[Bug inline-asm/64119] asm triggers local register variable data corruption

adam at consulting dot net.nz gcc-bugzilla@gcc.gnu.org
Sun Nov 30 22:57:00 GMT 2014


https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64119

Adam Warner <adam at consulting dot net.nz> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|INVALID                     |FIXED

--- Comment #5 from Adam Warner <adam at consulting dot net.nz> ---
The documentation is not clear. But your explanation is fantastic. Thank you
Andrew.

It's a big step to fully comprehend that reassignment to a local register
variable in GCC *does not work* to again make the register live for dataflow
analysis. The approach GCC has chosen is one of maximum surprise.

Thank you for describing a workaround: "create a new local register variable
each time and GCC won't optimize them away."



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