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Re: divmod, div, mod

From: Ian Lance Taylor <iant at google dot com>
To: Florent DEFAY <spira dot inhabitant at gmail dot com>
Cc: gcc-help at gcc dot gnu dot org
Date: Tue, 31 Mar 2009 07:28:03 -0700
Subject: Re: divmod, div, mod
References: <8502af3c0903310303j4f31065dm343c75c7cb2da5c1@mail.gmail.com>

Florent DEFAY <spira.inhabitant@gmail.com> writes:

> My question is:
> should I implement umodhi3 and udivhi3 and include them in libgcc so
> __divsi3 is alright,
> or should I implement divmodsi4 to override __divsi3 and __modsi3?

It's a question of runtime efficiency.  If it is faster to compute just
the quotient or the remainder, then implement __divsi3 and __modsi3 in
libgcc.  If the processor gives you both the quotient and the remainder
at the same time, then implement the udivmodsi4 insn in the MD file
(e.g., avr.md).

Ian

References:
- divmod, div, mod
  - From: Florent DEFAY

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