question about -fno-pre-inlining

[John Lato]

Hello,

I was experimenting with compiler flags trying to tune some
performance and got something unexpected with the -fno-pre-inlining
flag.  I was hoping somebody here might be able to clarify an issue
for me.

When compiled with -fno-pre-inlining, my test program gives a
different result than compiled without (0.988... :: Double, compared
to 1.0).  It's numerical code, and was originally compiled with
-fexcess-precision, however I have tried both with and without
-fexcess-precision and the results are the same.  The only other
compiler flags in use are -O2 and --make.  Is this expected behavior
or a possible bug?  I believe the value with -fno-pre-inlining is
correct (and runs about 30% faster too).

This was done on an OSX 10.5 Macbook with GHC-6.10.3.  I could check
this on some other systems if it would be helpful.

Sincerely,
John Lato