Hi, On Fri, Sep 17 2021, Kewen.Lin wrote: > on 2021/9/16 下午9:19, Martin Jambor wrote: >> On Thu, Sep 16 2021, Kewen.Lin wrote: >>> on 2021/9/15 下午8:51, Martin Jambor wrote: >>>> On Wed, Sep 08 2021, Kewen.Lin wrote: >>>>> >>>> >>>> [...] >>>> >>>>> diff --git a/gcc/ipa-fnsummary.h b/gcc/ipa-fnsummary.h >>>>> index 78399b0b9bb..300b8da4507 100644 >>>>> --- a/gcc/ipa-fnsummary.h >>>>> +++ b/gcc/ipa-fnsummary.h >>>>> @@ -193,6 +194,9 @@ public: >>>>> vec<ipa_freqcounting_predicate, va_gc> *loop_strides; >>>>> /* Parameters tested by builtin_constant_p. */ >>>>> vec<int, va_heap, vl_ptr> GTY((skip)) builtin_constant_p_parms; >>>>> + /* Like fp_expressions, but it's to hold some target specific >>>>> information, >>>>> + such as some target specific isa flags. */ >>>>> + auto_vec<HOST_WIDE_INT> GTY((skip)) target_info; >>>>> /* Estimated growth for inlining all copies of the function before >>>>> start >>>>> of small functions inlining. >>>>> This value will get out of date as the callers are duplicated, but >>>> >>>> Segher already wrote in the first thread that a vector of HOST_WIDE_INTs >>>> is an overkill and I agree. So at least make the new field just a >>>> HOST_WIDE_INT or better yet, an unsigned int. But I would even go >>>> further and make target_info only a 16-bit bit-field, place it after the >>>> other bit-fields in class ipa_fn_summary and pass it to the hooks as >>>> uint16_t. Unless you have plans which require more space, I think we >>>> should be conservative here. >>>> >>> >>> OK, yeah, the consideration is mainly for the scenario that target has >>> a few bits to care about. I just realized that to avoid inefficient >>> bitwise operation for mapping target info bits to isa_flag bits, target >>> can rearrange the sparse bits in isa_flag, so it's not a deal. >>> Thanks for re-raising this! I'll use the 16 bits bit-field in v3 as you >>> suggested, if you don't mind, I will put it before the existing bit-fields >>> to have a good alignment. >> >> All right. >> > > Sorry that I failed to use 16 bit-fields for this, I figured out that > the bit-fields can not be address-taken or passed as non-const reference. > The gentype also failed to recognize uint16_t if I used uint16_t directly > in ipa-fnsummary.h. Finally I used unsigned int instead. >
well, you could have used: unsigned int target_info : 16; for the field (and uint16_t when passed to hooks). But I am not sure if it is that crucial. Martin
