[LLVMbugs] [Bug 1764] New: using global symbols in asm with -O1/-Os leads to ' symbol already defined' error

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=1764

           Summary: using global symbols in asm with -O1/-Os leads to
                    'symbol already defined' error
           Product: new-bugs
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: new bugs
        AssignedTo: unassignedbugs at nondot.org
        ReportedBy: edwintorok at gmail.com
                CC: llvmbugs at cs.uiuc.edu


Testcase is from kernel/sched.c, when I compile I get an error that
thread_return is already defined.

I am using llvm-gcc and llvm from latest svn version r43663 on x86-64.

$ llvm-gcc -O1  -c testcase-min.i -o foo.bc
/tmp/cck288u7.s: Assembler messages:
/tmp/cck288u7.s:56: Error: symbol `thread_return' is already defined

$ llvm-gcc -Os  -c testcase-min.i -o foo.bc
/tmp/cck288u7.s: Assembler messages:
/tmp/cck288u7.s:56: Error: symbol `thread_return' is already defined

$ llvm-gcc -O0  -c testcase-min.i -o foo.bc

Error is not reproducible if I compile to bitcode, and the optimize/codegen, or
just codegen.

cat testcase-min.i:

 typedef unsigned int __u32;
     struct x8664_pda {
     struct task_struct *pcurrent;
    }
     ;
     struct thread_info {
     __u32 flags;
    };
     struct thread_struct {
     unsigned long rsp;
    }
     __attribute__((aligned(16)));
     struct list_head {
    };
     struct task_struct {
     void *stack;
     struct mm_struct *mm, *active_mm;
     struct thread_struct thread;
    };
     struct rq {
     struct task_struct *curr, *idle;
    };
     static __typeof__(struct rq) per_cpu__runqueues;
     static inline __attribute__((always_inline)) void context_switch(struct rq
*rq, struct task_struct *prev,         struct task_struct *next) {
     if (__builtin_expect(!!(!prev->mm), 0)) {
     prev->active_mm = ((void *)0);
    }
     asm volatile("pushf ; pushq %%rbp ; movq %%rsi,%%rbp\n\t" "movq
%%rsp,%P[threadrsp](%[prev])\n\t" "movq %P[threadrsp](%[next]),%%rsp\n\t" "call
__switch_to\n\t" ".globl thread_return\n" "thread_return:\n\t" "movq
%%gs:%P[pda_pcurrent],%%rsi\n\t" "movq %P[thread_info](%%rsi),%%r8\n\t" "" "btr
 %[tif_fork],%P[ti_flags](%%r8)\n\t" "movq %%rax,%%rdi\n\t" "jc  
ret_from_fork\n\t" "movq %%rbp,%%rsi ; popq %%rbp ; popf\t" : "=a" (prev) :
[next] "S" (next), [prev] "D" (prev), [threadrsp] "i"
(__builtin_offsetof(struct task_struct,thread.rsp)), [ti_flags] "i"
(__builtin_offsetof(struct thread_info,flags)), [tif_fork] "i" (18),
[thread_info] "i" (__builtin_offsetof(struct task_struct,stack)),
[pda_pcurrent] "i" (__builtin_offsetof(struct x8664_pda,pcurrent)) : "memory",
"cc" ,"rcx","rbx","rdx","r8","r9","r10","r11","r12","r13","r14","r15");
    }
      void __attribute__((__section__(".sched.text"))) schedule(void) {
     struct task_struct *prev, *next;
     struct rq *rq;
     int cpu;
     rq = (&(*((void)((cpu)), &per_cpu__runqueues)));
     prev = rq->curr;
     if (__builtin_expect(!!(prev != next), 1)) {
     context_switch(rq, prev, next);
    }
    }


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