Re: Using "-O1 -g" to debug optimisation bugs in Mingw.

[John Darrington]

Another thing you might try:  from the GCC manual, -O1 is equivalent
to :
          -fdefer-pop
          -fdelayed-branch
          -fguess-branch-probability
          -fcprop-registers
          -floop-optimize
          -fif-conversion
          -fif-conversion2
          -ftree-ccp
          -ftree-dce
          -ftree-dominator-opts
          -ftree-dse
          -ftree-ter
          -ftree-lrs
          -ftree-sra
          -ftree-copyrename
          -ftree-fre
          -ftree-ch
          -fmerge-constants

So it might be worth trying to find the minimal combination of these
flags which exhibit the problem.

J'




On Wed, Apr 04, 2007 at 12:11:04AM +0800, John McCabe-Dansted wrote:
     I've mentioned previously many of the bugs in the Mingw port go away
     if we compile with -O0.
     
     Most of them come back if we compile with -O1. I understand that O1
     code is meant to be reasonable to debug, so we may be able to diagnose
     those problems by debugging code generated with "-O1 -g".
     
     I intend to (as John D suggested offlist) also write a script to
     change the compile options on each .o file and see which ones seem to
     be causing the bugs.
     

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