[WebAssembly] Add new target feature in support of 'extended-const' proposal

[sbc100]

Summary

We don't yet do anything when this feature is enabled, this change
just lays the ground work by accepting that there is such a feature.

See https://github.com/WebAssembly/extended-const

[sbc100]

Surprising amount of boilerplate here..

clang/docs/ClangCommandLineReference.rst

 .. option:: -mrelaxed-simd, -mno-relaxed-simd
 
 .. option:: -msign-ext, -mno-sign-ext
 
 .. option:: -msimd128, -mno-simd128
 
 .. option:: -mtail-call, -mno-tail-call
 
+.. option:: -mextended-const, -mno-extended-const
+
 WebAssembly Driver
 ------------------
 .. option:: -mexec-model=<arg>
 
 Execution model (WebAssembly only)
 
 X86
 ---

clang/include/clang/Driver/Options.td

 def mmutable_globals : Flag<["-"], "mmutable-globals">, Group<m_wasm_Features_Group>;
 def mno_mutable_globals : Flag<["-"], "mno-mutable-globals">, Group<m_wasm_Features_Group>;
 def mmultivalue : Flag<["-"], "mmultivalue">, Group<m_wasm_Features_Group>;
 def mno_multivalue : Flag<["-"], "mno-multivalue">, Group<m_wasm_Features_Group>;
 def mtail_call : Flag<["-"], "mtail-call">, Group<m_wasm_Features_Group>;
 def mno_tail_call : Flag<["-"], "mno-tail-call">, Group<m_wasm_Features_Group>;
 def mreference_types : Flag<["-"], "mreference-types">, Group<m_wasm_Features_Group>;
 def mno_reference_types : Flag<["-"], "mno-reference-types">, Group<m_wasm_Features_Group>;
+def mextended_const : Flag<["-"], "mextended-const">, Group<m_wasm_Features_Group>;
+def mno_extended_const : Flag<["-"], "mno-extended-const">, Group<m_wasm_Features_Group>;
 def mexec_model_EQ : Joined<["-"], "mexec-model=">, Group<m_wasm_Features_Driver_Group>,
                      Values<"command,reactor">,
                      HelpText<"Execution model (WebAssembly only)">;
 
 defm amdgpu_ieee : BoolOption<"m", "amdgpu-ieee",
   CodeGenOpts<"EmitIEEENaNCompliantInsts">, DefaultTrue,
   PosFlag<SetTrue, [], "Sets the IEEE bit in the expected default floating point "
   " mode register. Floating point opcodes that support exception flag "

clang/lib/Basic/Targets/WebAssembly.h

class LLVM_LIBRARY_VISIBILITY WebAssemblyTargetInfo : public TargetInfo {
   bool HasSignExt = false;
   bool HasExceptionHandling = false;
   bool HasBulkMemory = false;
   bool HasAtomics = false;
   bool HasMutableGlobals = false;
   bool HasMultivalue = false;
   bool HasTailCall = false;
   bool HasReferenceTypes = false;
+  bool HasExtendedConst = false;
 
   std::string ABI;
 
 public:
   explicit WebAssemblyTargetInfo(const llvm::Triple &T, const TargetOptions &)
       : TargetInfo(T) {
     NoAsmVariants = true;
     SuitableAlign = 128;

clang/lib/Basic/Targets/WebAssembly.cpp

return llvm::StringSwitch<bool>(Feature)
       .Case("sign-ext", HasSignExt)
       .Case("exception-handling", HasExceptionHandling)
       .Case("bulk-memory", HasBulkMemory)
       .Case("atomics", HasAtomics)
       .Case("mutable-globals", HasMutableGlobals)
       .Case("multivalue", HasMultivalue)
       .Case("tail-call", HasTailCall)
       .Case("reference-types", HasReferenceTypes)
+      .Case("extended-const", HasExtendedConst)
       .Default(false);
 }
 
 bool WebAssemblyTargetInfo::isValidCPUName(StringRef Name) const {
   return llvm::is_contained(ValidCPUNames, Name);
 }
 
 void WebAssemblyTargetInfo::fillValidCPUList(
void WebAssemblyTargetInfo::getTargetDefines(const LangOptions &Opts,
   if (HasMutableGlobals)
     Builder.defineMacro("__wasm_mutable_globals__");
   if (HasMultivalue)
     Builder.defineMacro("__wasm_multivalue__");
   if (HasTailCall)
     Builder.defineMacro("__wasm_tail_call__");
   if (HasReferenceTypes)
     Builder.defineMacro("__wasm_reference_types__");
+  if (HasExtendedConst)
+    Builder.defineMacro("__wasm_extended_const__");
 }
 
 void WebAssemblyTargetInfo::setSIMDLevel(llvm::StringMap<bool> &Features,
                                          SIMDEnum Level, bool Enabled) {
   if (Enabled) {
     switch (Level) {
     case RelaxedSIMD:
       Features["relaxed-simd"] = true;
for (const auto &Feature : Features) {
     if (Feature == "+reference-types") {
       HasReferenceTypes = true;
       continue;
     }
     if (Feature == "-reference-types") {
       HasReferenceTypes = false;
       continue;
     }
+    if (Feature == "+extended-const") {
+      HasExtendedConst = true;
+      continue;
+    }
+    if (Feature == "-extended-const") {
+      HasExtendedConst = false;
+      continue;
+    }
 
