Merge #1150

1150: backend: handle link_section attribute r=philberty a=liushuyu

- handle the `link_section` attribute

Co-authored-by: liushuyu <liushuyu011@gmail.com>

gcc/rust/backend/rust-compile-base.cc

@@ -56,6 +56,8 @@ HIRCompileBase::setup_attributes_on_fndecl (
       bool is_must_use
 	= attr.get_path ().as_string ().compare ("must_use") == 0;
       bool is_cold = attr.get_path ().as_string ().compare ("cold") == 0;
+      bool is_link_section
+	= attr.get_path ().as_string ().compare ("link_section") == 0;
       if (is_inline)
 	{
 	  handle_inline_attribute_on_fndecl (fndecl, attr);
@@ -68,6 +70,10 @@ HIRCompileBase::setup_attributes_on_fndecl (
 	{
 	  handle_cold_attribute_on_fndecl (fndecl, attr);
 	}
+      else if (is_link_section)
+	{
+	  handle_link_section_attribute_on_fndecl (fndecl, attr);
+	}
     }
 }
 
@@ -89,6 +95,31 @@ HIRCompileBase::handle_cold_attribute_on_fndecl (tree fndecl,
 		 "attribute %<cold%> does not accept any arguments");
 }
 
+void
+HIRCompileBase::handle_link_section_attribute_on_fndecl (
+  tree fndecl, const AST::Attribute &attr)
+{
+  if (!attr.has_attr_input ())
+    {
+      rust_error_at (attr.get_locus (),
+		     "%<link_section%> expects exactly one argment");
+      return;
+    }
+
+  rust_assert (attr.get_attr_input ().get_attr_input_type ()
+	       == AST::AttrInput::AttrInputType::LITERAL);
+
+  auto &literal = static_cast<AST::AttrInputLiteral &> (attr.get_attr_input ());
+  const auto &msg_str = literal.get_literal ().as_string ();
+
+  if (decl_section_name (fndecl))
+    {
+      rust_warning_at (attr.get_locus (), 0, "section name redefined");
+    }
+
+  set_decl_section_name (fndecl, msg_str.c_str ());
+}
+
 void
 HIRCompileBase::handle_inline_attribute_on_fndecl (tree fndecl,
 						   const AST::Attribute &attr)

gcc/rust/backend/rust-compile-base.h

@@ -88,6 +88,10 @@ protected:
   static void handle_must_use_attribute_on_fndecl (tree fndecl,
 						   const AST::Attribute &attr);
 
+  static void
+  handle_link_section_attribute_on_fndecl (tree fndecl,
+					   const AST::Attribute &attr);
+
   static void setup_abi_options (tree fndecl, ABI abi);
 
   static tree address_expression (tree, Location);

gcc/rust/util/rust-attributes.cc

@@ -31,6 +31,7 @@ static const BuiltinAttrDefinition __definitions[] = {
   {"doc", HIR_LOWERING},
   {"must_use", STATIC_ANALYSIS},
   {"lang", HIR_LOWERING},
+  {"link_section", CODE_GENERATION},
 };
 
 BuiltinAttributeMappings *

gcc/testsuite/rust/debug/custom_link_section.rs

@@ -0,0 +1,13 @@
+#[link_section = ".universe"]
+fn not_in_text() -> i32 {
+    42
+}
+
+fn main() -> i32 {
+// { dg-do compile }
+// { dg-options "-gdwarf-5 -dA -w" }
+    not_in_text();
+// { dg-final { scan-assembler ".universe" } } */
+
+    0
+}