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Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue
- From: rridge at csclub dot uwaterloo dot ca (Ross Ridge)
- To: gcc at gcc dot gnu dot org
- Date: Tue, 24 Nov 2009 17:04:57 +0000 (UTC)
- Subject: Re: [PATCH][GIT PULL][v2.6.32] tracing/x86: Add check to detect GCC messing with mcount prologue
Andrew Haley writes:
>Alright. So, it is possible in theory for gcc to generate code that
>only uses -maccumulate-outgoing-args when it needs to realign SP.
>And, therefore, we could have a nice option for the kernel: one with
>(mostly) good code density and never generates the bizarre code
>sequence in the prologue.
The best option would be for the Linux people to fix the underlying
problem in their kernel sources. If the code no longer requested
that certain automatic variables be aligned, then not only would this
bizarre code sequence not be emitted, the unnecessary stack alignment
would disapear as well. The kernel would then be free to choose to use
whatever code generation options it felt was appropriate.
Ross Ridge