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| author | Joshua Oreman | 2010-08-19 01:37:22 +0200 |
|---|---|---|
| committer | Michael Brown | 2010-08-19 14:37:52 +0200 |
| commit | 49d6f5700561be091b2b25bb7641708333e4911d (patch) | |
| tree | ac34755391ad3025d3fd817af3696d1bca3276cf /src/include/compiler.h | |
| parent | [build] Add tap.linux to "make everything" (diff) | |
| download | ipxe-49d6f5700561be091b2b25bb7641708333e4911d.tar.gz ipxe-49d6f5700561be091b2b25bb7641708333e4911d.tar.xz ipxe-49d6f5700561be091b2b25bb7641708333e4911d.zip | |
[compiler] Prevent empty weak function stubs from being removed
Even with the noinline specifier added by commit 1a260f8, gcc may skip
calls to non-inlinable functions that it knows have no side
effects. This caused the get_cached_dhcpack() call in start_dhcp(),
the weak stub of which has no code in its body, to be removed,
preventing cached DHCP from working.
Fix by adding a __keepme macro to compiler.h expanding to asm(""), as
recommended by gcc's info page, and using it in the weak stub for
get_cached_dhcpack().
Reported-by: Aaron Brooks <aaron@brooks1.net>
Tested-by: Aaron Brooks <aaron@brooks1.net>
Signed-off-by: Joshua Oreman <oremanj@rwcr.net>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Diffstat (limited to 'src/include/compiler.h')
| -rw-r--r-- | src/include/compiler.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/include/compiler.h b/src/include/compiler.h index 16165b36..738655af 100644 --- a/src/include/compiler.h +++ b/src/include/compiler.h @@ -191,6 +191,14 @@ REQUEST_EXPANDED ( CONFIG_SYMBOL ); */ #define __weak __attribute__ (( weak, noinline )) +/** Prevent a function from being optimized away without inlining + * + * Calls to functions with void return type that contain no code in their body + * may be removed by gcc's optimizer even when inlining is inhibited. Placing + * this macro in the body of the function prevents that from occurring. + */ +#define __keepme asm(""); + #endif /** @defgroup dbg Debugging infrastructure |