Building GCC & CFLAGS settings

Basile Starynkevitch
Wed May 5 19:41:00 GMT 2010

On 05/05/2010 07:42 PM, H.J. Lu wrote:
> On Wed, May 5, 2010 at 10:18 AM, Steve Ellcey<>  wrote:
>> I was wondering if anyone has built GCC using a CFLAGS (and CXXFLAGS) setting
>> that causes GCC to generate code that is not compatibile with the default
>> GCC output.
> I am using
> # CC="gcc -m32" CXX="g++ -m32" ...../configure ....
> to bootstrap 32bit gcc on 64bit Linux.

Out of curiosity, H.J.Lu, is it for performance reasons (like eg. 
bootstrapping in 32 bits mode is faster) or is it for testing reasons 
(like you are working on x86 32 bits backend)?

I was imagining that bootstrapping in 64 bits mode would be faster (more 
registers at run time of the compiler and less pressure on the register 
allocator at compile time of the compiler)

When I was bootstrapping a 32 bits GCC, I used to do that in a chroot-ed 
environment (containing a minimal debian x86 32bits distro).


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