[LLVMbugs] [Bug 9614] New: clang generates endless loop

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=9614

           Summary: clang generates endless loop
           Product: clang
           Version: trunk
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
        AssignedTo: unassignedclangbugs at nondot.org
        ReportedBy: kolesen.a at gmail.com
                CC: llvmbugs at cs.uiuc.edu


Clang generates llvm intermediate code with an endless loop, when -O is used.
Here is source .c code:

$ cat test.c
#include <wchar.h>
int main ()
{
    return btowc ('\0');
}


And after compilation we have:

(gdb) disas main
Dump of assembler code for function main:
   0x00000000004004f0 <+0>:    jmp    0x4004f0 <main>
End of assembler dump.


Here is LLVM IR:

$ clang -S -emit-llvm test.c; cat test.s
; ModuleID = 'test.c'
target datalayout =
"e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-pc-linux-gnu"

define i32 @main() nounwind {
  %1 = alloca i32, align 4
  store i32 0, i32* %1
  %2 = call i32 @btowc(i32 0) nounwind
  ret i32 %2
}

declare i32 @btowc(i32) nounwind



$ clang -O -S -emit-llvm test.c; cat test.s
; ModuleID = 'test.c'
target datalayout =
"e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-pc-linux-gnu"

define i32 @main() nounwind readnone {
  br label %tailrecurse.i

tailrecurse.i:                                    ; preds = %tailrecurse.i, %0
  br label %tailrecurse.i
}


I've attached wchar.h just in case.

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