Add feature flag for relaxed atomics

Author: stevenfontanella

src/binaryen-c.cpp

@@ -487,6 +487,9 @@ BinaryenFeatures BinaryenFeatureBulkMemoryOpt(void) {
 BinaryenFeatures BinaryenFeatureCallIndirectOverlong(void) {
   return static_cast<BinaryenFeatures>(FeatureSet::CallIndirectOverlong);
 }
+BinaryenFeatures BinaryenFeatureRelaxedAtomics(void) {
+  return static_cast<BinaryenFeatures>(FeatureSet::RelaxedAtomics);
+}
 BinaryenFeatures BinaryenFeatureAll(void) {
   return static_cast<BinaryenFeatures>(FeatureSet::All);
 }

src/binaryen-c.h

@@ -230,6 +230,7 @@ BINARYEN_API BinaryenFeatures BinaryenFeatureSharedEverything(void);
 BINARYEN_API BinaryenFeatures BinaryenFeatureFP16(void);
 BINARYEN_API BinaryenFeatures BinaryenFeatureBulkMemoryOpt(void);
 BINARYEN_API BinaryenFeatures BinaryenFeatureCallIndirectOverlong(void);
+BINARYEN_API BinaryenFeatures BinaryenFeatureRelaxedAtomics(void);
 BINARYEN_API BinaryenFeatures BinaryenFeatureAll(void);
 
 // Modules

src/tools/tool-options.h

@@ -108,6 +108,8 @@ struct ToolOptions : public Options {
       .addFeature(FeatureSet::FP16, "float 16 operations")
       .addFeature(FeatureSet::CustomDescriptors,
                   "custom descriptors (RTTs) and exact references")
+      .addFeature(FeatureSet::RelaxedAtomics,
+                  "acquire/release atomic memory operations")
       .add("--enable-typed-function-references",
            "",
            "Deprecated compatibility flag",

src/wasm-binary.h

@@ -460,6 +460,7 @@ extern const char* FP16Feature;
 extern const char* BulkMemoryOptFeature;
 extern const char* CallIndirectOverlongFeature;
 extern const char* CustomDescriptorsFeature;
+extern const char* RelaxedAtomicsFeature;
 
 enum Subsection {
   NameModule = 0,

src/wasm-features.h

@@ -55,11 +55,12 @@ struct FeatureSet {
     // it does nothing. Binaryen always accepts LEB call-indirect encodings.
     CallIndirectOverlong = 1 << 20,
     CustomDescriptors = 1 << 21,
+    RelaxedAtomics = 1 << 22,
     MVP = None,
     // Keep in sync with llvm default features:
     // https://github.com/llvm/llvm-project/blob/c7576cb89d6c95f03968076e902d3adfd1996577/clang/lib/Basic/Targets/WebAssembly.cpp#L150-L153
     Default = SignExt | MutableGlobals,
-    All = (1 << 22) - 1,
+    All = (1 << 23) - 1,
   };
 
   static std::string toString(Feature f) {
@@ -108,6 +109,8 @@ struct FeatureSet {
         return "call-indirect-overlong";
       case CustomDescriptors:
         return "custom-descriptors";
+      case RelaxedAtomics:
+        return "relaxed-atomics";
       case MVP:
       case Default:
       case All:
@@ -168,6 +171,7 @@ struct FeatureSet {
   bool hasCustomDescriptors() const {
     return (features & CustomDescriptors) != 0;
   }
+  bool hasRelaxedAtomics() const { return (features & RelaxedAtomics) != 0; }
   bool hasAll() const { return (features & All) != 0; }
 
   void set(FeatureSet f, bool v = true) {
@@ -194,6 +198,7 @@ struct FeatureSet {
   void setFP16(bool v = true) { set(FP16, v); }
   void setBulkMemoryOpt(bool v = true) { set(BulkMemoryOpt, v); }
   void setCustomDescriptors(bool v = true) { set(CustomDescriptors, v); }
+  void setRelaxedAtomics(bool v = true) { set(RelaxedAtomics, v); }
   void setMVP() { features = MVP; }
   void setAll() { features = All; }
 

src/wasm/wasm-binary.cpp

@@ -1441,6 +1441,8 @@ void WasmBinaryWriter::writeFeaturesSection() {
         return BinaryConsts::CustomSections::CallIndirectOverlongFeature;
       case FeatureSet::CustomDescriptors:
         return BinaryConsts::CustomSections::CustomDescriptorsFeature;
+      case FeatureSet::RelaxedAtomics:
+        return BinaryConsts::CustomSections::RelaxedAtomicsFeature;
       case FeatureSet::None:
       case FeatureSet::Default:
       case FeatureSet::All:
@@ -5296,6 +5298,8 @@ void WasmBinaryReader::readFeatures(size_t sectionPos, size_t payloadLen) {
       feature = FeatureSet::FP16;
     } else if (name == BinaryConsts::CustomSections::CustomDescriptorsFeature) {
       feature = FeatureSet::CustomDescriptors;
+    } else if (name == BinaryConsts::CustomSections::RelaxedAtomicsFeature) {
+      feature = FeatureSet::RelaxedAtomics;
     } else {
       // Silently ignore unknown features (this may be and old binaryen running
       // on a new wasm).

src/wasm/wasm-validator.cpp

@@ -1108,6 +1108,12 @@ void FunctionValidator::visitLoad(Load* curr) {
                  curr,
                  "Atomic load should be i32 or i64");
   }
+  if (curr->order == MemoryOrder::AcqRel) {
+    shouldBeTrue(getModule()->features.hasRelaxedAtomics(),
+                 curr,
+                 "Acquire/release operations require relaxed atomics "
+                 "[--enable-relaxed-atomics]");
+  }
   if (curr->type == Type::v128) {
     shouldBeTrue(getModule()->features.hasSIMD(),
                  curr,

src/wasm/wasm.cpp

@@ -61,6 +61,7 @@ const char* FP16Feature = "fp16";
 const char* BulkMemoryOptFeature = "bulk-memory-opt";
 const char* CallIndirectOverlongFeature = "call-indirect-overlong";
 const char* CustomDescriptorsFeature = "custom-descriptors";
+const char* RelaxedAtomicsFeature = "relaxed-atomics";
 
 } // namespace BinaryConsts::CustomSections
 

test/binaryen.js/kitchen-sink.js

@@ -100,6 +100,7 @@ function test_features() {
   console.log("Features.ExtendedConst: " + binaryen.Features.ExtendedConst);
   console.log("Features.Strings: " + binaryen.Features.Strings);
   console.log("Features.MultiMemory: " + binaryen.Features.MultiMemory);
+  console.log("Features.RelaxedAtomics: " + binaryen.Features.RelaxedAtomics);
   console.log("Features.All: " + binaryen.Features.All);
 }
 

test/binaryen.js/kitchen-sink.js.txt

@@ -33,7 +33,8 @@ Features.RelaxedSIMD: 4096
 Features.ExtendedConst: 8192
 Features.Strings: 16384
 Features.MultiMemory: 32768
-Features.All: 4194303
+Features.RelaxedAtomics: 4194304
+Features.All: 8388607
 InvalidId: 0
 BlockId: 1
 IfId: 2