Hello,
I have a more-than-passing interest in getting isel instruction
support for the e500 spec implemented. I have taken several days and
worked out what I believe is a valid implementation according to what
I understand of the e500 instruction set, and what I have learned
about valgrind.
The code works find for my simple test programs that include an isel
instruction, but fails on anything more complex.
The failure is a segfault shortly after processing of an isel
instruction (typically, several other isel instructions have
successfully executed before the failure). I am assuming that the
changes I made have somehow resulted in the isel instruction no longer
performing correctly.
If any of you have the time, could you take a look at my code snippet
and see if I have made a significant error somewhere?
/* isel : if crB then rD = rA else rD = rB
* 011111 DDDDD AAAAA BBBBB CCCCC 011110
* rD rA rB crb
* 21-25 16-20 11-15 6-10 0-5
*
*/
static Bool dis_int_isel ( UInt theInstr )
{
UChar rD_addr = ifieldRegDS(theInstr);
UChar rA_addr = ifieldRegA(theInstr);
UChar rB_addr = ifieldRegB(theInstr);
UChar cr_bit = ifieldRegC(theInstr);
IRType ty = mode64 ? Ity_I64 : Ity_I32;
IRTemp rD = newTemp(ty);
IRTemp rA = newTemp(ty);
IRTemp rB = newTemp(ty);
IRTemp cr = newTemp(ty);
IRTemp cc_bitset = newTemp(ty);
vex_printf("handling isel, rD %d rA %d rB %d crb %d\n", rD_addr,
rA_addr, rB_addr, cr_bit);
DIP("isel. r%u,r%u,r%u,crb%u\n", rD_addr, rA_addr, rB_addr, cr_bit);
assign( rA, getIReg(rA_addr) );
assign( rB, getIReg(rB_addr) );
assign( cr, getCRbit(cr_bit) );
assign( cc_bitset, binop(Iop_And32, mkexpr(cr), mkU32(1)));
assign( rD, IRExpr_Mux0X(
unop(Iop_1Uto8,
binop(Iop_CmpEQ32,
mkexpr(cc_bitset),
mkU32(0))),
mkexpr(rA),
mkexpr(rB)));
return True;
}
Much appreciated,
Aaron
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