Subject: Re: Powerpc signal handler with floating point registers
To: Matt Thomas <firstname.lastname@example.org>
From: David Edelsohn <email@example.com>
Date: 02/28/2005 18:12:37
>>>>> Matt Thomas writes:
Matt> That seems to be a rather big hammer to smash that fly. Any other
Matt> way to make moves not use FP? Allow floating point, but only if
Matt> the program is using floating point types.
No. Either you allow the compiler to use the FPU or you don't.
There is no safe and reliable way to implement the policy that you
request. The request of the compiler ultimately is inconsistent: you are
telling it to enable the the FPU and FPRs, but somehow "know" when you
really want it used. Expecting DWIM behavior will lead to problems.
GCC 4.0 will use the FPU less for this type of situation.
However, if the floating point machinery is enabled, there always is a
chance that an optimizing compiler will decide that it is profitable to
use the resource.