Re: [PATCH] Use -fno-unit-at-a-time if gcc supports it

From: Robert Love
Date: Fri Sep 05 2003 - 11:08:14 EST


On Fri, 2003-09-05 at 11:17, Andreas Jaeger wrote:


> Since unit-at-a-time has better inlining heuristics the better way is
> to add the used attribute - but that takes some time. The short-term
> solution would be to add the compiler flag,

Won't we get a linker error if a static symbol is used but
optimized-away? It shouldn't be hard to fix the n linker errors that
crop up.

And why are we using static symbols in inline assembly outside of the
compilation scope?

Anyhow, if it generates an error, this isn't hard to fix.

Here is the start...

Robert Love


--- linux-rml/include/linux/compiler.h Fri Sep 5 11:57:56 2003
+++ linux/include/linux/compiler.h Fri Sep 5 12:02:02 2003
@@ -74,6 +74,19 @@
#define __attribute_pure__ /* unimplemented */
#endif

+/*
+ * As of gcc 3.2, we can mark a function as 'used' and gcc will assume that,
+ * even if it does not find a reference to it in any compilation unit. We
+ * need this for gcc 3.4 and beyond, which can optimize on a program-wide
+ * scope, and not just one file at a time, to avoid static symbols being
+ * discarded.
+ */
+#if (__GNUC__ == 3 && __GNUC_MINOR__ > 1) || __GNUC__ > 3
+#define __attribute_used__ __attribute__((used))
+#else
+#define __attribute_used__ /* unimplemented */
+#endif
+
/* This macro obfuscates arithmetic on a variable address so that gcc
shouldn't recognize the original var, and make assumptions about it */
#define RELOC_HIDE(ptr, off) \


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/