bader added inline comments.
================ Comment at: lib/Headers/opencl-c.h:16020 +// The macro CLK_NULL_RESERVE_ID refers to an invalid reservation ID. +#define CLK_NULL_RESERVE_ID (__builtin_astype((void *)0, reserve_id_t)) bool __ovld is_valid_reserve_id(reserve_id_t reserve_id); ---------------- b-sumner wrote: > yaxunl wrote: > > bader wrote: > > > yaxunl wrote: > > > > bader wrote: > > > > > yaxunl wrote: > > > > > > bader wrote: > > > > > > > yaxunl wrote: > > > > > > > > yaxunl wrote: > > > > > > > > > bader wrote: > > > > > > > > > > yaxunl wrote: > > > > > > > > > > > Anastasia wrote: > > > > > > > > > > > > echuraev wrote: > > > > > > > > > > > > > yaxunl wrote: > > > > > > > > > > > > > > Anastasia wrote: > > > > > > > > > > > > > > > yaxunl wrote: > > > > > > > > > > > > > > > > Anastasia wrote: > > > > > > > > > > > > > > > > > Looks good from my side. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > @yaxunl , since you originally committed > > > > > > > > > > > > > > > > > this. Could you please verify that changing > > > > > > > > > > > > > > > > > from `SIZE_MAX` to `0` would be fine. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Btw, we have a similar definition for > > > > > > > > > > > > > > > > > `CLK_NULL_EVENT`. > > > > > > > > > > > > > > > > `__PIPE_RESERVE_ID_VALID_BIT` is implementation > > > > > > > > > > > > > > > > detail and not part of the spec. I would > > > > > > > > > > > > > > > > suggest to remove it from this header file. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > The spec only requires CLK_NULL_RESERVE_ID to > > > > > > > > > > > > > > > > be defined but does not define its value. > > > > > > > > > > > > > > > > Naturally a valid id starts from 0 and > > > > > > > > > > > > > > > > increases. I don't see significant advantage to > > > > > > > > > > > > > > > > change CLK_NULL_RESERVE_ID from __SIZE_MAX to 0. > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Is there any reason that this change is needed? > > > > > > > > > > > > > > > I don't see issues to commit things outside of > > > > > > > > > > > > > > > spec as soon as they prefixed properly with "__". > > > > > > > > > > > > > > > But I agree it would be nice to see if it's any > > > > > > > > > > > > > > > useful and what the motivation is for having > > > > > > > > > > > > > > > different implementation. > > > > > > > > > > > > > > For `__PIPE_RESERVE_ID_VALID_BIT`, it assumes that > > > > > > > > > > > > > > the implementation uses one specific bit of a > > > > > > > > > > > > > > reserve id to indicate that the reserve id is > > > > > > > > > > > > > > valid. Not all implementations assume that. > > > > > > > > > > > > > > Actually I am curious why that is needed too. > > > > > > > > > > > > > About `CLK_NULL_RESERVE_ID`: we check that reserve id > > > > > > > > > > > > > is valid if significant bit equal to one. > > > > > > > > > > > > > `CLK_NULL_RESERVE_ID refers to an invalid > > > > > > > > > > > > > reservation, so if `CLK_NULL_RESERVE_ID equal to 0, > > > > > > > > > > > > > we can be sure that significant bit doesn't equal to > > > > > > > > > > > > > 1 and it is invalid reserve id. Also it is more > > > > > > > > > > > > > obviously if CLK_**NULL**_RESERVE_ID is equal to 0. > > > > > > > > > > > > > > > > > > > > > > > > > > What about `__PIPE_RESERVE_ID_VALID_BIT`: As I > > > > > > > > > > > > > understand previous implementation also assumes that > > > > > > > > > > > > > one specific bit was of a reverse id was used to > > > > > > > > > > > > > indicate that the reserve id is valid. So, we just > > > > > > > > > > > > > increased reserve id size by one bit on 32-bit > > > > > > > > > > > > > platforms and by 33 bits on 64-bit platforms. > > > > > > > > > > > > It is more logical to me that `CLK_NULL_RESERVE_ID` is > > > > > > > > > > > > 0, but spec doesn't define it of course. > > > > > > > > > > > In our implementation, valid reserve id starts at 0 and > > > > > > > > > > > increasing linearly until `__SIZE_MAX-1`. This change > > > > > > > > > > > will break our implementation. > > > > > > > > > > > > > > > > > > > > > > However, we can modify our implementation to adopt this > > > > > > > > > > > change since it brings about benefits overall. > > > > > > > > > > Ideally it would be great to have unified implementation, > > > > > > > > > > but we can define device specific value for > > > > > > > > > > CLK_NULL_RESERVE_ID by using ifdef directive. > > > > > > > > > How about > > > > > > > > > > > > > > > > > > ``` > > > > > > > > > __attribute__((const)) size_t __clk_null_reserve_id(); > > > > > > > > > #define CLK_NULL_RESERVE_ID __clk_null_reserve_id() > > > > > > > > > > > > > > > > > > ``` > > > > > > > > > I think the spec does not require it to be compile time > > > > > > > > > constant. Then each library can implement its own > > > > > > > > > __clk_null_reserve_id() whereas the IR is target independent. > > > > > > > > Or we only do this for SPIR and define it as target specific > > > > > > > > value for other targets. > > > > > > > Defining CLK_NULL_RESERVE_ID as a function call should also work, > > > > > > > but IMHO compile time constant is preferable option. > > > > > > > I don't think making it compile time constant for SPIR only makes > > > > > > > sense to me - in this case we can use constant for all targets. > > > > > > > > > > > > > > How about following approach: use 0 by default and allow other > > > > > > > targets re-define CLK_NULL_RESERVE_ID value. > > > > > > > > > > > > > > ``` > > > > > > > #ifndef CLK_NULL_RESERVE_ID > > > > > > > #define CLK_NULL_RESERVE_ID 0 > > > > > > > #endif // CLK_NULL_RESERVE_ID > > > > > > > ``` > > > > > > > > > > > > > > If CLK_NULL_RESERVE_ID defined via -D command line option or > > > > > > > included before OpenCL C header file (via -include option), the > > > > > > > defined value will be used, otherwise 0. > > > > > > > > > > > > > > Will it work for you? > > > > > > No. That makes us unable to consume SPIR since CLK_NULL_RESERVE_ID > > > > > > is hardcoded as 0 when the source code is translated to SPIR > > > > > > whereas our target expects ~0U. > > > > > > > > > > > > To get a portable IR we need to represent CLK_NULL_RESERVE_ID as a > > > > > > function which can be lowered to a constant by a specific target. > > > > > > > > > > > > > > > > > Do you refer to SPIR-V or SPIR 2.0? > > > > > > > > > > BTW, you also mentioned that it's possible to up modify your > > > > > implementation to align it with proposed version. > > > > > > > > > > > However, we can modify our implementation to adopt this change > > > > > > since it brings about benefits overall. > > > > > > > > > > Is it still an option? > > > > I was talking about SPIR in a general sense. What I said applies to > > > > either SPIR or SPIR-V, as long as we want a portable representation. > > > > Currently Clang does not support SPIR-V, but I guess the header file > > > > will be used for SPIR-V in the future in the similar way as it is used > > > > for SPIR. > > > > > > > > Yes, that is still an option. In that case I want a uniform > > > > compile-time constant definition for all targets. > > > > > > > > If we choose to allow each target having its own constant value, then > > > > for SPIR or SPIR-V it needs to be defined as a function. > > > > What I said applies to either SPIR or SPIR-V, as long as we want a > > > > portable representation. ... > > > > If we choose to allow each target having its own constant value, then > > > > for SPIR or SPIR-V it needs to be defined as a function. > > > > > > SPIR-V (as well as OpenCL) doesn't define CLK_NULL_RESERVE_ID, so it's > > > not portable. Replacing it with function call puts additional implicit > > > requirements for the frameworks consuming SPIR-V to provide > > > __clk_null_reserve_id function implementation. > > > > > > > Yes, that is still an option. In that case I want a uniform > > > > compile-time constant definition for all targets. > > > > > > So far, I'm in favor of this option. I think we need to bring this > > > question to the Khronos and either: > > > 1. define uniform compile-time constant > > > 2. make the OpenCL value implementation defined and introduce SPIR-V > > > representation for CLK_NULL_RESERVE_ID > > Agree. > I wish I understood why we have both CLK_NULL_RESERVE_ID and the function > is_valid_reserve_id(). We don't need both, and the predicate makes the code > clearer. Also, that macro implies that == and != must be defined for > reserve_id_t which is again undesirable. > > I'd say any CLK_* value is automatically implementation defined if its value > is not defined in the spec, but wouldn't object to clarifying with the > working group. Sorry, I didn't update this code review thread, but I emailed to the working group regarding whether this macro should be implementation defined or set by the spec, since we need some portable binary representation for SPIR-V format. This thread didn't received any attention, but I think I found the right SPIR-V representation for this particular case. @b-sumner brought another good question. It would be great if could resolve this ambiguity by removing CLK_NULL_RESERVE_ID macro. https://reviews.llvm.org/D32896 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
