a9bc692d99
The xlc compiler seems to behave in a different way that gcc when it
comes the inline asm. There were two problems with the code with xlc:
- The TOC read in mca_patcher_base_patch_hook used the syntax
register unsigned long toc asm("r2") to read $r2 (the TOC
pointer). With gcc this seems to behave as expected but with xlc
the result in toc is not the same as $r2. I updated the code to use
asm volatile ("std 2, %0" : "=m" (toc)) to load the TOC pointer.
- The OPAL_PATCHER_BEGIN macro is meant to be the first thing in a
hook. On PPC64 it loads the correct TOC pointer (thanks to
mca_patcher_base_patch_hook) and saves the old one. The
OPAL_PATCHER_END macro restores the TOC pointer. Because we *need*
the TOC to be correct before it is accessed in the hook the
OPAL_PATCHER_BEGIN macro MUST come first. We did this and all was
well with gcc. With xlc on the other hand there was a TOC access
before the assembly inserted by OPAL_PATCHER_BEGIN. To fix this
quickly I broke each hook into a pair of function with the
OPAL_PATCHER_* macros on the top level functions. This works around
the issue but is not a clean way to fix this. In the future we
should 1) either update overwrite to not need this, or 2) figure
out why xlc is not inserting the asm before the first TOC read.
This fixes open-mpi/ompi#1854
Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
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| .. | ||
| base | ||
| linux | ||
| overwrite | ||
| Makefile.am | ||
| patcher.h | ||