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<font size="2"><span style="font-size:11pt">> Thanks for your explanation! My first impression is the implementation<br>
> is kind of OpenCL specific since there are lots of OpenCL term are<br>
> used in the implementa</span><span style="font-size: 11pt; font-family: calibri, arial, helvetica, sans-serif; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">tion including the option name used in tablegen,</span></font></div>
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<font size="2"><span style="font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">> but the mechnich seems could be generalized.</span></font></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Exactly, the names we used are OpenCL specific but the logic can</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">apply to C-based languages universally. You might find it easy to decode</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">if you look at the relevant spec part:</span></div>
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<a href="https://www.khronos.org/registry/OpenCL/specs/3.0-unified/html/OpenCL_C.html#built-in-functions" id="LPlnk"><span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">https://www.khronos.org/registry/OpenCL/specs/3.0-unified/html/OpenCL_C.html#built-in-functions</span></a></div>
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<font size="2"><span style="font-size:11pt">> Could you explain what the TableGen based header is ? Does it mean<br>
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<font size="2"><span style="font-size: 11pt; font-family: calibri, arial, helvetica, sans-serif; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">> OpenCLBuiltins.inc? or some other headers?</span></font><br>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Yes, this is a hook to Sema that is generated by the TableGen from</span></div>
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<code class="docutils literal notranslate"><span class="pre" style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">OpenCLBuiltins.td</span></code> description.<br>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">So if let's say we wanted to generalize the logic we would rename from</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">"OpenCLBuiltinStruct" -> "BuiltinStruct". Because this is just a data</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">structure that describes a function with its overloads.</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">I imagine the</span><span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">
only OpenCL-specific parts are Extensions and "gentype".</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">The concept of "gentype" is taken from</span></div>
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<a href="https://www.khronos.org/registry/OpenCL/specs/3.0-unified/html/OpenCL_C.html#math-functions" id="LPlnk961764"><span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">https://www.khronos.org/registry/OpenCL/specs/3.0-unified/html/OpenCL_C.html#math-functions</span></a></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">This is just a trick to make TableGen description and data structures much</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">smaller. I think it can be useful outside of OpenCL but only if there are</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">overloads with vector types for example.</span></div>
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> <font size="2"><span style="font-size:11pt">I guess we still needed for RISC-V since we don't want to import those<br>
symbols until include riscv_vector.h, but that should not conflict<br>
</span><span style="font-size: 11pt; font-family: calibri, arial, helvetica, sans-serif;">with the OpenCL built-in approach :)</span></font><br>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Indeed. In OpenCL language we don't have a way to activate/load the</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">builtins so they are always available. This is why we activate the Tablegen</span></div>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">header by a flag.</span><br>
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<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Chee</span><span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">rs,</span><br>
