Re: How can I get VRP information for an RTX?

[David Daney <ddaney at avtrex dot com>]

Andrew Pinski wrote:
> On 4/1/07, David Daney <ddaney@avtrex.com> wrote:
> > I am looking at how the MIPS backend handles division.  For the compiler
> > configuration in question (mipsel-linux) division operations trap on
> > division by zero.  This is handled in mips_output_division in mips.c
> > where we unconditionally emit a conditional trap.
>
> Why does the back-end emit a trap for divide by zero if the hardware
> does not handle it?  Division by zero is undefined by the C/C++
> standard so maybe you should just add an option to the MIPS back-end
> not to emit the trap.
There *is* such an option.

The issue is that for some things (the java front-end) we need the 
trapping behavior.  I just want to optimize it if the divisor is known 
to be non-zero.  VRP knows, but by the time we generate the code it 
seems that we have forgotten.

David Daney