[OpenCL] Change OpenCL builtin version encoding

[svenvh]

Summary

Instead of using a MinVersion and MaxVersion field, encode the version
of a builtin using a mask that aligns better with version handling in
OpenCLOptions.h. In addition, this saves a field in the BuiltinTable.

This change allows a finer-grained control over the OpenCL versions in
which a builtin is available: instead of a range, we can now toggle
each version individually.

The fine-grained version control is not yet exposed on the TableGen
definitions side, as changes for OpenCL 3 feature optionality still
need to be defined and will affect how we want to expose these.

[azabaznov]

Great! And thanks for fixing misprint :)

clang/utils/TableGen/ClangOpenCLBuiltinEmitter.cpp

507

nit: Encoded |= clang::encodeOpenCLVersion(VersionIDs[I]);

[svenvh]

clang/utils/TableGen/ClangOpenCLBuiltinEmitter.cpp

507

I wish I could use encodeOpenCLVersion indeed, but the Clang headers are not available in TableGen (see comment on line 493). I couldn't think of a better solution unfortunately, but let me know if you have any suggestions.

[azabaznov]

clang/utils/TableGen/ClangOpenCLBuiltinEmitter.cpp

507

Oh, got it! I see no solution except conceptually changing this: allow including clang headers in TableGen util. Seems like it's not possible yet. I think we can go ahead with your solution for now.

[srj]

This change appears to be the injection point for https://bugs.llvm.org/show_bug.cgi?id=50128 -- trying to build clang-tblgen after this change crashes VC2019 if targeting 32-bit Windows (see below). While this is likely an MSVC bug, I presume we still want to support crosscompiling for 32-bit Windows?

[2220/3953] Building CXX object tools\clang\utils\TableGen\CMakeFiles\clang-tblgen.dir\ClangOpenCLBuiltinEmitter.cpp.obj
FAILED: tools/clang/utils/TableGen/CMakeFiles/clang-tblgen.dir/ClangOpenCLBuiltinEmitter.cpp.obj 
C:\PROGRA~2\MICROS~2\2019\COMMUN~1\VC\Tools\MSVC\1428~1.293\bin\Hostx64\x86\cl.exe  /nologo /TP -DCLANG_ROUND_TRIP_CC1_ARGS=ON -DUNICODE -D_CRT_NONSTDC_NO_DEPRECATE -D_CRT_NONSTDC_NO_WARNINGS -D_CRT_SECURE_NO_DEPRECATE -D_CRT_SECURE_NO_WARNINGS -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -D_HAS_EXCEPTIONS=0 -D_LARGEFILE_SOURCE -D_SCL_SECURE_NO_DEPRECATE -D_SCL_SECURE_NO_WARNINGS -D_UNICODE -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -D__STDC_LIMIT_MACROS -Itools\clang\utils\TableGen -IC:\code\build_bot\worker\llvm-13-x86-32-windows\llvm-project\clang\utils\TableGen -IC:\code\build_bot\worker\llvm-13-x86-32-windows\llvm-project\clang\include -Itools\clang\include -Iinclude -IC:\code\build_bot\worker\llvm-13-x86-32-windows\llvm-project\llvm\include /DWIN32 /D_WINDOWS   /Zc:inline /Zc:__cplusplus /Zc:strictStrings /Oi /Zc:rvalueCast /bigobj /W4 -wd4141 -wd4146 -wd4244 -wd4267 -wd4291 -wd4351 -wd4456 -wd4457 -wd4458 -wd4459 -wd4503 -wd4624 -wd4722 -wd4100 -wd4127 -wd4512 -wd4505 -wd4610 -wd4510 -wd4702 -wd4245 -wd4706 -wd4310 -wd4701 -wd4703 -wd4389 -wd4611 -wd4805 -wd4204 -wd4577 -wd4091 -wd4592 -wd4319 -wd4709 -wd4324 -w14062 -we4238 /Gw /MD /O2 /Ob2  /EHs-c- /GR -UNDEBUG -std:c++14 /showIncludes /Fotools\clang\utils\TableGen\CMakeFiles\clang-tblgen.dir\ClangOpenCLBuiltinEmitter.cpp.obj /Fdtools\clang\utils\TableGen\CMakeFiles\clang-tblgen.dir\ /FS -c C:\code\build_bot\worker\llvm-13-x86-32-windows\llvm-project\clang\utils\TableGen\ClangOpenCLBuiltinEmitter.cpp
C:\code\build_bot\worker\llvm-13-x86-32-windows\llvm-project\clang\utils\TableGen\ClangOpenCLBuiltinEmitter.cpp(514) : fatal error C1001: Internal compiler error.
(compiler file 'd:\A01\_work\3\s\src\vctools\Compiler\Utc\src\p2\main.c', line 212)
 To work around this problem, try simplifying or changing the program near the locations listed above.
If possible please provide a repro here: https://developercommunity.visualstudio.com 
Please choose the Technical Support command on the Visual C++ 
 Help menu, or open the Technical Support help file for more information
  cl!RaiseException()+0x69
  cl!RaiseException()+0x69
  cl!CloseTypeServerPDB()+0x22ebf
  cl!CloseTypeServerPDB()+0xedea9