<span style="font-family: calibri, arial, helvetica, sans-serif; font-size: 11pt; color: rgb(0, 0, 0); background-color: rgba(0, 0, 0, 0);">Anastasia</span><br>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Kito Cheng <kito.cheng@gmail.com><br>
<b>Sent:</b> 23 June 2021 07:21<br>
<b>To:</b> Anastasia Stulova <Anastasia.Stulova@arm.com><br>
<b>Cc:</b> David Rector <davrecthreads@gmail.com>; Clang Dev <cfe-dev@lists.llvm.org>; Sven Van Haastregt <Sven.VanHaastregt@arm.com><br>
<b>Subject:</b> Re: [cfe-dev] [RFC][RISCV] Add intrinsic and/or builtin functions by #pragma</font>
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<div class="PlainText">Hi Anastasia:<br>
<br>
Thanks for your explanation! My first impression is the implementation<br>
is kind of OpenCL specific since there are lots of OpenCL term are<br>
used in the implementation including the option name used in tablegen,<br>
but the mechnich seems could be generalized.<br>
<br>
> We have removed the need for the pragmas in the last commits but it is mainly<br>
> because it wasn't useful in OpenCL in a way it was defined in the spec as it<br>
> was not similar to a header include. The TableGen based header include is very<br>
> fast compared to parsing the large header files so I can certainly recommend<br>
> this route.<br>
<br>
Could you explain what the TableGen based header is ? Does it mean<br>
OpenCLBuiltins.inc? or some other headers?<br>
<br>
I guess we still needed for RISC-V since we don't want to import those<br>
symbols until include riscv_vector.h, but that should not conflict<br>
with the OpenCL built-in approach :)<br>
<br>
Thanks!<br>
<br>
On Wed, Jun 23, 2021 at 1:50 AM Anastasia Stulova via cfe-dev<br>
<cfe-dev@lists.llvm.org> wrote:<br>
><br>
> FYI, in case it helps we have started documentation about the internals of the<br>
> approach <a href="https://clang.llvm.org/docs/OpenCLSupport.html#opencl-builtins">
https://clang.llvm.org/docs/OpenCLSupport.html#opencl-builtins</a>.<br>
> Although it is still a bit concise. There is not much OpenCL specific in the<br>
> approach we have implemented so it should be easily generalizable with some<br>
> renaming and minor refactoring (CC to Sven who might be able to provide more<br>
> info if needed). You might need to add a few special types if you use any that<br>
> we don't have in OpenCL yet. Although we have covered a good variety from C99<br>
> already.<br>
><br>
> We have removed the need for the pragmas in the last commits but it is mainly<br>
> because it wasn't useful in OpenCL in a way it was defined in the spec as it<br>
> was not similar to a header include. The TableGen based header include is very<br>
> fast compared to parsing the large header files so I can certainly recommend<br>
> this route.<br>
><br>
> Cheers,<br>
> Anastasia<br>
> ________________________________<br>
> From: cfe-dev <cfe-dev-bounces@lists.llvm.org> on behalf of Kito Cheng via cfe-dev <cfe-dev@lists.llvm.org><br>
> Sent: 22 June 2021 03:41<br>
> To: David Rector <davrecthreads@gmail.com><br>
> Cc: Clang Dev <cfe-dev@lists.llvm.org><br>
> Subject: Re: [cfe-dev] [RFC][RISCV] Add intrinsic and/or builtin functions by #pragma<br>
><br>
> Hi David:<br>
><br>
> Thanks for your info, I investigate OpenCL intrinsic last few days,<br>
> and I saw OpenCL already use some #pragama to control the extenison<br>
> on/off.<br>
> So I think the mechnish is pretty simiular, the difference is OpenCL<br>
> apporache need to write a new td file to generate those helper<br>
> functions.<br>
><br>
> And our apparoch is extending existing builtin declare mechnish: add<br>
> one filed to record the enable contdition.<br>
><br>
> We consider pre-compiled header before, but seems like pre-compiled<br>
> header are not fit RISC-V scenario - having different -march<br>
> combination which will affect the content of the header, so it seems<br>
> not work for RISC-V intrinsic headers.<br>
><br>
><br>
> Thanks :)<br>
><br>
> On Tue, Jun 15, 2021 at 11:11 PM David Rector via cfe-dev<br>
> <cfe-dev@lists.llvm.org> wrote:<br>
> ><br>
> > IIUC OpenCL faced the same issue, and their solution was pretty clever and generalizable; a similar approach could conceivably improve compile speeds still further, while also minimizing memory usage and making pragmas unnecessary.
