[LLVMbugs] [Bug 6930] New: clang: invalid input constraint "p" in asm

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=6930

           Summary: clang: invalid input constraint "p" in asm
           Product: new-bugs
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: edwintorok at gmail.com
                CC: llvmbugs at cs.uiuc.edu
            Blocks: 4068


An error when compiling the Linux kernel:

In file included from arch/x86/kernel/asm-offsets.c:4:                          
In file included from arch/x86/kernel/asm-offsets_64.c:8:                       
In file included from include/linux/crypto.h:20:                                
In file included from
/home/edwin/builds/linux-2.6/arch/x86/include/asm/atomic.h:6:  
In file included from
/home/edwin/builds/linux-2.6/arch/x86/include/asm/processor.h:15:
/home/edwin/builds/linux-2.6/arch/x86/include/asm/current.h:14:9: error:
invalid input constraint 'p' in asm
        return percpu_read_stable(current_task);                                
               ^                                                                
In file included from arch/x86/kernel/asm-offsets.c:4:                          
In file included from arch/x86/kernel/asm-offsets_64.c:8:                       
In file included from include/linux/crypto.h:20:                                
In file included from
/home/edwin/builds/linux-2.6/arch/x86/include/asm/atomic.h:6:                   
In file included from
/home/edwin/builds/linux-2.6/arch/x86/include/asm/processor.h:15:               
In file included from
/home/edwin/builds/linux-2.6/arch/x86/include/asm/current.h:5:                  
/home/edwin/builds/linux-2.6/arch/x86/include/asm/percpu.h:203:34: note:
instantiated from:                                   
#define percpu_read_stable(var)         percpu_from_op("mov", var, "p"
(&(var)))                                              
                                        ^                                       
In file included from arch/x86/kernel/asm-offsets.c:4:                          
In file included from arch/x86/kernel/asm-offsets_64.c:8:                       
In file included from include/linux/crypto.h:20:                                
In file included from
/home/edwin/builds/linux-2.6/arch/x86/include/asm/atomic.h:6:                   
In file included from
/home/edwin/builds/linux-2.6/arch/x86/include/asm/processor.h:15:               
/home/edwin/builds/linux-2.6/arch/x86/include/asm/current.h:14:9: note:
instantiated from:                                    
        return percpu_read_stable(current_task);                                
               ^                                                  

The rationale for using "p" is described very nicely in the git commit:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=ed8d9adf357ec331603fa1049510399812cea7e5

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