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Re: Difference between two optimization settings
- From: Ian Lance Taylor <iant at google dot com>
- To: Thomas Heinz <thomasheinz at gmx dot net>
- Cc: Eljay Love-Jensen <eljay at adobe dot com>, GCC-help <gcc-help at gcc dot gnu dot org>
- Date: Sun, 29 Jun 2008 21:59:41 -0700
- Subject: Re: Difference between two optimization settings
- References: <C48BA3CD.6837%eljay@adobe.com> <200806281536.57864.thomasheinz@gmx.net>
Thomas Heinz <thomasheinz@gmx.net> writes:
> Do you (or someone else) know how to enable only constant propagation +
> constant folding in an -O0 optimization setting?
gcc does not support that.
> I guess it's necessary to tweak the code, isn't it?
> If so, how much effort would it be?
It would be non-trivial. The CCP pass in gcc uses SSA form. With -O0
SSA form is not generated.
Ian