     Diags.Report(diag::err_opt_not_valid_with_opt)
         << Feature << "-target-feature";
     return false;
   }
   return true;
 }
 

clang/test/Preprocessor/wasm-target-features.c

 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mreference-types \
 // RUN:   | FileCheck %s -check-prefix=REFERENCE-TYPES
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm64-unknown-unknown -mreference-types \
 // RUN:   | FileCheck %s -check-prefix=REFERENCE-TYPES
 //
 // REFERENCE-TYPES:#define __wasm_reference_types__ 1{{$}}
+//
+// RUN: %clang -E -dM %s -o - 2>&1 \
+// RUN:     -target wasm32-unknown-unknown -mextended-const \
+// RUN:   | FileCheck %s -check-prefix=EXTENDED-CONST
+// RUN: %clang -E -dM %s -o - 2>&1 \
+// RUN:     -target wasm64-unknown-unknown -mextended-const \
+// RUN:   | FileCheck %s -check-prefix=EXTENDED-CONST
+//
+// EXTENDED-CONST:#define __wasm_extended_const__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=mvp \
 // RUN:   | FileCheck %s -check-prefix=MVP
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm64-unknown-unknown -mcpu=mvp \
 // RUN:   | FileCheck %s -check-prefix=MVP
 //
 // MVP-NOT:#define __wasm_simd128__
 // MVP-NOT:#define __wasm_nontrapping_fptoint__
 // MVP-NOT:#define __wasm_sign_ext__
 // MVP-NOT:#define __wasm_exception_handling__
 // MVP-NOT:#define __wasm_bulk_memory__
 // MVP-NOT:#define __wasm_atomics__
 // MVP-NOT:#define __wasm_mutable_globals__
 // MVP-NOT:#define __wasm_multivalue__
 // MVP-NOT:#define __wasm_tail_call__
 // MVP-NOT:#define __wasm_reference_types__
+// MVP-NOT:#define __wasm_extended_const__
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=bleeding-edge \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm64-unknown-unknown -mcpu=bleeding-edge \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE
 //
 // BLEEDING-EDGE-DAG:#define __wasm_nontrapping_fptoint__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_sign_ext__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_bulk_memory__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_simd128__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_atomics__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_mutable_globals__ 1{{$}}
 // BLEEDING-EDGE-DAG:#define __wasm_tail_call__ 1{{$}}
 // BLEEDING-EDGE-NOT:#define __wasm_unimplemented_simd128__ 1{{$}}
 // BLEEDING-EDGE-NOT:#define __wasm_exception_handling__ 1{{$}}
 // BLEEDING-EDGE-NOT:#define __wasm_multivalue__ 1{{$}}
 // BLEEDING-EDGE-NOT:#define __wasm_reference_types__ 1{{$}}
+// BLEEDING-EDGE-NOT:#define __wasm_extended_const__ 1{{$}}
 
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm32-unknown-unknown -mcpu=bleeding-edge -mno-simd128 \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE-NO-SIMD128
 // RUN: %clang -E -dM %s -o - 2>&1 \
 // RUN:     -target wasm64-unknown-unknown -mcpu=bleeding-edge -mno-simd128 \
 // RUN:   | FileCheck %s -check-prefix=BLEEDING-EDGE-NO-SIMD128
 //
 // BLEEDING-EDGE-NO-SIMD128-NOT:#define __wasm_simd128__

llvm/lib/Target/WebAssembly/WebAssembly.td

 def FeatureMutableGlobals :
       SubtargetFeature<"mutable-globals", "HasMutableGlobals", "true",
                        "Enable mutable globals">;
 
 def FeatureReferenceTypes :
       SubtargetFeature<"reference-types", "HasReferenceTypes", "true",
                        "Enable reference types">;
 
+def FeatureExtendedConst :
+      SubtargetFeature<"extended-const", "HasExtendedConst", "true",
+                       "Enable extended const expressions">;
+
 //===----------------------------------------------------------------------===//
 // Architectures.
 //===----------------------------------------------------------------------===//
 
 //===----------------------------------------------------------------------===//
 // Register File Description
 //===----------------------------------------------------------------------===//
 

llvm/lib/Target/WebAssembly/WebAssemblyInstrInfo.td

 def HasBulkMemory :
     Predicate<"Subtarget->hasBulkMemory()">,
     AssemblerPredicate<(all_of FeatureBulkMemory), "bulk-memory">;
 
 def HasReferenceTypes :
     Predicate<"Subtarget->hasReferenceTypes()">,
     AssemblerPredicate<(all_of FeatureReferenceTypes), "reference-types">;
 
+def HasExtendedConst :
+    Predicate<"Subtarget->hasExtendedConst()">,
+    AssemblerPredicate<(all_of FeatureExtendedConst), "extended-const">;
+
 //===----------------------------------------------------------------------===//
 // WebAssembly-specific DAG Node Types.
 //===----------------------------------------------------------------------===//
 
 def SDT_WebAssemblyCallSeqStart : SDCallSeqStart<[SDTCisVT<0, iPTR>,
                                                   SDTCisVT<1, iPTR>]>;
 def SDT_WebAssemblyCallSeqEnd :
     SDCallSeqEnd<[SDTCisVT<0, iPTR>, SDTCisVT<1, iPTR>]>;

llvm/lib/Target/WebAssembly/WebAssemblySubtarget.h

class WebAssemblySubtarget final : public WebAssemblyGenSubtargetInfo {
   bool HasNontrappingFPToInt = false;
   bool HasSignExt = false;
   bool HasExceptionHandling = false;
   bool HasBulkMemory = false;
   bool HasMultivalue = false;
   bool HasMutableGlobals = false;
   bool HasTailCall = false;
   bool HasReferenceTypes = false;
+  bool HasExtendedConst = false;
 
   /// What processor and OS we're targeting.
   Triple TargetTriple;
 
   WebAssemblyFrameLowering FrameLowering;
   WebAssemblyInstrInfo InstrInfo;
   WebAssemblySelectionDAGInfo TSInfo;
   WebAssemblyTargetLowering TLInfo;