[LLVMbugs] [Bug 24052] New: x86 assembly could be improved for expression x+9*y where x, y are int8_t

[bugzilla-daemon at llvm.org]

https://llvm.org/bugs/show_bug.cgi?id=24052

            Bug ID: 24052
           Summary: x86 assembly could be improved for expression x+9*y
                    where x,y are int8_t
           Product: new-bugs
           Version: 3.6
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: unassignedbugs at nondot.org
          Reporter: calixte.denizet at gmail.com
                CC: llvmbugs at cs.uiuc.edu
    Classification: Unclassified

The following C code:
int8_t foo(int8_t x, int8_t y)
{
    return x + 9 * y;
}

generates this assembly with clang:
movb    $9, %cl
movb    %sil, %al
mulb    %cl
addb    %al, %dil
movsbl    %dil, %eax

and generates this one with gcc:
leal    (%rsi,%rsi,8), %esi
leal    (%rsi,%rdi), %eax

For information it is ok when args are int32_t.

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20150707/e0893c2a/attachment.html>