[assembly-vision] Add function attribute '@_assemblyVision'

This is just a shortcut for @_semantics("optremark") to make it easier for
people to remember how to enable assembly vision remarks.

Now one can just type:

```
@_assemblyVision
func foo() {
  ...
}
```

and get all normal opt-remarks + assembly vision remarks.

Author: gottesmm

include/swift/AST/Attr.def

@@ -672,6 +672,11 @@ SIMPLE_DECL_ATTR(_distributedActorIndependent, DistributedActorIndependent,
   APIBreakingToAdd | APIBreakingToRemove,
   119)
 
+SIMPLE_DECL_ATTR(_assemblyVision, EmitAssemblyVisionRemarks,
+  OnFunc | UserInaccessible | NotSerialized |
+  ABIStableToAdd | ABIStableToRemove | APIStableToAdd | APIStableToRemove,
+  120)
+
 #undef TYPE_ATTR
 #undef DECL_ATTR_ALIAS
 #undef CONTEXTUAL_DECL_ATTR_ALIAS

lib/SIL/IR/SILFunctionBuilder.cpp

@@ -11,8 +11,11 @@
 //===----------------------------------------------------------------------===//
 
 #include "swift/SIL/SILFunctionBuilder.h"
+#include "swift/AST/AttrKind.h"
 #include "swift/AST/Availability.h"
 #include "swift/AST/Decl.h"
+#include "swift/AST/SemanticAttrs.h"
+
 using namespace swift;
 
 SILFunction *SILFunctionBuilder::getOrCreateFunction(
@@ -45,6 +48,13 @@ void SILFunctionBuilder::addFunctionAttributes(
   for (auto *A : Attrs.getAttributes<SemanticsAttr>())
     F->addSemanticsAttr(cast<SemanticsAttr>(A)->Value);
 
+  // If we are asked to emit assembly vision remarks for this function, mark the
+  // function as force emitting all optremarks including assembly vision
+  // remarks. This allows us to emit the assembly vision remarks without needing
+  // to change any of the underlying optremark mechanisms.
+  if (auto *A = Attrs.getAttribute(DAK_EmitAssemblyVisionRemarks))
+    F->addSemanticsAttr(semantics::FORCE_EMIT_OPT_REMARK_PREFIX);
+
   // Propagate @_specialize.
   for (auto *A : Attrs.getAttributes<SpecializeAttr>()) {
     auto *SA = cast<SpecializeAttr>(A);

lib/Sema/TypeCheckAttr.cpp

@@ -90,6 +90,7 @@ class AttributeChecker : public AttributeVisitor<AttributeChecker> {
   IGNORED_ATTR(RequiresStoredPropertyInits)
   IGNORED_ATTR(RestatedObjCConformance)
   IGNORED_ATTR(Semantics)
+  IGNORED_ATTR(EmitAssemblyVisionRemarks)
   IGNORED_ATTR(ShowInInterface)
   IGNORED_ATTR(SILGenName)
   IGNORED_ATTR(StaticInitializeObjCMetadata)

lib/Sema/TypeCheckDeclOverride.cpp

@@ -1480,6 +1480,7 @@ namespace  {
     UNINTERESTING_ATTR(Required)
     UNINTERESTING_ATTR(Convenience)
     UNINTERESTING_ATTR(Semantics)
+    UNINTERESTING_ATTR(EmitAssemblyVisionRemarks)
     UNINTERESTING_ATTR(SetterAccess)
     UNINTERESTING_ATTR(TypeEraser)
     UNINTERESTING_ATTR(SPIAccessControl)

lib/Serialization/ModuleFormat.h

@@ -56,7 +56,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 615; // isolated parameters
+const uint16_t SWIFTMODULE_VERSION_MINOR = 616; // @_assemblyVision
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///

test/SILOptimizer/assemblyvision_remark/semantics.swift renamed to test/SILOptimizer/assemblyvision_remark/attributes.swift

@@ -85,3 +85,10 @@ public func mix5() -> (Klass, Klass) {
     let x = getGlobal()
     return (x, Klass())
 }
+
+@_assemblyVision
+public func mix4a() -> (Klass, Klass) {
+    let x = getGlobal()
+    return (x, Klass()) // expected-remark {{Pure call. Always profitable to inline "main.Klass.__allocating_init()"}}
+                        // expected-remark @-1 {{heap allocated ref of type 'Klass'}}
+}