--- qemu/tcg/README 2018/04/24 18:25:07 1.1.1.3 +++ qemu/tcg/README 2018/04/24 18:34:51 1.1.1.4 @@ -75,11 +75,11 @@ destroyed, but local temporaries and glo * Helpers: Using the tcg_gen_helper_x_y it is possible to call any function -taking i32, i64 or pointer types. By default, before calling an helper, +taking i32, i64 or pointer types. By default, before calling a helper, all globals are stored at their canonical location and it is assumed -that the function can modify them. This can be overriden by the +that the function can modify them. This can be overridden by the TCG_CALL_CONST function modifier. By default, the helper is allowed to -modify the CPU state or raise an exception. This can be overriden by +modify the CPU state or raise an exception. This can be overridden by the TCG_CALL_PURE function modifier, in which case the call to the function is removed if the return value is not used. @@ -285,6 +285,20 @@ the four high order bytes are set to zer Indicate that the value of t0 won't be used later. It is useful to force dead code elimination. +* deposit_i32/i64 dest, t1, t2, pos, len + +Deposit T2 as a bitfield into T1, placing the result in DEST. +The bitfield is described by POS/LEN, which are immediate values: + + LEN - the length of the bitfield + POS - the position of the first bit, counting from the LSB + +For example, pos=8, len=4 indicates a 4-bit field at bit 8. +This operation would be equivalent to + + dest = (t1 & ~0x0f00) | ((t2 << 8) & 0x0f00) + + ********* Conditional moves * setcond_i32/i64 cond, dest, t1, t2 @@ -364,7 +378,7 @@ formed from two 32-bit arguments. The r ********* QEMU specific operations -* tb_exit t0 +* exit_tb t0 Exit the current TB and return the value t0 (word type). @@ -488,7 +502,7 @@ register. the speed of the translation. - Don't hesitate to use helpers for complicated or seldom used target - intructions. There is little performance advantage in using TCG to + instructions. There is little performance advantage in using TCG to implement target instructions taking more than about twenty TCG instructions.