I am using the gnu assembler with intel syntax for the MIC and I am encountering a bug in its store addressing.
I want to move an interger from the FPU to the eax register and I am doing it by the following sequence of source:
sub rsp,8
fistp dword ptr [rsp]
mov eax,dword [rsp]
add rsp,8
I move the rsp in increments of 8 to ensure that alignment is maintained for the stack. The code assembles ok
The code that is generated by the assembler can be seen by gdb on the MIC
0x0000000000401037 <+65>: sub $0x8,%rsp
0x000000000040103b <+69>: fistpl (%rsp)
=> 0x000000000040103e <+72>: mov 0x4(%rsp),%eax
0x0000000000401042 <+76>: add $0x8,%rsp
it is now loading the eax register 4 on from the rsp
I was able to fix this by changing the source to
sub rsp,8
fistp dword ptr [rsp]
mov eax,dword ptr [rsp]
add rsp,8
but the assembler should either flag the absence of 'ptr' as an error or it should assemble it correctly.
