[Qemu-devel] [RFC PATCH v4 0/6] optimize various tcg_gen() functions using extract op

[Philippe Mathieu-Daudé]

* Changes from v3

Tried to fix wrong previous attempt...
After getting some nice/fast pieces of advice from Coccinelle folks, I tried to
improved the script (not much inline documentation yet although).
- correctly check if this optimizable?
- document as Mersenne number instead of prime (Eric Blake)
- try to write Python code instead of BASIC (Markus Elfring advices)
- try to reduce regex usage
- try to match shri(); unrelated(); andi(); pattern to optimize, I was surprised
  to see the alpha diff Coccinelle found.

This is surely not the last version of this patchset, but I think now the
generated patches are correct and I prefer reviewers to look at them fixed
instead of wrong one in the ML.
Still lot of work to do in the cocci script, now it seems to hang trying to
parse "target/arm/translate.c".

* [v3] (v2 was a resend of the cocci script):

In my first attempt I misunderstood tcg_gen_extract() intrinsics, and Richard
Henderson pointed that out.
In this patchset the cocci script is corrected and clarified, it also print how
arguments are checked while running.
Also:
- incorrect patches have been removed. (Richard Henderson, Nikunj A Dadhania)
- Coccinelle script licensed GPLv2+ (Eric Blake)
- comment in each commit about how to apply the patch (Eric Blake)
- added Acked-by for m68k (Laurent Vivier)
- Cc: Coccinelle developers.

[v1]

While reviewing a commit from Aurelien Jarno where he optimized a TCG generator
for SH-4 [1] I found the same optimization done on PPC by Nikunj A Dadhania few
months ago [2].
After asking on the ML about a cocci script [3] I thought it would be easier to
learn about Coccinelle.

citing Aurelien Jarno:
    This doesn't change the generated code on x86, but optimizes it on most
    RISC architectures and makes the code simpler to read.

I actually applied the script using the following command:

$ docker run -v `pwd`:`pwd` -w `pwd` petersenna/coccinelle \
    --sp-file scripts/coccinelle/tcg_gen_extract.cocci \
    --macro-file scripts/cocci-macro-file.h \
    --dir target \
    --in-place

Please review again! thanks.

[1] http://lists.nongnu.org/archive/html/qemu-devel/2017-05/msg01466.html
[2] http://lists.nongnu.org/archive/html/qemu-devel/2017-02/msg05211.html
[3] http://lists.nongnu.org/archive/html/qemu-devel/2017-05/msg01499.html

Philippe Mathieu-Daudé (6):
  coccinelle: add a script to optimize tcg op using tcg_gen_extract()
  target/alpha: optimize cvtlq() using extract op
  target/arm: optimize rev16() using extract op
  target/m68k: optimize bcd_flags() using extract op
  target/ppc: optimize various functions using extract op
  target/sparc: optimize various functions using extract op

 scripts/coccinelle/tcg_gen_extract.cocci | 103 +++++++++++++++++++++++++++++++
 target/alpha/translate.c                 |   3 +-
 target/arm/translate-a64.c               |   6 +-
 target/m68k/translate.c                  |   3 +-
 target/ppc/translate.c                   |  21 +++----
 target/ppc/translate/vsx-impl.inc.c      |  24 +++----
 target/sparc/translate.c                 |  15 ++---
 7 files changed, 127 insertions(+), 48 deletions(-)
 create mode 100644 scripts/coccinelle/tcg_gen_extract.cocci

-- 
2.11.0