<a href="https://lists.llvm.org/pipermail/cfe-dev/2021-February/067610.html">https://lists.llvm.org/pipermail/cfe-dev/2021-February/067610.html</a><br>
> ><br>
> > The basic idea if I recall (Anastasia cc’d might correct me), is to create the necessarily declarations whenever lookup fails. I.e., if lookup of `vint32m1_t` fails, before giving up clang checks if that is the name of one of your intrinsics; if so it
adds the necessarily declaration/overloaded declarations (the particulars handled via Tablegen) and returns that.<br>
> ><br>
> > The effect is to "instantiate" these declarations as needed, as if from a template.<br>
> ><br>
> > What also seems nice about this approach is that heavy-duty users can alternatively choose to just #include the large header, or use a pre-compiled header, and thereby automatically avoid any costs associated with this last-ditch-lookup solution.<br>
> ><br>
> > On Jun 15, 2021, at 2:59 AM, Kito Cheng via cfe-dev <cfe-dev@lists.llvm.org> wrote:<br>
> ><br>
> > Hi :<br>
> ><br>
> ><br>
> > # TL;DR:<br>
> ><br>
> > It's the intrinsic and/or builtin functions related issue again, in<br>
> > this RFC we are trying to use pragma to import intrinsics and declare<br>
> > intrinsic wrappers function to reduce the compilation time.<br>
> ><br>
> > And here is the PoC for this RFC:<br>
> > <a href="https://reviews.llvm.org/D103228">https://reviews.llvm.org/D103228</a><br>
> ><br>
> > # Background:<br>
> ><br>
> > RISC-V vector extension has defined 25,386 intrinsic and 2,102<br>
> > overloaded intrinsic functions in riscv_vector.h which increase a lot<br>
> > of compilation time; the header file contains ~60k lines for those<br>
> > overload functions and intrinsic wrapper functions.<br>
> ><br>
> > An empty file with include riscv_vector.h takes 0.395s on release<br>
> > build and 8.067s second on debug build, and this also increases the<br>
> > clang test time.<br>
> ><br>
> > # Proposal:<br>
> ><br>
> > Using Tablegen to generate the table of the intrinsic wrapper<br>
> > functions and then using pragma to declare intrinsic wrapper<br>
> > functions.<br>
> ><br>
> > Syntax:<br>
> > ```c<br>
> > #pragma riscv intrinsic vector<br>
> > ```<br>
> ><br>
> > Then import all builtin functions and intrinsic wrappers into the<br>
> > symbol table, this could save lots of time parsing the prototypes of<br>
> > the intrinsic wrapper function.<br>
> ><br>
> > And this idea of trick is borrowing from AArch64/SVE's implementation on GCC:<br>
> > <a href="https://github.com/gcc-mirror/gcc/blob/master/gcc/config/aarch64/arm_sve.h#L40">
https://github.com/gcc-mirror/gcc/blob/master/gcc/config/aarch64/arm_sve.h#L40</a><br>
> ><br>
> ><br>
> > # Experimental Results:<br>
> > ## Size of riscv_vector.h:<br>
> > | size | LoC |<br>
> > ------------------------------<br>
> > Before | 4,434,725 | 69,749 |<br>
> > After | 5,463 | 159 |<br>
> ><br>
> > ## Compilation Speed for Simple File<br>
> ><br>
> > testcase:<br>
> > ```c<br>
> > #include <riscv_vector.h><br>
> ><br>
> > vint32m1_t test_vadd_vv_vfloat32m1_t(vint32m1_t op1, vint32m1_t op2,<br>
> > size_t vl) {<br>
> > return vadd(op1, op2, vl);<br>
> > }<br>
> > ```<br>
> ><br>
> > Release build:<br>
> > Before: 0m0.417s<br>
> > After: 0m0.090s<br>
> ><br>
> > Debug build:<br>
> > Before: 0m8.016s<br>
> > After: 0m2.295s<br>
> ><br>
> ><br>
> > ## Regression Time<br>
> > LLVM regression on our 48 core server:<br>
> > Release build:<br>
> > Before : Testing Time: 203.81s<br>
> > After : Testing Time: 181.13s<br>
> ><br>
> > Debug build:<br>
> > Before : Testing Time: 675.18s<br>
> > After : Testing Time: 647.20s<br>
> ><br>
> ><br>
> ><br>
> > Any comments or feedback are appreciated!<br>
> > _______________________________________________<br>
> > cfe-dev mailing list<br>
> > cfe-dev@lists.llvm.org<br>
> > <a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a><br>
> ><br>
> ><br>
> > _______________________________________________<br>
> > cfe-dev mailing list<br>
> > cfe-dev@lists.llvm.org<br>
> > <a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a><br>
> _______________________________________________<br>
> cfe-dev mailing list<br>
> cfe-dev@lists.llvm.org<br>
> <a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a><br>
> _______________________________________________<br>
> cfe-dev mailing list<br>
> cfe-dev@lists.llvm.org<br>
> <a href="https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev">https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-dev</a><br>
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