assert((call[0] == 0x40 || call[0] == 0x41) && call[1] == 0xFF)

[Vladimir Kozlov]

Hi,

I think next assert is incorrect:

#  Internal Error 
(/export/kvn/build/AOT/121714/hotspot/src/cpu/x86/vm/graalCodeInstaller_x86.cpp:45), 
pid=11105, tid=2
#  assert((call[0] == 0x40 || call[0] == 0x41) && call[1] == 0xFF) 
failed: expected call with rex/rexb prefix byte
#

According to Intel's manual in 64-bit mode near calls don't need REX 
prefix if first GP registers are used. And we follow it:

     private int prefixAndEncode(int regEnc, boolean byteinst) {
         if (regEnc >= 8) {
             emitByte(Prefix.REXB);
             return regEnc - 8;
         } else if (byteinst && regEnc >= 4) {
             emitByte(Prefix.REX);
         }
         return regEnc;
     }

     public final void call(Register src) {
         int encode = prefixAndEncode(src.encoding);
         emitByte(0xFF);
         emitByte(0xD0 | encode);
     }


I hit the assert when RAX is used for destination:

0xfffffd7fe50a1e10:     movq     $0x0000000000000000,%rax
0xfffffd7fe50a1e1a:     call     *%eax

So why you expect the call should have REX? Do you have somewhere 
hard-coded registers used for calls and don't expect RAX?

Thanks,
Vladimir