scripts/coccinelle/tcg_gen_extract.cocci

   1 // optimize TCG using extract op
   2 //
   3 // Copyright: (C) 2017 Philippe Mathieu-Daudé. GPLv2+.
   4 // Confidence: High
   5 // Options: --macro-file scripts/cocci-macro-file.h
   6 //
   7 // Nikunj A Dadhania optimization:
   8 // http://lists.nongnu.org/archive/html/qemu-devel/2017-02/msg05211.html
   9 // Aurelien Jarno optimization:
  10 // http://lists.nongnu.org/archive/html/qemu-devel/2017-05/msg01466.html
  11 //
  12 // This script can be run either using spatch locally or via a docker image:
  13 //
  14 // $ spatch \
  15 //     --macro-file scripts/cocci-macro-file.h \
  16 //     --sp-file scripts/coccinelle/tcg_gen_extract.cocci \
  17 //     --keep-comments --in-place \
  18 //     --use-gitgrep --dir target
  19 //
  20 // $ docker run --rm -v $PWD:$PWD -w $PWD philmd/coccinelle \
  21 //     --macro-file scripts/cocci-macro-file.h \
  22 //     --sp-file scripts/coccinelle/tcg_gen_extract.cocci \
  23 //     --keep-comments --in-place \
  24 //     --use-gitgrep --dir target
  25
  26 @initialize:python@
  27 @@
  28 import sys
  29 fd = sys.stderr
  30 def debug(msg="", trailer="\n"):
  31     fd.write("[DBG] " + msg + trailer)
  32 def low_bits_count(value):
  33     bits_count = 0
  34     while (value & (1 << bits_count)):
  35         bits_count += 1
  36     return bits_count
  37 def Mn(order): # Mersenne number
  38     return (1 << order) - 1
  39
  40 @match@
  41 identifier ret;
  42 metavariable arg;
  43 constant ofs, msk;
  44 position shr_p, and_p;
  45 @@
  46 (
  47     tcg_gen_shri_i32@shr_p
  48 |
  49     tcg_gen_shri_i64@shr_p
  50 |
  51     tcg_gen_shri_tl@shr_p
  52 )(ret, arg, ofs);
  53 ...  WHEN != ret
  54 (
  55     tcg_gen_andi_i32@and_p
  56 |
  57     tcg_gen_andi_i64@and_p
  58 |
  59     tcg_gen_andi_tl@and_p
  60 )(ret, ret, msk);
  61
  62 @script:python verify_len depends on match@
  63 ret_s << match.ret;
  64 msk_s << match.msk;
  65 shr_p << match.shr_p;
  66 extract_len;
  67 @@
  68 is_optimizable = False
  69 debug("candidate at %s:%s" % (shr_p[0].file, shr_p[0].line))
  70 try: # only eval integer, no #define like 'SR_M' (cpp did this, else some headers are missing).
  71     msk_v = long(msk_s.strip("UL"), 0)
  72     msk_b = low_bits_count(msk_v)
  73     if msk_b == 0:
  74         debug("  value: 0x%x low_bits: %d" % (msk_v, msk_b))
  75     else:
  76         debug("  value: 0x%x low_bits: %d [Mersenne number: 0x%x]" % (msk_v, msk_b, Mn(msk_b)))
  77         is_optimizable = Mn(msk_b) == msk_v # check low_bits
  78         coccinelle.extract_len = "%d" % msk_b
  79     debug("  candidate %s optimizable" % ("IS" if is_optimizable else "is NOT"))
  80 except:
  81     debug("  ERROR (check included headers?)")
  82 cocci.include_match(is_optimizable)
  83 debug()
  84
  85 @replacement depends on verify_len@
  86 identifier match.ret;
  87 metavariable match.arg;
  88 constant match.ofs, match.msk;
  89 position match.shr_p, match.and_p;
  90 identifier verify_len.extract_len;
  91 @@
  92 (
  93 -tcg_gen_shri_i32@shr_p(ret, arg, ofs);
  94 +tcg_gen_extract_i32(ret, arg, ofs, extract_len);
  95 ...  WHEN != ret
  96 -tcg_gen_andi_i32@and_p(ret, ret, msk);
  97 |
  98 -tcg_gen_shri_i64@shr_p(ret, arg, ofs);
  99 +tcg_gen_extract_i64(ret, arg, ofs, extract_len);
 100 ...  WHEN != ret
 101 -tcg_gen_andi_i64@and_p(ret, ret, msk);
 102 |
 103 -tcg_gen_shri_tl@shr_p(ret, arg, ofs);
 104 +tcg_gen_extract_tl(ret, arg, ofs, extract_len);
 105 ...  WHEN != ret
 106 -tcg_gen_andi_tl@and_p(ret, ret, msk);
 107 )