Commit c99d6969 authored Jul 31, 2015 by Aurelien Jarno

tcg/mips: fix add2



The add2 code in the tcg_out_addsub2 function doesn't take into account
the case where rl == al == bl. In that case we can't compute the carry
after the addition. As it corresponds to a multiplication by 2, the
carry bit is the bit 31.

While this is a corner case, this prevents x86-64 guests to boot on a
MIPS host.

Cc: qemu-stable@nongnu.org
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

parent 3c8691f5

tcg/mips/tcg-target.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -1271,6 +1271,9 @@ static void tcg_out_addsub2(TCGContext *s, TCGReg rl, TCGReg rh, TCGReg al,
		if (cbl) {
		tcg_out_opc_imm(s, OPC_ADDIU, rl, al, bl);
		tcg_out_opc_imm(s, OPC_SLTIU, TCG_TMP0, rl, bl);
		} else if (rl == al && rl == bl) {
		tcg_out_opc_sa(s, OPC_SRL, TCG_TMP0, al, 31);
		tcg_out_opc_reg(s, OPC_ADDU, rl, al, bl);
		} else {
		tcg_out_opc_reg(s, OPC_ADDU, rl, al, bl);
		tcg_out_opc_reg(s, OPC_SLTU, TCG_TMP0, rl, (rl == bl ? al : bl));