Add support for LLVM import_module annotation

Used for defining wasm import module for a fun binding

Author: maxfierke

src/compiler/crystal/codegen/ast.cr

@@ -35,6 +35,10 @@ module Crystal
   class Def
     property? abi_info = false
 
+    def import_module
+      nil
+    end
+
     def mangled_name(program, self_type)
       name = String.build do |str|
         str << '*'

src/compiler/crystal/codegen/fun.cr

@@ -357,6 +357,12 @@ class Crystal::CodeGenVisitor
       context.fun.call_convention = call_convention
     end
 
+    if @program.has_flag?("wasi")
+      if import_module = target_def.import_module
+        context.fun.add_target_dependent_attribute("wasm-import-module", import_module)
+      end
+    end
+
     i = 0
     args.each do |arg|
       param = context.fun.params[i + offset]

src/compiler/crystal/program.cr

@@ -219,6 +219,7 @@ module Crystal
       # Built-in annotations
       types["AlwaysInline"] = @always_inline_annotation = AnnotationType.new self, self, "AlwaysInline"
       types["CallConvention"] = @call_convention_annotation = AnnotationType.new self, self, "CallConvention"
+      types["ImportModule"] = @import_module_annotation = AnnotationType.new self, self, "ImportModule"
       types["Extern"] = @extern_annotation = AnnotationType.new self, self, "Extern"
       types["Flags"] = @flags_annotation = AnnotationType.new self, self, "Flags"
       types["Link"] = @link_annotation = AnnotationType.new self, self, "Link"
@@ -447,7 +448,7 @@ module Crystal
                      exception tuple named_tuple proc union enum range regex crystal
                      packed_annotation thread_local_annotation no_inline_annotation
                      always_inline_annotation naked_annotation returns_twice_annotation
-                     raises_annotation primitive_annotation call_convention_annotation
+                     raises_annotation primitive_annotation call_convention_annotation import_module_annotation
                      flags_annotation link_annotation extern_annotation deprecated_annotation experimental_annotation) %}
       def {{name.id}}
         @{{name.id}}.not_nil!

src/compiler/crystal/semantic/ast.cr

@@ -623,6 +623,7 @@ module Crystal
     property real_name : String
     property! fun_def : FunDef
     property call_convention : LLVM::CallConvention?
+    property import_module : String?
 
     property? dead = false
     property? used = false

src/compiler/crystal/semantic/top_level_visitor.cr

@@ -477,6 +477,8 @@ class Crystal::TopLevelVisitor < Crystal::SemanticVisitor
         type.add_link_annotation(link_annotation)
       when @program.call_convention_annotation
         type.call_convention = parse_call_convention(ann, type.call_convention)
+      when @program.import_module_annotation
+        type.import_module = parse_import_module(ann, type.import_module)
       else
         # not a built-in annotation
       end
@@ -860,11 +862,15 @@ class Crystal::TopLevelVisitor < Crystal::SemanticVisitor
     external = External.new(node.name, ([] of Arg), node.body, node.real_name).at(node)
 
     call_convention = nil
+    import_module = nil
+
     process_def_annotations(external, annotations) do |annotation_type, ann|
       if annotation_type == @program.call_convention_annotation
         call_convention = parse_call_convention(ann, call_convention)
+      elsif annotation_type == @program.import_module_annotation
+        import_module = parse_import_module(ann, import_module)
       else
-        ann.raise "funs can only be annotated with: NoInline, AlwaysInline, Naked, ReturnsTwice, Raises, CallConvention"
+        ann.raise "funs can only be annotated with: NoInline, AlwaysInline, Naked, ReturnsTwice, Raises, CallConvention, ImportModule"
       end
     end
 
@@ -877,9 +883,14 @@ class Crystal::TopLevelVisitor < Crystal::SemanticVisitor
       call_convention = scope.call_convention
     end
 
+    if !call_convention && scope.is_a?(LibType)
+      import_module = scope.import_module
+    end
+
     # We fill the arguments and return type in TypeDeclarationVisitor
     external.doc = node.doc
     external.call_convention = call_convention
+    external.import_module = import_module
     external.varargs = node.varargs?
     external.fun_def = node
     node.external = external
@@ -1055,6 +1066,27 @@ class Crystal::TopLevelVisitor < Crystal::SemanticVisitor
     call_convention
   end
 
+  def parse_import_module(ann, import_module)
+    if import_module
+      ann.raise "ImportModule already specified"
+    end
+
+    if ann.args.size != 1
+      ann.wrong_number_of_arguments "annotation ImportModule", ann.args.size, 1
+    end
+
+    import_module_node = ann.args.first
+    unless import_module_node.is_a?(StringLiteral)
+      import_module_node.raise "argument to CallConvention must be a string"
+    end
+
+    value = import_module_node.value
+    if value.empty?
+      import_module_node.raise "invalid import module. cannot be empty."
+    end
+    value
+  end
+
   def attach_doc(type, node, annotations)
     if @program.wants_doc?
       type.doc ||= node.doc

src/compiler/crystal/types.cr

@@ -2524,6 +2524,7 @@ module Crystal
     getter link_annotations : Array(LinkAnnotation)?
     property? used = false
     property call_convention : LLVM::CallConvention?
+    property import_module : String?
 
     def add_link_annotation(link_annotation : LinkAnnotation)
       link_annotations = @link_annotations ||= [] of LinkAnnotation

src/llvm/enums.cr

@@ -12,6 +12,7 @@ module LLVM
       Convergent
       Dereferenceable
       DereferenceableOrNull
+      ImportModule
       InAlloca
       InReg
       InaccessibleMemOnly
@@ -88,6 +89,7 @@ module LLVM
         kinds[Convergent] = kind_for_name("convergent")
         kinds[Dereferenceable] = kind_for_name("dereferenceable")
         kinds[DereferenceableOrNull] = kind_for_name("dereferenceable_or_null")
+        kinds[ImportModule] = kind_for_name("import_module")
         kinds[InAlloca] = kind_for_name("inalloca")
         kinds[InReg] = kind_for_name("inreg")
         kinds[InaccessibleMemOnly] = kind_for_name("inaccessiblememonly")