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[2018-07-22 22:32 UTC] php-bugs-2018 at ryandesign dot com
Description: ------------ PHP 7.3.0alpha4 fails to build on Mac OS X 10.6.8 running on a Mac with a 32-bit Intel processor. Here is a log from the MacPorts automated build system: https://build.macports.org/builders/ports-10.6_i386_legacy-builder/builds/45941/steps/install-port/logs/stdio The error is: Zend/zend_cpuinfo.c: In function ‘zend_cpu_startup’: Zend/zend_cpuinfo.c:33: error: can't find a register in class ‘BREG’ while reloading ‘asm’ Zend/zend_cpuinfo.c:33: error: can't find a register in class ‘BREG’ while reloading ‘asm’ Zend/zend_cpuinfo.c:33: error: can't find a register in class ‘BREG’ while reloading ‘asm’ Zend/zend_cpuinfo.c:33: error: ‘asm’ operand has impossible constraints Zend/zend_cpuinfo.c:33: error: ‘asm’ operand has impossible constraints Zend/zend_cpuinfo.c:33: error: ‘asm’ operand has impossible constraints {standard input}:27:non-relocatable subtraction expression, "_cpuinfo" minus "L00000000001$pb" {standard input}:27:symbol: "_cpuinfo" can't be undefined in a subtraction expression {standard input}:21:non-relocatable subtraction expression, "_cpuinfo" minus "L00000000001$pb" {standard input}:21:symbol: "_cpuinfo" can't be undefined in a subtraction expression {standard input}:13:non-relocatable subtraction expression, "_cpuinfo" minus "L00000000001$pb" {standard input}:13:symbol: "_cpuinfo" can't be undefined in a subtraction expression make: *** [Zend/zend_cpuinfo.lo] Error 1 This is a regression; PHP 7.2 and earlier built fine on Macs with 32-bit Intel processors. PHP 7.3.0alpha4 builds fine on Mac OS X 10.6.8 and later on a Mac with a 64-bit Intel processor, and on Mac OS X 10.5.8 on a Mac with a 32-bit PowerPC processor. Patcheszend_cpuinfo.c.patch (last revision 2018-11-15 09:18 UTC by php-bugs-2018 at ryandesign dot com)Pull RequestsHistoryAllCommentsChangesGit/SVN commits
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I've attached a patch that compiles for me, on 32-bit Mac OS X 10.6. What I've learned is that gcc 4.2 (at least the Apple-modified version shipped in old Xcode) uses position-independent code (PIC) by default, and that on i386 this compiler uses the %ebx register to store the PIC global offset table, but the cpuid opcode overwrites %ebx, hence the error. So %ebx needs to be preserved before calling cpuid and restored afterward. I've modeled my patch on the method used by cpuid.h from Xcode 5.1.1 on OS X 10.8, which is as follows: /* PIC on i386 uses %ebx, so preserve it. */ #if __i386__ #define __cpuid(__level, __eax, __ebx, __ecx, __edx) \ __asm(" pushl %%ebx\n" \ " cpuid\n" \ " mov %%ebx,%1\n" \ " popl %%ebx" \ : "=a"(__eax), "=r" (__ebx), "=c"(__ecx), "=d"(__edx) \ : "0"(__level)) #define __cpuid_count(__level, __count, __eax, __ebx, __ecx, __edx) \ __asm(" pushl %%ebx\n" \ " cpuid\n" \ " mov %%ebx,%1\n" \ " popl %%ebx" \ : "=a"(__eax), "=r" (__ebx), "=c"(__ecx), "=d"(__edx) \ : "0"(__level), "2"(__count)) #else #define __cpuid(__level, __eax, __ebx, __ecx, __edx) \ __asm("cpuid" : "=a"(__eax), "=b" (__ebx), "=c"(__ecx), "=d"(__edx) \ : "0"(__level)) #define __cpuid_count(__level, __count, __eax, __ebx, __ecx, __edx) \ __asm("cpuid" : "=a"(__eax), "=b" (__ebx), "=c"(__ecx), "=d"(__edx) \ : "0"(__level), "2"(__count)) #endif It seems that cpuid.h is closely tied to and belongs with a particular compiler. The cpuid.h from Xcode 9.4.1 on macOS 10.13 does it differently, for example, but that's for a much more recent version of clang. And since this code in PHP is only going to be used by compilers that don't provide a cpuid.h, maybe using this old implementation is the correct thing to do. With my patch it compiles, but I don't know if the result is correct. I don't know how this command is used within PHP. Is there a PHP command I should run, or a particular test in the test suite that I should look at, to verify it's working right?