Author: ed Date: Thu Jan 12 16:51:56 2012 New Revision: 230021 URL: http://svn.freebsd.org/changeset/base/230021
Log: 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. Modified: head/contrib/compiler-rt/lib/int_lib.h Modified: head/contrib/compiler-rt/lib/int_lib.h ============================================================================== --- head/contrib/compiler-rt/lib/int_lib.h Thu Jan 12 15:57:03 2012 (r230020) +++ head/contrib/compiler-rt/lib/int_lib.h Thu Jan 12 16:51:56 2012 (r230021) @@ -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 */ _______________________________________________ svn-src-all@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
