# cur stands for the insn kind that we read and processed in the
# previous iteration of the loop, and prev is the one before it. the
# one we're processing in the current iteration will be stored in
-# next until we make it cur at the very end of the loop.
+# nexti until we make it cur at the very end of the loop.
prev = cur = 0
for line in sys.stdin:
operands = match['operands']
if opcode in copcond:
- next = copcond[opcode](opcode,
+ nexti = copcond[opcode](opcode,
[mapop(op) for op in operands.split(',')])
else:
- next = 0
+ nexti = 0
comment = None
if cur is 0:
- if next is 0:
+ if nexti is 0:
True # Uncompressed mode for good.
- elif next is 1:
+ elif nexti is 1:
# If cur was not a single uncompressed mode insn,
# tentatively encode a 10-bit nop to enter compressed
# mode, and then 16-bit. It takes as much space as
print('\t\th.nop\t\t; tentatively switch to compressed mode')
count[4] += 1
comment = 'tentatively compressed to 16-bit'
- elif next is 2:
- # We can use compressed encoding for next after an
+ elif nexti is 2:
+ # We can use compressed encoding for nexti after an
# uncompressed insn only if it's the single-insn
# uncompressed mode slot. For anything else, we're better
- # off using uncompressed encoding for next, since it makes
+ # off using uncompressed encoding for nexti, since it makes
# no sense to spend a 10-bit nop to switch to compressed
# mode for a 16+16-bit insn. If subsequent insns would
# benefit from compressed encoding, we can switch then.
if prev is not 1:
- next = 0
+ nexti = 0
comment = 'not worth a nop for 16+16-bit'
- elif next is 3:
+ elif nexti is 3:
# If prev was 16-bit compressed, cur would be in the
- # single-insn uncompressed slot, so next could be encoded
+ # single-insn uncompressed slot, so nexti could be encoded
# as 16-bit, enabling another 1-insn uncompressed slot
- # after next that a 10-bit insn wouldn't, so make it so.
+ # after nexti that a 10-bit insn wouldn't, so make it so.
if prev is 1:
- next = 1
+ nexti = 1
comment = '16-bit, could be 10-bit'
elif cur is 1:
# After a 16-bit insn, anything goes. If it remains in 16-bit
- # mode, we can have 1 or 2 as next; if it returns to 32-bit
+ # mode, we can have 1 or 2 as nexti; if it returns to 32-bit
# mode, we can have 0 or 3. Using 1 instead of 3 makes room
# for a subsequent single-insn compressed mode, so prefer
# that.
- if next is 3:
- next = 1
+ if nexti is 3:
+ nexti = 1
comment = '16-bit, could be 10-bit'
elif cur is 2:
# After a 16+16-bit insn, we can't switch directly to 32-bit
# mode. However, cur could have been encoded as 32-bit, since
# any 16+16-bit insn can. Indeed, we may have an arbitrary
- # long sequence of 16+16-bit insns before next, and if next
+ # long sequence of 16+16-bit insns before nexti, and if nexti
# can only be encoded in 32-bit mode, we can "resolve" all
# previous adjacent 16+16-bit insns to the corresponding
# 32-bit insns in the encoding, and "adjust" the 16-bit or
# 10-bit insn that enabled the potential 16+16-bit encoding to
# switch to 32-bit mode then instead.
- if next is 0:
+ if nexti is 0:
prev = cur = 0
comment = '32-bit, like tentative 16+16-bit insns above'
elif cur is 3:
# After a 10-bit insn, another insn that could be encoded as
# 10-bit might as well be encoded as 16-bit, to make room for
# a single-insn uncompressed insn afterwards.
- if next is 3:
- next = 1
+ if nexti is 3:
+ nexti = 1
comment = '16-bit, could be 10-bit'
else:
raise "unknown mode for previous insn"
- count[next] += 1
+ count[nexti] += 1
if comment is None:
- comment = comments[next]
+ comment = comments[nexti]
else:
comment = '\t; ' + comment
print(line + comment)
prev = cur
- cur = next
+ cur = nexti
transition_bytes = 2 * count[4]
compressed_bytes = 2 * (count[1] + count[3])
+++ /dev/null
-#! /bin/env python3
-
-# Feed this script the output of objdump -M raw --no-show-raw-insn ppc-prog
-
-# It will look for insns that can be represented in compressed mode,
-# according to the encoding rules in the copcond dictionary below.
-# It's just a skeleton for testing of the logic,
-# the encoding rules are yet to be filled in.
-
-# Nothing is assumed as to the actual bit-encoding of the insns, this
-# is just to experiment with insn selection and get a quick feedback
-# loop for the encoding options in compressed mode.
-
-# In this script, the computations of encoding modes and transitions
-# are tuned for the simpler model that uses 1-byte nops for
-# transitions in and out of compressed mode, placing compressed-mode
-# insns at odd addresses. At (visible) entry points, mode is forced
-# to return to uncompressed mode.
-
-# The entire code stream is printed, without any attempt to modify the
-# addresses that go along with or in them; we only insert markers for
-# the transition points, and for the compressed instructions.
-
-# The really useful information is printed at the end: a summary of
-# transition and compressed-insn counts, and the achieved compression
-# rate.
