[PATCH] D105380: [clang] fixes named return of variables with dependent alignment

[Matheus Izvekov via Phabricator via cfe-commits]

mizvekov updated this revision to Diff 356409.
mizvekov marked an inline comment as done.
mizvekov added a comment.

format.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D105380/new/

https://reviews.llvm.org/D105380

Files:
  clang/include/clang/Sema/Sema.h
  clang/lib/Sema/SemaDecl.cpp
  clang/lib/Sema/SemaStmt.cpp
  clang/test/CodeGen/nrvo-tracking.cpp


Index: clang/test/CodeGen/nrvo-tracking.cpp
===================================================================
--- clang/test/CodeGen/nrvo-tracking.cpp
+++ clang/test/CodeGen/nrvo-tracking.cpp
@@ -1,9 +1,9 @@
 // RUN: %clang_cc1 -std=c++20 -fblocks -Wno-return-stack-address -triple x86_64-unknown-unknown-gnu -emit-llvm -O1 -fexperimental-new-pass-manager -o - %s | FileCheck %s
 
-struct X {
-    X();
-    X(const X&);
-    X(X&&);
+struct alignas(4) X {
+  X();
+  X(const X &);
+  X(X &&);
 };
 
 #define L(A, B, C) void l##A() {    \
@@ -210,3 +210,75 @@
     };
   }()();
 }
+
+namespace test_alignas {
+
+template <int A> X t1() {
+  X a [[gnu::aligned(A)]];
+  return a;
+}
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t1ILi1EEE1Xv
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  ret void
+template X t1<1>();
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t1ILi4EEE1Xv
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  ret void
+template X t1<4>();
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t1ILi8EEE1Xv
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  call {{.*}} @_ZN1XC1EOS_
+// CHECK-NEXT:  call void @llvm.lifetime.end
+template X t1<8>();
+
+template <int A> X t2() {
+  X a [[gnu::aligned(1)]] [[gnu::aligned(A)]] [[gnu::aligned(2)]];
+  return a;
+}
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t2ILi1EEE1Xv
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  ret void
+template X t2<1>();
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t2ILi4EEE1Xv
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  ret void
+template X t2<4>();
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t2ILi8EEE1Xv
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  call {{.*}} @_ZN1XC1EOS_
+// CHECK-NEXT:  call void @llvm.lifetime.end
+template X t2<8>();
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t3Ev
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  ret void
+X t3() {
+  X a [[gnu::aligned(1)]];
+  return a;
+}
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t4Ev
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  call {{.*}} @_ZN1XC1EOS_
+// CHECK-NEXT:  call void @llvm.lifetime.end
+X t4() {
+  X a [[gnu::aligned(8)]];
+  return a;
+}
+
+// CHECK-LABEL: define{{.*}} void @_ZN12test_alignas2t5Ev
+// CHECK:       call {{.*}} @_ZN1XC1Ev
+// CHECK-NEXT:  call {{.*}} @_ZN1XC1EOS_
+// CHECK-NEXT:  call void @llvm.lifetime.end
+X t5() {
+  X a [[gnu::aligned(1)]] [[gnu::aligned(8)]];
+  return a;
+}
+
+} // namespace test_alignas
Index: clang/lib/Sema/SemaStmt.cpp
===================================================================
--- clang/lib/Sema/SemaStmt.cpp
+++ clang/lib/Sema/SemaStmt.cpp
@@ -3395,7 +3395,7 @@
 
   // Variables with higher required alignment than their type's ABI
   // alignment cannot use NRVO.
-  if (!VDType->isDependentType() && VD->hasAttr<AlignedAttr>() &&
+  if (!hasDependentAlignment(VD) &&
       Context.getDeclAlign(VD) > Context.getTypeAlignInChars(VDType))
     Info.S = NamedReturnInfo::MoveEligible;
 
Index: clang/lib/Sema/SemaDecl.cpp
===================================================================
--- clang/lib/Sema/SemaDecl.cpp
+++ clang/lib/Sema/SemaDecl.cpp
@@ -13310,14 +13310,12 @@
     CheckCompleteDecompositionDeclaration(DD);
 }
 
-/// Determines if a variable's alignment is dependent.
-static bool hasDependentAlignment(VarDecl *VD) {
-  if (VD->getType()->isDependentType())
-    return true;
-  for (auto *I : VD->specific_attrs<AlignedAttr>())
-    if (I->isAlignmentDependent())
-      return true;
-  return false;
+bool Sema::hasDependentAlignment(const VarDecl *VD) {
+  const auto &range = VD->specific_attrs<AlignedAttr>();
+  return VD->getType()->isDependentType() ||
+         std::any_of(range.begin(), range.end(), [](const AlignedAttr *AA) {
+           return AA->isAlignmentDependent();
+         });
 }
 
 /// Check if VD needs to be dllexport/dllimport due to being in a
Index: clang/include/clang/Sema/Sema.h
===================================================================
--- clang/include/clang/Sema/Sema.h
+++ clang/include/clang/Sema/Sema.h
@@ -2666,6 +2666,9 @@
   /// it looks like the user is trying to modify the shadowing declaration.
   llvm::DenseMap<const NamedDecl *, const NamedDecl *> ShadowingDecls;
 
+  /// Determines if a variable's alignment is dependent.
+  static bool hasDependentAlignment(const VarDecl *VD);
+
 public:
   void CheckCastAlign(Expr *Op, QualType T, SourceRange TRange);
   void handleTagNumbering(const TagDecl *Tag, Scope *TagScope);

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