[3.4 PATCH] Fix bitfield-- != 0 transformation in fold-const.c

[Mark Mitchell]

Roger Sayle wrote:

>Hi Mark,
>
>The following patch is a backport of my recent mainline patch to
>fix the "bitfield-- != 0" -> "--bitfield != 1" optimization in fold.
>http://gcc.gnu.org/ml/gcc-patches/2004-03/msg00582.html
>
>This is a wrong-code regression from gcc 3.3 that has been latent
>for a while, but has been exposed by an unrelated change prior to
>branching for 3.4.
>
>The following patch has been tested against the gcc-3_4-branch on
>i686-pc-linux-gnu with a full bootstrap and regression tested with
>no new failures.  The only change relative to the mainline version
>is the use of "build" rather than "build2" (which is only on mainline).
>
>Ok for the gcc-3_4-branch?
>  
>
OK.

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Mark Mitchell
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