[svenvh]

In D100492#2717232, @srj wrote:

This change appears to be the injection point for https://bugs.llvm.org/show_bug.cgi?id=50128 -- trying to build clang-tblgen after this change crashes VC2019 if targeting 32-bit Windows (see below). While this is likely an MSVC bug, I presume we still want to support crosscompiling for 32-bit Windows?

I am happy to make/accept any adjustments to this patch to fix the particular build. I don't have access to MSVC though, would you be able to help figure out what the problematic construct in my patch was?

[srj]

From experimentation, it appears that just pulling the MinVersion and MaxVersion expressions from BuiltinNameEmitter::EmitBuiltinTable into separate statements will pacify MSVC, e.g.

auto MinVersion = Overload.first->getValueAsDef("MinVersion")->getValueAsInt("ID");
auto MaxVersion = Overload.first->getValueAsDef("MaxVersion")->getValueAsInt("ID");
OS << "  { " << Overload.second << ", "
   << Overload.first->getValueAsListOfDefs("Signature").size() << ", "
   << (Overload.first->getValueAsBit("IsPure")) << ", "
   << (Overload.first->getValueAsBit("IsConst")) << ", "
   << (Overload.first->getValueAsBit("IsConv")) << ", "
   << FunctionExtensionIndex[ExtName] << ", "
   << MinVersion 
   << ", "
   << MaxVersion 
   << " },\n";

[srj]

(This is clearly just a weird bug on MSVC's part; there's nothing about the code here that seems obviously unreasonable or complex. Working around compiler bugs is a thing, alas.)

[srj]

In D100492#2717235, @svenvh wrote:

I am happy to make/accept any adjustments to this patch to fix the particular build. I don't have access to MSVC though, would you be able to help figure out what the problematic construct in my patch was?

See my comment above with minor code shuffling which seems to satisfy the compiler.

[svenvh]

Thanks for experimenting! I have pushed 37bc1dc9877f ("[NFC] Workaround MSVC2019 32-bit compiler crash", 2021-04-27).

clang/lib/Sema/SemaLookup.cpp

static void InsertOCLBuiltinDeclarationsFromTable(Sema &S, LookupResult &LR,
                                                   const unsigned Len) {
   // The builtin function declaration uses generic types (gentype).
   bool HasGenType = false;
 
   // Maximum number of types contained in a generic type used as return type or
   // as argument.  Only meaningful for generic types, otherwise equals 1.
   unsigned GenTypeMaxCnt;
 
+  ASTContext &Context = S.Context;
+
   for (unsigned SignatureIndex = 0; SignatureIndex < Len; SignatureIndex++) {
     const OpenCLBuiltinStruct &OpenCLBuiltin =
         BuiltinTable[FctIndex + SignatureIndex];
-    ASTContext &Context = S.Context;
 
-    // Ignore this BIF if its version does not match the language options.
-    unsigned OpenCLVersion = Context.getLangOpts().OpenCLVersion;
-    if (Context.getLangOpts().OpenCLCPlusPlus)
-      OpenCLVersion = 200;
-    if (OpenCLVersion < OpenCLBuiltin.MinVersion)
-      continue;
-    if ((OpenCLBuiltin.MaxVersion != 0) &&
-        (OpenCLVersion >= OpenCLBuiltin.MaxVersion))
+    // Ignore this builtin function if it is not available in the currently
+    // selected language version.
+    if (!isOpenCLVersionContainedInMask(Context.getLangOpts(),
+                                        OpenCLBuiltin.Versions))
       continue;
 
