[PATCH] D34574: [Sema] Disable c++17 aligned new and delete operators if not implemented in the deployment target's c++ standard library

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak created this revision.

This patch stops declaring implicitly the new and delete operators with alignment if the deployment target is earlier than the version in which support for them was introduced . This fixes linker errors which we see when the compiler emits a new or delete operator with alignment but the c++ library it links against is old and doesn't implement those operators.

I also sent a patch that annotates the declarations in libc++ today:

https://reviews.llvm.org/D34556

rdar://problem/32664169


https://reviews.llvm.org/D34574

Files:
  include/clang/Basic/TargetInfo.h
  lib/Basic/Targets.cpp
  lib/Sema/SemaExprCXX.cpp
  test/CodeGenCXX/cxx1z-aligned-allocation.cpp


Index: test/CodeGenCXX/cxx1z-aligned-allocation.cpp
===================================================================
--- test/CodeGenCXX/cxx1z-aligned-allocation.cpp
+++ test/CodeGenCXX/cxx1z-aligned-allocation.cpp
@@ -3,10 +3,15 @@
 // RUN: %clang_cc1 -std=c++11 -fexceptions -fsized-deallocation -faligned-allocation %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s
 // RUN: %clang_cc1 -std=c++14 -fexceptions -fsized-deallocation -faligned-allocation %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s
 // RUN: %clang_cc1 -std=c++1z -fexceptions -fsized-deallocation %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s
+// RUN: %clang_cc1 -std=c++1z -fexceptions -fsized-deallocation %s -emit-llvm -triple x86_64-apple-darwin10.13 -o - | FileCheck %s
 
 // Check that we don't used aligned (de)allocation without -faligned-allocation or C++1z.
 // RUN: %clang_cc1 -std=c++14 -DUNALIGNED -fexceptions %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
 // RUN: %clang_cc1 -std=c++1z -DUNALIGNED -fexceptions -fno-aligned-allocation %s -emit-llvm -triple x86_64-linux-gnu -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
+// RUN: %clang_cc1 -std=c++1z -DUNALIGNED -fexceptions -fno-aligned-allocation %s -emit-llvm -triple x86_64-apple-darwin10.12 -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
+// RUN: %clang_cc1 -std=c++1z -DUNALIGNED -fexceptions -fno-aligned-allocation %s -emit-llvm -triple arm64-apple-ios10 -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
+// RUN: %clang_cc1 -std=c++1z -DUNALIGNED -fexceptions -fno-aligned-allocation %s -emit-llvm -triple arm64-apple-tvos10 -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
+// RUN: %clang_cc1 -std=c++1z -DUNALIGNED -fexceptions -fno-aligned-allocation %s -emit-llvm -triple thumbv7k-apple-watchos4 -o - | FileCheck %s --check-prefix=CHECK-UNALIGNED
 
 // CHECK-UNALIGNED-NOT: _Znwm_St11align_val_t
 // CHECK-UNALIGNED-NOT: _Znam_St11align_val_t
Index: lib/Sema/SemaExprCXX.cpp
===================================================================
--- lib/Sema/SemaExprCXX.cpp
+++ lib/Sema/SemaExprCXX.cpp
@@ -2580,7 +2580,8 @@
     // Create up to four variants of the function (sized/aligned).
     bool HasSizedVariant = getLangOpts().SizedDeallocation &&
                            (Kind == OO_Delete || Kind == OO_Array_Delete);
-    bool HasAlignedVariant = getLangOpts().AlignedAllocation;
+    bool HasAlignedVariant = getLangOpts().AlignedAllocation &&
+                             !Context.getTargetInfo().disableAlignedAllocation();
 
     int NumSizeVariants = (HasSizedVariant ? 2 : 1);
     int NumAlignVariants = (HasAlignedVariant ? 2 : 1);
Index: lib/Basic/Targets.cpp
===================================================================
--- lib/Basic/Targets.cpp
+++ lib/Basic/Targets.cpp
@@ -292,6 +292,29 @@
     // and therefore doesn't guarantee 16-byte alignment.
     return  64;
   }
+
+  bool disableAlignedAllocation() const override {
+    unsigned Major, Minor, Micro;
+    const llvm::Triple &T = this->getTriple();
+    T.getOSVersion(Major, Minor, Micro);
+
+    switch (T.getOS()) {
+    case llvm::Triple::Darwin:
+    case llvm::Triple::MacOSX: // Earlier than 10.13.
+      if (Major > 10)
+        return false;
+      if (Major < 10)
+        return true;
+      return Minor < 13;
+    case llvm::Triple::IOS:
+    case llvm::Triple::TvOS: // Earlier than 11.0.
+      return Major < 11;
+    case llvm::Triple::WatchOS: // Earlier than 4.0.
+      return Major < 4;
+    default:
+      llvm_unreachable("unexpected OS");
+    }
+  }
 };
 
 
Index: include/clang/Basic/TargetInfo.h
===================================================================
--- include/clang/Basic/TargetInfo.h
+++ include/clang/Basic/TargetInfo.h
@@ -773,6 +773,14 @@
     return true;
   }
 
+  /// Returns true if the target doesn't support c++17's aligned new and
+  /// delete operators. For example, if the deployment target is old and the
+  /// operators are not available in the c++ standard library, this function
+  /// should return true.
+  virtual bool disableAlignedAllocation() const {
+    return false;
+  }
+
   /// \brief Returns the target triple of the primary target.
   const llvm::Triple &getTriple() const {
     return Triple;


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