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Re: -ffast-math and floating point reordering
- From: Chris Lattner <sabre at nondot dot org>
- To: Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>
- Cc: Diego Novillo <dnovillo at redhat dot com>,Joe Buck <Joe dot Buck at synopsys dot com>, Jeff Law <law at redhat dot com>,<gcc at gcc dot gnu dot org>
- Date: Fri, 26 Mar 2004 14:23:25 -0600 (CST)
- Subject: Re: -ffast-math and floating point reordering
On Fri, 26 Mar 2004, Chris Lattner wrote:
> Okay, first, you must understand that LLVM is under vastly different
> constraints than GCC is. It makes little sense to have a -ffast-math mode
> in LLVM. What would happen when you link two .o files with different
> settings? At best the flag would just be cleared.
Oh, one other thing that I should have pointed out: when LLVM has support
for this, the C front-end will turn floating point adds into the strictadd
by default. If -ffast-math is presented to the C front-end, the C
front-end will generate the non-strict adds instead. This allows us to
use the *information* from the -ffast-math flag, without having to
actually preserve it in the LLVM files.
-Chris
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