixedmask) @@ -352,7 +354,7 @@ class Pattern(General): class MultiPattern(General): """Class representing an overlapping set of instruction patterns""" - def __init__(self, lineno, pats, fixb, fixm, udfm): + def __init__(self, lineno, pats, fixb, fixm, udfm, w): self.file = input_file self.lineno = lineno self.pats = pats @@ -360,6 +362,7 @@ class MultiPattern(General): self.fixedbits = fixb self.fixedmask = fixm self.undefmask = udfm + self.width = w def __str__(self): r = "{" @@ -502,7 +505,7 @@ def infer_argument_set(flds): return arg -def infer_format(arg, fieldmask, flds): +def infer_format(arg, fieldmask, flds, width): global arguments global formats global decode_function @@ -521,6 +524,8 @@ def infer_format(arg, fieldmask, flds): continue if fieldmask != fmt.fieldmask: continue + if width != fmt.width: + continue if not eq_fields_for_fmts(flds, fmt.fields): continue return (fmt, const_flds) @@ -529,7 +534,7 @@ def infer_format(arg, fieldmask, flds): if not arg: arg = infer_argument_set(flds) - fmt = Format(name, 0, arg, 0, 0, 0, fieldmask, var_flds) + fmt = Format(name, 0, arg, 0, 0, 0, fieldmask, var_flds, width) formats[name] = fmt return (fmt, const_flds) @@ -546,6 +551,7 @@ def parse_generic(lineno, is_format, name, toks): global re_ident global insnwidth global insnmask + global variablewidth fixedmask = 0 fixedbits = 0 @@ -633,8 +639,15 @@ def parse_generic(lineno, is_format, name, toks): error(lineno, 'invalid token "{0}"'.format(t)) width += shift + if variablewidth and width < insnwidth and width % 8 == 0: + shift = insnwidth - width + fixedbits <<= shift + fixedmask <<= shift + undefmask <<= shift + undefmask |= (1 << shift) - 1 + # We should have filled in all of the bits of the instruction. - if not (is_format and width == 0) and width != insnwidth: + elif not (is_format and width == 0) and width != insnwidth: error(lineno, 'definition has {0} bits'.format(width)) # Do not check for fields overlaping fields; one valid usage @@ -660,7 +673,7 @@ def parse_generic(lineno, is_format, name, toks): if name in formats: error(lineno, 'duplicate format name', name) fmt = Format(name, lineno, arg, fixedbits, fixedmask, - undefmask, fieldmask, flds) + undefmask, fieldmask, flds, width) formats[name] = fmt else: # Patterns can reference a format ... @@ -670,12 +683,14 @@ def parse_generic(lineno, is_format, name, toks): error(lineno, 'pattern specifies both format and argument set') if fixedmask & fmt.fixedmask: error(lineno, 'pattern fixed bits overlap format fixed bits') + if width != fmt.width: + error(lineno, 'pattern uses format of different width') fieldmask |= fmt.fieldmask fixedbits |= fmt.fixedbits fixedmask |= fmt.fixedmask undefmask |= fmt.undefmask else: - (fmt, flds) = infer_format(arg, fieldmask, flds) + (fmt, flds) = infer_format(arg, fieldmask, flds, width) arg = fmt.base for f in flds.keys(): if f not in arg.fields: @@ -687,7 +702,7 @@ def parse_generic(lineno, is_format, name, toks): if f not in flds.keys() and f not in fmt.fields.keys(): error(lineno, 'field {0} not initialized'.format(f)) pat = Pattern(name, lineno, fmt, fixedbits, fixedmask, - undefmask, fieldmask, flds) + undefmask, fieldmask, flds, width) patterns.append(pat) allpatterns.append(pat) @@ -727,6 +742,13 @@ def build_multi_pattern(lineno, pats): if p.lineno < lineno: lineno = p.lineno + width = None + for p in pats: + if width is None: + width = p.width + elif width != p.width: + error(lineno, 'width mismatch in patterns within braces') + repeat = True while repeat: if fixedmask == 0: @@ -742,7 +764,7 @@ def build_multi_pattern(lineno, pats): else: repeat = False - mp = MultiPattern(lineno, pats, fixedbits, fixedmask, undefmask) + mp = MultiPattern(lineno, pats, fixedbits, fixedmask, undefmask, width) patterns.append(mp) # end build_multi_pattern @@ -979,13 +1001,14 @@ def main(): global insntype global insnmask global decode_function + global variablewidth decode_scope = 'static ' long_opts = ['decode=', 'translate=', 'output=', 'insnwidth=', - 'static-decode='] + 'static-decode=', 'varinsnwidth='] try: - (opts, args) = getopt.getopt(sys.argv[1:], 'o:w:', long_opts) + (opts, args) = getopt.getopt(sys.argv[1:], 'o:vw:', long_opts) except getopt.GetoptError as err: error(0, err) for o, a in opts: @@ -999,7 +1022,9 @@ def main(): elif o == '--translate': translate_prefix = a translate_scope = '' - elif o in ('-w', '--insnwidth'): + elif o in ('-w', '--insnwidth', '--varinsnwidth'): + if o == '--varinsnwidth': + variablewidth = True insnwidth = int(a) if insnwidth == 16: insntype = 'uint16_t'