Use Clang's logic for adding the default IR attributes to a function.

A lot of attributes are essentially default target configuration, and we should only differ when there's a good reason to.

For the attributes we were already setting:
- the ptrauth and target CPU/feature attributes are taken care of by Clang
- I've updated the optsize/minsize attributes to the apparent intent
- I've left the frame-pointer override in place for now

Fixes rdar://63289339, which was caused by Swift's ptrauth IR attributes getting out of sync with Clang's.

Author: rjmccall

lib/IRGen/IRGenModule.cpp

@@ -1001,42 +1001,22 @@ void IRGenModule::setHasFramePointer(llvm::Function *F,
 /// Construct initial function attributes from options.
 void IRGenModule::constructInitialFnAttributes(llvm::AttrBuilder &Attrs,
                                                OptimizationMode FuncOptMode) {
+  // Add the default attributes for the Clang configuration.
+  clang::CodeGen::addDefaultFunctionDefinitionAttributes(getClangCGM(), Attrs);
+
   // Add frame pointer attributes.
+  // FIXME: why are we doing this?
   setHasFramePointer(Attrs, IRGen.Opts.DisableFPElim);
 
-  // Add target-cpu and target-features if they are non-null.
-  auto *Clang = static_cast<ClangImporter *>(Context.getClangModuleLoader());
-  clang::TargetOptions &ClangOpts = Clang->getTargetInfo().getTargetOpts();
-
-  std::string &CPU = ClangOpts.CPU;
-  if (CPU != "")
-    Attrs.addAttribute("target-cpu", CPU);
-
-  std::vector<std::string> Features;
-  for (auto &F : ClangOpts.Features)
-    if (!shouldRemoveTargetFeature(F))
-        Features.push_back(F);
-
-  if (!Features.empty()) {
-    SmallString<64> allFeatures;
-    // Sort so that the target features string is canonical.
-    std::sort(Features.begin(), Features.end());
-    llvm::interleave(Features, [&](const std::string &s) {
-      allFeatures.append(s);
-    }, [&]{
-      allFeatures.push_back(',');
-    });
-    Attrs.addAttribute("target-features", allFeatures);
-  }
+  // Add/remove MinSize based on the appropriate setting.
   if (FuncOptMode == OptimizationMode::NotSet)
     FuncOptMode = IRGen.Opts.OptMode;
-  if (FuncOptMode == OptimizationMode::ForSize)
+  if (FuncOptMode == OptimizationMode::ForSize) {
+    Attrs.addAttribute(llvm::Attribute::OptimizeForSize);
     Attrs.addAttribute(llvm::Attribute::MinSize);
-
-  auto triple = llvm::Triple(ClangOpts.Triple);
-  if (triple.getArchName() == "arm64e") {
-    Attrs.addAttribute("ptrauth-returns");
-    Attrs.addAttribute("ptrauth-calls");
+  } else {
+    Attrs.removeAttribute(llvm::Attribute::MinSize);
+    Attrs.removeAttribute(llvm::Attribute::OptimizeForSize);
   }
 }
 

test/IRGen/c_globals.swift

@@ -32,4 +32,4 @@ public func testCaptureGlobal() {
 }
 
 // CHECK-DAG: attributes [[CLANG_FUNC_ATTR]] = { noinline nounwind {{.*}}"frame-pointer"="all"{{.*}}
-// CHECK-DAG: attributes [[SWIFT_FUNC_ATTR]] = { "frame-pointer"="all" {{.*}}"target-cpu"
+// CHECK-DAG: attributes [[SWIFT_FUNC_ATTR]] = { {{.*}}"frame-pointer"="all" {{.*}}"target-cpu"

test/IRGen/generic_metatypes.swift

@@ -146,4 +146,4 @@ func makeGenericMetatypes() {
 // CHECK:   ret %swift.metadata_response
 
 // CHECK-DAG: attributes [[NOUNWIND_READNONE]] = { nounwind readnone }
-// CHECK-DAG: attributes [[NOUNWIND_OPT]] = { noinline nounwind "frame-pointer"="none" "target-cpu"
+// CHECK-DAG: attributes [[NOUNWIND_OPT]] = { noinline nounwind "

test/IRGen/generic_metatypes_future.swift

@@ -176,4 +176,4 @@ func makeGenericMetatypes() {
 // CHECK:   ret %swift.metadata_response
 
 // CHECK-DAG: attributes [[NOUNWIND_READNONE]] = { nounwind readnone }
-// CHECK-DAG: attributes [[NOUNWIND_OPT]] = { noinline nounwind "frame-pointer"="none" "target-cpu"
+// CHECK-DAG: attributes [[NOUNWIND_OPT]] = { noinline nounwind "

test/IRGen/ptrauth-functions.sil

@@ -87,4 +87,4 @@ bb0(%0 : $T):
 
 sil_vtable F {
 }
-// CHECK: #[[ATTRS]] = {{{.*}} "ptrauth-calls" "ptrauth-returns"
+// CHECK: #[[ATTRS]] = {{{.*}} "ptrauth-auth-traps" "ptrauth-calls" "ptrauth-indirect-gotos" "ptrauth-returns"

test/SILOptimizer/opt_mode.swift

@@ -47,5 +47,5 @@ func test_ospeed(_ a: A) -> Int {
 }
 
 
-// CHECK-IR: attributes [[SIZE_ATTR]] = { minsize "
+// CHECK-IR: attributes [[SIZE_ATTR]] = { minsize optsize "
 // CHECK-IR: attributes [[NOSIZE_ATTR]] = { "