From: Richard Henderson <richard.henderson@linaro.org>
To: qemu-devel@nongnu.org
Cc: david@redhat.com
Subject: [PATCH v3 0/4] target/s390x: Improve carry computation
Date: Mon, 14 Dec 2020 16:13:52 -0600 [thread overview]
Message-ID: <20201214221356.68039-1-richard.henderson@linaro.org> (raw)
While testing the float128_muladd changes for s390x host,
emulating under x86_64 of course, I noticed that the code
we generate for strings of ALCGR and SLBGR is pretty awful.
I realized that we were missing a trick: the output cc is
based only on the output (result and carry) and so we don't
need to save the inputs. And once we do that, we can use
the output carry as a direct input to the next insn.
Changes for v3:
* Rebased.
Changes for v2:
* Add a few more comments, and enhance the patch descriptions.
r~
Richard Henderson (4):
target/s390x: Improve cc computation for ADD LOGICAL
target/s390x: Improve ADD LOGICAL WITH CARRY
target/s390x: Improve cc computation for SUBTRACT LOGICAL
target/s390x: Improve SUB LOGICAL WITH BORROW
target/s390x/internal.h | 11 +-
target/s390x/cc_helper.c | 123 +++-------------
target/s390x/helper.c | 10 +-
target/s390x/translate.c | 289 ++++++++++++++++++++-----------------
target/s390x/insn-data.def | 76 +++++-----
5 files changed, 216 insertions(+), 293 deletions(-)
--
2.25.1
next reply other threads:[~2020-12-14 22:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-14 22:13 Richard Henderson [this message]
2020-12-14 22:13 ` [PATCH v3 1/4] target/s390x: Improve cc computation for ADD LOGICAL Richard Henderson
2020-12-14 22:13 ` [PATCH v3 2/4] target/s390x: Improve ADD LOGICAL WITH CARRY Richard Henderson
2020-12-14 22:13 ` [PATCH v3 3/4] target/s390x: Improve cc computation for SUBTRACT LOGICAL Richard Henderson
2020-12-14 22:13 ` [PATCH v3 4/4] target/s390x: Improve SUB LOGICAL WITH BORROW Richard Henderson
2020-12-16 14:44 ` [PATCH v3 0/4] target/s390x: Improve carry computation David Hildenbrand
2020-12-16 17:09 ` Cornelia Huck
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