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Re: Need 32 bit supported GCC 4.9 debian binaries for Renesas SH7757 Processor

On 29 Jun 2015, at 20:16, John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de> wrote:

> On 06/29/2015 01:13 PM, Ritesh Prajapati wrote:
>>    Currently, We are using GCC 4.4.5 and We have to switch to GCC 4.9
>> as per requirement.
> Well, you can go ahead and use gcc-4.9. I wasn't saying that the
> compiler is completely broken. But you should just be aware that
> there *might* be problems with wrong code generation and I just
> advise you to use the latest version from SVN.

GCC 4.9 should be generally fine.  However, there are some known issues with it (as with every version...)

Some of the bugs can silently produce wrong code.  E.g. the option -mpretend-cmove is known to produce wrong code in some situations.  Its use is not recommended and it's disabled by default.  Some other bugs might result in an internal compiler error.  The most frequent one we've been hitting is a problem with the register allocator.  We're not sure whether there will a fix for GCC 4.9.  Starting from GCC 5 there's a new (undocumented transitional internal) option -mlra which uses a different register allocation approach, which solves some of the issues.

In any case, when using GCC for SH I'd highly recommend using the latest SVN revision for a release branch.  Currently maintained release branches are 4.9 and 5.x.


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