id	summary	reporter	owner	description	type	status	priority	milestone	component	resolution	keywords	cc	phab_field
2675	x86_x64.cpp fails to build with -fpie on i386	pstumpf		"The cpuid assembler stuff does not compile when using PIE on i386 due to register constraints.  One must save and restore the PIC register (%ebx) before and after the call.  See also cpuid.h as provided by GCC or Clang.

In all other cases (amd64 and !PIE i386), use the regular code.

Compile and runtime tested on OpenBSD/i386, which uses -fpie by default.

--- x86_x64.cpp.orig.port       Tue Dec 27 15:12:31 2011
+++ x86_x64.cpp Sun Jul 13 22:47:33 2014
@@ -49,10 +49,20 @@
 #if defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 150030729
 // VC10+ and VC9 SP1: __cpuidex is already available
 #elif GCC_VERSION
+# if defined(__i386__) && defined(__PIC__)
 # define __cpuidex(regsArray, level, index)\
+       __asm__ __volatile__ (""pushl    %%ebx\n"" \
+       "" cpuid\n""\
+       ""mov %%ebx,%1\n"" \
+       ""popl %%ebx"" \
+       : ""=a"" ((regsArray)[0]), ""=r"" ((regsArray)[1]), ""=c"" ((regsArray)[2]), ""=d"" ((regsArray)[3])\
+       : ""0"" (level), ""2"" (index));
+# else
+# define __cpuidex(regsArray, level, index)\
        __asm__ __volatile__ (""cpuid""\
        : ""=a"" ((regsArray)[0]), ""=b"" ((regsArray)[1]), ""=c"" ((regsArray)[2]), ""=d"" ((regsArray)[3])\
        : ""0"" (level), ""2"" (index));
+# endif
 #else
 # error ""compiler not supported""
 #endif"	defect	new	Should Have	Backlog	Core engine