-
-import sys
-import re
-
-insn = re.compile('\s+(?P<addr>[0-9a-f]+):\s+(?P<opcode>[^ ]+) *(?P<operands>.*)')
-
-opkind = re.compile('(?P<reg>(?P<regkind>[cf]?r)(?P<regnum>[0-9]+))|(?P<immediate>-?[0-9]+)|(?P<branch>[0-9a-f]+)(?: <.*>)?|(?P<offset>-?[0-9]+)\((?P<basereg>r[0-9]+)\)')
-
-def mapop(op):
- match = opkind.fullmatch(op)
-
- if match is None:
- op = ('other', op)
- elif match['reg'] is not None:
- op = (match['regkind'], int(match['regnum']))
- elif match['immediate'] is not None:
- op = ('imm', int (op).bit_length ())
- elif match['branch'] is not None:
- op = ('pcoff', (int (match['branch'], 16)
- - int (addr, 16)).bit_length ())
- elif match['offset'] is not None:
- op = ('ofst', mapop(match['offset']), mapop(match['basereg']))
- else:
- raise "unrecognized operand kind"
-
- return op
-
-def opclass(mop):
- return mop[0]
-def regno(mop):
- if mop[0] in { 'r', 'fr', 'cr' }:
- return mop[1]
- else:
- raise "operand is not a register"
-
-def immbits(mop):
- if mop[0] is 'imm':
- return mop[1]
- else:
- raise "operand is not an immediate"
-
-# Following are predicates to be used in copcond, to tell the mode in
-# which opcode with ops as operands is to be represented
-
-# Any occurrence of the opcode can be compressed.
-def anyops(opcode, ops):
- return 1
-
-# Compress iff first and second operands are the same.
-def same01(opcode, ops):
- if ops[0] == ops[1]:
- return 1
- else:
- return 0
-
-# Registers representable in a made-up 3-bit mapping.
-cregs2 = { 1, 2, 3, 4, 5, 6, 7, 31 }
-
-# Return true iff mop is a regular register present in cregs2
-def bin2regs3(mop):
- return opclass(mop) is 'r' and regno(mop) in cregs2
-
-# Return true iff mop is an immediate of at most 8 bits.
-def imm8(mop):
- return opclass(mop) is 'imm' and immbits(mop) <= 8
-
-# Compress binary opcodes iff the first two operands (output and first
-# input operand) are registers representable in 3 bits in compressed
-# mode, and the immediate operand can be represented in 8 bits.
-def bin2regs3imm8(opcode, ops):
- if bin2regs3(ops[0]) and bin2regs3(ops[1]) and imm8(ops[2]):
- return 1
- else:
- return 0
-
-# Map opcodes that might be compressed to a function that returns the
-# mode (index into mode_list below) in which the insn is to be
-# represented. Those not mentioned in copcond are assumed
-# Uncomopressed.
-copcond = {
- # Pretending anything goes, just for demonstration purposes.
- 'mr': anyops,
- 'ld': anyops,
- 'std': anyops,
- # Output and first input operand must coincide for these.
- 'add': same01,
- 'sub': same01,
- # Limiting register and operand range:
- 'addi': bin2regs3imm8
- # Anything else is uncompressed.
-}
-
-enter_compressed = 0
-leave_compressed = 0
-count_compressed = 0
-count_uncompressed = 0
-current_mode = 0
-mode_list = ['Uncompressed', 'Compressed'] # for documentation purposes only
-
-for line in sys.stdin:
- if line[-1] is '\n':
- line = line[:-1]
-
- match = insn.fullmatch(line)
- if match is None:
- print(line)
- # Switch to uncompressed mode at function boundaries
- if current_mode is not 0:
- print('<leave compressed mode>')
- current_mode = 0
- leave_compressed += 1
- continue
-
- addr = match['addr']
- opcode = match['opcode']
- operands = match['operands']
-
- if opcode in copcond:
- this_mode = copcond[opcode](opcode,
- [mapop(op) for op in operands.split(',')])
- else:
- this_mode = 0
-
- if this_mode is 1:
- if current_mode is not 1:
- print('\t\tcin.nop')
- current_mode = 1
- enter_compressed += 1
- print(line + ' (c)')
- count_compressed += 1
- else:
- if current_mode is not 0:
- print('\t\tcout.nop')
- current_mode = 0
- leave_compressed += 1
- print(line)
- count_uncompressed += 1
-
-transition_bytes = 1 * enter_compressed + 1 * leave_compressed
-compressed_bytes = 2 * count_compressed
-uncompressed_bytes = 4 * count_uncompressed
-total_bytes = transition_bytes + compressed_bytes + uncompressed_bytes
-original_bytes = 2 * compressed_bytes + uncompressed_bytes
-
-print()
-print('Summary')
-print('Compressed instructions: %i' % count_compressed)
-print('Uncompressed instructions: %i' % count_uncompressed)
-print('Transitions into compressed mode: %i' % enter_compressed)
-print('Transitions out of compressed mode: %i' % leave_compressed)
-print('Compressed size estimate: %i' % total_bytes)
-print('Original size: %i' % original_bytes)
-print('Compressed/original ratio: %f' % (total_bytes / original_bytes))
projects / libreriscv.git / commitdiff