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author | ed <ed@FreeBSD.org> | 2012-01-12 16:51:56 +0000 |
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committer | ed <ed@FreeBSD.org> | 2012-01-12 16:51:56 +0000 |
commit | 94559e606b15db08a975854c515ae01cc8cfdb46 (patch) | |
tree | 8cbb11907e7e05bd2635155b5bd20296bd807099 /contrib/compiler-rt | |
parent | 7f1af3a6975c6fca211fc193f24247f34aea9ae5 (diff) | |
download | FreeBSD-src-94559e606b15db08a975854c515ae01cc8cfdb46.zip FreeBSD-src-94559e606b15db08a975854c515ae01cc8cfdb46.tar.gz |
Add a workaround to prevent endless recursion in compiler-rt.
SPARC and MIPS CPUs don't have special instructions to count
leading/trailing zeroes. The compiler-rt library provides fallback
rountines for these. The 64-bit routines, __clzdi2 and __ctzdi2, are
implemented as simple wrappers around the compiler built-in
__builtin_clz(), assuming these will expand to either 32-bit
CPU instructions or calls to __clzsi2 and __ctzsi2.
Unfortunately, our GCC 4.2 probably thinks that because the operand is
stored in a 64-bit register, it might just be a better idea to invoke
its 64-bit equivalent, simply resulting into endless recursion. Fix this
by defining __builtin_clz and __builtin_ctz to __clzsi2 and __ctzsi2
explicitly.
Diffstat (limited to 'contrib/compiler-rt')
-rw-r--r-- | contrib/compiler-rt/lib/int_lib.h | 20 |
1 files changed, 20 insertions, 0 deletions
diff --git a/contrib/compiler-rt/lib/int_lib.h b/contrib/compiler-rt/lib/int_lib.h index a87426c..2328a1d 100644 --- a/contrib/compiler-rt/lib/int_lib.h +++ b/contrib/compiler-rt/lib/int_lib.h @@ -43,4 +43,24 @@ /* Include internal utility function declarations. */ #include "int_util.h" +/* + * Workaround for LLVM bug 11663. Prevent endless recursion in + * __c?zdi2(), where calls to __builtin_c?z() are expanded to + * __c?zdi2() instead of __c?zsi2(). + * + * Instead of placing this workaround in c?zdi2.c, put it in this + * global header to prevent other C files from making the detour + * through __c?zdi2() as well. + * + * This problem has only been observed on FreeBSD for sparc64 and + * mips64 with GCC 4.2.1. + */ +#if defined(__FreeBSD__) && (defined(__sparc64__) || \ + defined(__mips_n64) || defined(__mips_o64)) +si_int __clzsi2(si_int); +si_int __ctzsi2(si_int); +#define __builtin_clz __clzsi2 +#define __builtin_ctz __ctzsi2 +#endif + #endif /* INT_LIB_H */ |