| Message ID | 1372886968-17497-7-git-send-email-rth@twiddle.net |
|---|---|
| State | New |
| Headers | show |
On 3 July 2013 22:29, Richard Henderson <rth@twiddle.net> wrote: > This allows TCG_TARGET_HAS_* to be a variable rather than a constant, > which allows easier support for differing ISA levels for the host. The effect of this is that TCG_OPF_NOT_PRESENT means "if set, op is definitely not present; if not set, op might or might not be present", right? Which is OK because it's just a debug guard/sanity check. (That might be worth noting in a comment I guess.) Reviewed-by: Peter Maydell <peter.maydell@linaro.org> -- PMM
On 07/04/2013 03:53 AM, Peter Maydell wrote: > On 3 July 2013 22:29, Richard Henderson <rth@twiddle.net> wrote: >> This allows TCG_TARGET_HAS_* to be a variable rather than a constant, >> which allows easier support for differing ISA levels for the host. > > The effect of this is that TCG_OPF_NOT_PRESENT means "if set, > op is definitely not present; if not set, op might or might > not be present", right? Which is OK because it's just a debug > guard/sanity check. (That might be worth noting in a comment > I guess.) Well, if not set, an entry must be present in the operands table. E.g. for arm division, the { INDEX_op_div_i32, "r", "r", "r" } entry is always there, even if TCG_TARGET_HAS_div_i32 evaluates to false at runtime. The entry must be there Just In Case the expression might be true. r~
diff --git a/tcg/tcg-opc.h b/tcg/tcg-opc.h index 12967fb..c94e255 100644 --- a/tcg/tcg-opc.h +++ b/tcg/tcg-opc.h @@ -40,7 +40,7 @@ DEF(set_label, 0, 0, 1, TCG_OPF_BB_END) DEF(call, 0, 1, 2, TCG_OPF_CALL_CLOBBER) /* variable number of parameters */ DEF(br, 0, 0, 1, TCG_OPF_BB_END) -#define IMPL(X) (X ? 0 : TCG_OPF_NOT_PRESENT) +#define IMPL(X) (__builtin_constant_p(X) && !(X) ? TCG_OPF_NOT_PRESENT : 0) #if TCG_TARGET_REG_BITS == 32 # define IMPL64 TCG_OPF_64BIT | TCG_OPF_NOT_PRESENT #else
This allows TCG_TARGET_HAS_* to be a variable rather than a constant, which allows easier support for differing ISA levels for the host. Signed-off-by: Richard Henderson <rth@twiddle.net> --- tcg/tcg-opc.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)