When laying out bases in, always try the "base subobject" LLVM type. If it

turns out that a field or base needs to be laid out in the tail padding of
the base, CGRecordLayoutBuilder::ResizeLastBaseFieldIfNecessary will convert
it to an array of i8.

I've audited the new test results to make sure that they are still valid. I've
also verified that we pass a self-host with this change.

This (finally) fixes PR5589!



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@129673 91177308-0d34-0410-b5e6-96231b3b80d8

6 files changed, 107 insertions, 25 deletions

diff --git a/lib/CodeGen/CGRecordLayoutBuilder.cpp b/lib/CodeGen/CGRecordLayoutBuilder.cpp
index 8f070f3e1c..5a8115639d 100644
--- a/lib/CodeGen/CGRecordLayoutBuilder.cpp
+++ b/lib/CodeGen/CGRecordLayoutBuilder.cpp
@@ -81,9 +81,19 @@ public:
 private:
   CodeGenTypes &Types;
 
+  /// LastLaidOutBaseInfo - Contains the offset and non-virtual size of the
+  /// last base laid out. Used so that we can replace the last laid out base
+  /// type with an i8 array if needed.
+  struct LastLaidOutBaseInfo {
+    CharUnits Offset;
+    CharUnits NonVirtualSize;
+
+    bool isValid() const { return !NonVirtualSize.isZero(); }
+    void invalidate() { NonVirtualSize = CharUnits::Zero(); }
+  
+  } LastLaidOutBase;
+
   /// Alignment - Contains the alignment of the RecordDecl.
-  //
-  // FIXME: This is not needed and should be removed.
   CharUnits Alignment;
 
   /// BitsAvailableInLastField - If a bit field spans only part of a LLVM field,
@@ -143,6 +153,12 @@ private:
   /// struct size is a multiple of the field alignment.
   void AppendPadding(CharUnits fieldOffset, CharUnits fieldAlignment);
 
+  /// ResizeLastBaseFieldIfNecessary - Fields and bases can be laid out in the
+  /// tail padding of a previous base. If this happens, the type of the previous
+  /// base needs to be changed to an array of i8. Returns true if the last
+  /// laid out base was resized.
+  bool ResizeLastBaseFieldIfNecessary(CharUnits offset);
+
   /// getByteArrayType - Returns a byte array type with the given number of
   /// elements.
   const llvm::Type *getByteArrayType(CharUnits NumBytes);
@@ -190,6 +206,7 @@ void CGRecordLayoutBuilder::Layout(const RecordDecl *D) {
 
   // We weren't able to layout the struct. Try again with a packed struct
   Packed = true;
+  LastLaidOutBase.invalidate();
   NextFieldOffset = CharUnits::Zero();
   FieldTypes.clear();
   Fields.clear();
@@ -334,6 +351,17 @@ void CGRecordLayoutBuilder::LayoutBitField(const FieldDecl *D,
   uint64_t nextFieldOffsetInBits = Types.getContext().toBits(NextFieldOffset);
   unsigned numBytesToAppend;
 
+  if (fieldOffset < nextFieldOffsetInBits && !BitsAvailableInLastField) {
+    assert(fieldOffset % 8 == 0 && "Field offset not aligned correctly");
+
+    CharUnits fieldOffsetInCharUnits = 
+      Types.getContext().toCharUnitsFromBits(fieldOffset);
+
+    // Try to resize the last base field.
+    if (ResizeLastBaseFieldIfNecessary(fieldOffsetInCharUnits))
+      nextFieldOffsetInBits = Types.getContext().toBits(NextFieldOffset);
+  }
+
   if (fieldOffset < nextFieldOffsetInBits) {
     assert(BitsAvailableInLastField && "Bitfield size mismatch!");
     assert(!NextFieldOffset.isZero() && "Must have laid out at least one byte");
@@ -411,6 +439,14 @@ bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D,
     NextFieldOffset.RoundUpToAlignment(typeAlignment);
 
   if (fieldOffsetInBytes < alignedNextFieldOffsetInBytes) {
+    // Try to resize the last base field.
+    if (ResizeLastBaseFieldIfNecessary(fieldOffsetInBytes)) {
+      alignedNextFieldOffsetInBytes = 
+        NextFieldOffset.RoundUpToAlignment(typeAlignment);
+    }
+  }
+
+  if (fieldOffsetInBytes < alignedNextFieldOffsetInBytes) {
     assert(!Packed && "Could not place field even with packed struct!");
     return false;
   }
@@ -421,6 +457,7 @@ bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D,
   Fields[D] = FieldTypes.size();
   AppendField(fieldOffsetInBytes, Ty);
 
