[LLVMbugs] [Bug 22813] New: AARCH32 asm("b %0":: "i" (3)) should issues a warning

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=22813

            Bug ID: 22813
           Summary: AARCH32 asm("b %0":: "i" (3)) should issues a warning
           Product: clang
           Version: 3.6
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: axelheider at gmx.de
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

follow up from the comments at bug #22761. with LLVM/Clang 3.6 targeting
ARCH322 this compiles without warnings/errors:

  __asm ("b %0":: "i" (0));     // 10000004:  ea000000   b 1000000c (+0x08)
  __asm ("b %0":: "i" (1));     // 10000008:  ea000000   b 10000010 (+0x08)
  __asm ("b %0":: "i" (2));     // 1000000c:  ea000000   b 10000014 (+0x08)
  __asm ("b %0":: "i" (3));     // 10000010:  ea000000   b 10000018 (+0x08)
  __asm ("b %0":: "i" (4));     // 10000014:  ea000001   b 10000020 (+0x0C)

But it silently clears out the lower two bits if they are not zero. This should
actually give a warning. In ARM mode any constant must be a multiple of 4, in
TUMB mode it must be a multiple of 2. Anything else cannot even be encoded in
the instruction. So at least a warning here would be nice, like is is done 
when targeting AARCH64 here

  __asm ("b %0":: "i" (0)); // ok for any multiple of 4

  __asm ("b %0":: "i" (1)); // error for any non-multiple of 4

   error: expected label or encodable integer pc offset
      __asm ("b %0":: "i" (1));

   <inline asm>:1:4: note: instantiated into assembly here
          b #1

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