[LLVMbugs] [Bug 20347] New: 16-bit and 32-bit immediates print as 64-bits in annotated assembly (x86-64)

[bugzilla-daemon at llvm.org]

http://llvm.org/bugs/show_bug.cgi?id=20347

            Bug ID: 20347
           Summary: 16-bit and 32-bit immediates print as 64-bits in
                    annotated assembly (x86-64)
           Product: tools
           Version: trunk
          Hardware: PC
                OS: All
            Status: NEW
          Severity: normal
          Priority: P
         Component: llc
          Assignee: unassignedbugs at nondot.org
          Reporter: spatel+llvm at rotateright.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

Using llc built from r213097:

$ cat imm.ll
define i8 @int8() #0 {
  ret i8 -128
}
define i16 @int16() #0 {
  ret i16 -32768
}
define i32 @int32() #0 {
  ret i32 -2147483648
}
define i64 @int64() #0 {
  ret i64 -9223372036854775808
}

---------------------------------------------------------------

$ ./llc imm.ll -o -  
(irrelevant output removed)
    movb    $-128, %al
    movw    $-32768, %ax            ## imm = 0xFFFFFFFFFFFF8000
    movl    $-2147483648, %eax      ## imm = 0xFFFFFFFF80000000
    movabsq    $-9223372036854775808, %rax ## imm = 0x8000000000000000

---------------------------------------------------------------

It's good to show decimal immediates as hex values when reading asm, but it's
confusing to see known 16-bit and 32-bit values displayed as sign extended
64-bit hex. 

Can we display immediates with the correct size? For completeness, shouldn't
the 8-bit value also be displayed in hex?

I think this is x86-specific because I don't see any attempt to print
immediates in hex when displaying ARM or PPC64 asm.

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