     // Ignore this builtin function if it carries an extension macro that is
     // not defined. This indicates that the extension is not supported by the
     // target, so the builtin function should not be available.
     StringRef Extensions = FunctionExtensionTable[OpenCLBuiltin.Extension];
     if (!Extensions.empty()) {
       SmallVector<StringRef, 2> ExtVec;

clang/utils/TableGen/ClangOpenCLBuiltinEmitter.cpp

struct OpenCLBuiltinStruct {
   // Function attribute __attribute__((pure))
   const bool IsPure : 1;
   // Function attribute __attribute__((const))
   const bool IsConst : 1;
   // Function attribute __attribute__((convergent))
   const bool IsConv : 1;
   // OpenCL extension(s) required for this overload.
   const unsigned short Extension;
-  // First OpenCL version in which this overload was introduced (e.g. CL20).
-  const unsigned short MinVersion;
-  // First OpenCL version in which this overload was removed (e.g. CL20).
-  const unsigned short MaxVersion;
+  // OpenCL versions in which this overload is available.
+  const unsigned short Versions;
 };
 
 )";
 }
 
 // Verify that the combination of GenTypes in a signature is supported.
 // To simplify the logic for creating overloads in SemaLookup, only allow
 // a signature to contain different GenTypes if these GenTypes represent
for (const Record *R : P.first) {
       }
       OS << Entry << ", ";
     }
     OS << "\n";
   }
   OS << "};\n\n";
 }
 
+// Encode a range MinVersion..MaxVersion into a single bit mask that can be
+// checked against LangOpts using isOpenCLVersionContainedInMask().
+// This must be kept in sync with OpenCLVersionID in OpenCLOptions.h.
+// (Including OpenCLOptions.h here would be a layering violation.)
+static unsigned short EncodeVersions(unsigned int MinVersion,
+                                     unsigned int MaxVersion) {
+  unsigned short Encoded = 0;
+
+  // A maximum version of 0 means available in all later versions.
+  if (MaxVersion == 0) {
+    MaxVersion = UINT_MAX;
+  }
+
+  unsigned VersionIDs[] = {100, 110, 120, 200, 300};
+  for (unsigned I = 0; I < sizeof(VersionIDs) / sizeof(VersionIDs[0]); I++) {
+    if (VersionIDs[I] >= MinVersion && VersionIDs[I] < MaxVersion) {
+      Encoded |= 1 << I;
+    }
+  }
+
+  return Encoded;
+}
+
 void BuiltinNameEmitter::EmitBuiltinTable() {
   unsigned Index = 0;
 
   OS << "static const OpenCLBuiltinStruct BuiltinTable[] = {\n";
   for (const auto &SLM : SignatureListMap) {
 
     OS << "  // " << (Index + 1) << ": ";
     for (const auto &Name : SLM.second.Names) {
       OS << Name << ", ";
     }
     OS << "\n";
 
     for (const auto &Overload : SLM.second.Signatures) {
       StringRef ExtName = Overload.first->getValueAsDef("Extension")->getName();
       OS << "  { " << Overload.second << ", "
          << Overload.first->getValueAsListOfDefs("Signature").size() << ", "
          << (Overload.first->getValueAsBit("IsPure")) << ", "
          << (Overload.first->getValueAsBit("IsConst")) << ", "
          << (Overload.first->getValueAsBit("IsConv")) << ", "
          << FunctionExtensionIndex[ExtName] << ", "
-         << Overload.first->getValueAsDef("MinVersion")->getValueAsInt("ID")
-         << ", "
-         << Overload.first->getValueAsDef("MaxVersion")->getValueAsInt("ID")
+         << EncodeVersions(Overload.first->getValueAsDef("MinVersion")
+                               ->getValueAsInt("ID"),
+                           Overload.first->getValueAsDef("MaxVersion")
+                               ->getValueAsInt("ID"))
          << " },\n";
       Index++;
     }
   }
   OS << "};\n\n";
 }
 
 bool BuiltinNameEmitter::CanReuseSignature(