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Re: assemble code and disassembled code in-consistency

On 7/6/12 12:54 PM, H.J. Lu wrote:
On Fri, Jul 6, 2012 at 9:47 AM, H.J. Lu <> wrote:
On Fri, Jul 6, 2012 at 9:27 AM, Feng LI <> wrote:
Hi folks,

I have a backend hook (x86_64) for builtin function expansion, so
I have this:

expand_simple_binop (DImode, ASHIFT, op0,
                                 GEN_INT (32),op0,1,OPTAB_DIRECT);

to generate op0 = op0<<32 (op0 is the first argument of this builtin
function, with type SIZE_T)

The thing goes well in the assemble code, where I got:
         movq    104(%rbx), %rax
         salq    $32, %rax
         addq    80(%rbx), %rax

as expected.

But at execution time, it gives me a strange behavior,
So I disassemble the code,

401135:       48 8b 43 68             mov    0x68(%rbx),%rax
401140:       48 c1 e0 20             shl    $0x20,%rax
401144:       48 03 43 50             add    0x50(%rbx),%rax

and it turns out salq are changed to shl which leads to the
strange behavior. shl only allows shift less or equal than 31.

It is a binutils issue.
Hi Peter, Andi, Mark,

For some reason, binutils encodes sal the same as shl.  I'd
like to fix it.  Will it cause any problems?


SAL = SHL functionally. They are aliases. FWIW, XED does not even have SAL; I call them all SHL.

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