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author | Xavier Leroy <xavier.leroy@inria.fr> | 2016-10-04 15:52:16 +0200 |
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committer | Xavier Leroy <xavier.leroy@inria.fr> | 2016-10-04 15:52:16 +0200 |
commit | d2af79a77ed2936ff0ed90cadf8e48637d774d4c (patch) | |
tree | 09300943e12a98ae80598c79d455b31725271ead /runtime/powerpc/i64_umul.s | |
parent | a44893028eb1dd434c68001234ad56d030205a8e (diff) | |
download | compcert-d2af79a77ed2936ff0ed90cadf8e48637d774d4c.tar.gz compcert-d2af79a77ed2936ff0ed90cadf8e48637d774d4c.zip |
Turn 64-bit integer division and modulus by constants into multiply-high
This trick was already implemented for 32-bit integer division and modulus. Here we extend it to the 64-bit case.
For 32-bit target processors, the runtime library must implement 64-bit multiply-high (signed and unsigned). Tentative implementations are provided for IA32 and PowerPC, but need testing.
Diffstat (limited to 'runtime/powerpc/i64_umul.s')
-rw-r--r-- | runtime/powerpc/i64_umul.s | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/runtime/powerpc/i64_umul.s b/runtime/powerpc/i64_umul.s new file mode 100644 index 00000000..e734b93c --- /dev/null +++ b/runtime/powerpc/i64_umul.s @@ -0,0 +1,64 @@ +# ***************************************************************** +# +# The Compcert verified compiler +# +# Xavier Leroy, INRIA Paris +# +# Copyright (c) 2016 Institut National de Recherche en Informatique et +# en Automatique. +# +# Redistribution and use in source and binary forms, with or without +# modification, are permitted provided that the following conditions are met: +# * Redistributions of source code must retain the above copyright +# notice, this list of conditions and the following disclaimer. +# * Redistributions in binary form must reproduce the above copyright +# notice, this list of conditions and the following disclaimer in the +# documentation and/or other materials provided with the distribution. +# * Neither the name of the <organization> nor the +# names of its contributors may be used to endorse or promote products +# derived from this software without specific prior written permission. +# +# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS +# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT +# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR +# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT +# HOLDER> BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, +# EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +# PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR +# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF +# LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING +# NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS +# SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +# +# ********************************************************************* + +# Helper functions for 64-bit integer arithmetic. PowerPC version. + + .text + +# Unsigned multiply high + +# Reference C implementation in ../c/i64_umul.c + + .balign 16 + .globl __i64_umulh +__i64_umulh: + # u1 in r3; u0 in r4; v1 in r5; v0 in r6 + mulhwu r0, r4, r6 # k (in r0) = high((u64) u0 * (u64) v0) + mullw r8, r3, r6 + mulhwu r7, r3, r6 # t (in r8:r7) = (u64) u1 * (u64) v0 + addc r0, r8, r0 # w1 (in r0) = low (t + k) + addze r9, r7 # w2 (in r9) = high (t + k) + mullw r8, r4, r5 + mulhwu r7, r4, r5 # t (in r8:r7) = (u64) u0 * (u64) v1 + addc r0, r8, r0 # tmp (in r0) = low (t + w1) + addze r0, r7 # k (in r0) = high(t + w1) + mullw r8, r3, r5 + mulhwu r7, r3, r5 # t (in r8:r7) = (u64) u1 * (u64) v1 + addc r4, r8, r9 # add w2 + addze r3, r7 + addc r4, r4, r0 # add k + addze r3, r3 + blr + .type __i64_umulh, @function + .size __i64_umulh, .-__i64_umulh |