+  LastLaidOutBase.invalidate();
   return true;
 }
 
@@ -516,11 +553,16 @@ void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) {
 void CGRecordLayoutBuilder::LayoutBase(const CXXRecordDecl *base,
                                        const CGRecordLayout &baseLayout,
                                        CharUnits baseOffset) {
+  ResizeLastBaseFieldIfNecessary(baseOffset);
+
   AppendPadding(baseOffset, CharUnits::One());
 
   const ASTRecordLayout &baseASTLayout
     = Types.getContext().getASTRecordLayout(base);
 
+  LastLaidOutBase.Offset = NextFieldOffset;
+  LastLaidOutBase.NonVirtualSize = baseASTLayout.getNonVirtualSize();
+
   // Fields and bases can be laid out in the tail padding of previous
   // bases.  If this happens, we need to allocate the base as an i8
   // array; otherwise, we can use the subobject type.  However,
@@ -529,20 +571,10 @@ void CGRecordLayoutBuilder::LayoutBase(const CXXRecordDecl *base,
   // approximation, which is to use the base subobject type if it
   // has the same LLVM storage size as the nvsize.
 
-  // The nvsize, i.e. the unpadded size of the base class.
-  CharUnits nvsize = baseASTLayout.getNonVirtualSize();
-
-#if 0
   const llvm::StructType *subobjectType = baseLayout.getBaseSubobjectLLVMType();
-  const llvm::StructLayout *baseLLVMLayout =
-    Types.getTargetData().getStructLayout(subobjectType);
-  CharUnits stsize = CharUnits::fromQuantity(baseLLVMLayout->getSizeInBytes());
+  AppendField(baseOffset, subobjectType);
 
-  if (nvsize == stsize)
-    AppendField(baseOffset, subobjectType);
-  else 
-#endif
-    AppendBytes(nvsize);
+  Types.addBaseSubobjectTypeName(base, baseLayout);
 }
 
 void CGRecordLayoutBuilder::LayoutNonVirtualBase(const CXXRecordDecl *base,
@@ -734,6 +766,8 @@ void CGRecordLayoutBuilder::AppendTailPadding(uint64_t RecordSize) {
 
   CharUnits RecordSizeInBytes =
     Types.getContext().toCharUnitsFromBits(RecordSize);
+  ResizeLastBaseFieldIfNecessary(RecordSizeInBytes);
+
   assert(NextFieldOffset <= RecordSizeInBytes && "Size mismatch!");
 
   CharUnits AlignedNextFieldOffset =
@@ -777,6 +811,24 @@ void CGRecordLayoutBuilder::AppendPadding(CharUnits fieldOffset,
   }
 }
 
+bool CGRecordLayoutBuilder::ResizeLastBaseFieldIfNecessary(CharUnits offset) {
+  // Check if we have a base to resize.
+  if (!LastLaidOutBase.isValid())
+    return false;
+
+  // This offset does not overlap with the tail padding.
+  if (offset >= NextFieldOffset)
+    return false;
+
+  // Restore the field offset and append an i8 array instead.
+  FieldTypes.pop_back();
+  NextFieldOffset = LastLaidOutBase.Offset;
+  AppendBytes(LastLaidOutBase.NonVirtualSize);
+  LastLaidOutBase.invalidate();
+
+  return true;
+}
+
 const llvm::Type *CGRecordLayoutBuilder::getByteArrayType(CharUnits numBytes) {
   assert(!numBytes.isZero() && "Empty byte arrays aren't allowed.");
 
diff --git a/test/CodeGenCXX/class-layout.cpp b/test/CodeGenCXX/class-layout.cpp
index 6675b4963b..672ce03f30 100644
--- a/test/CodeGenCXX/class-layout.cpp
+++ b/test/CodeGenCXX/class-layout.cpp
@@ -17,3 +17,31 @@ namespace Test3 {
   // CHECK: %"struct.Test3::A" = type { i32 (...)**, i32 }
   struct A { virtual void f(); int a; } *a;
 }
+
+namespace Test4 {
+  // Test from PR5589.
+  // CHECK: %"struct.Test4::A" = type { i32, i8, float }
+  // CHECK: %"struct.Test4::B" = type { %"struct.Test4::A", i16, double }
+  struct A {
+    int a;
+    char c;
+    float b;
+  };
+  struct B : public A {
+    short d;
+    double e;
+  } *b;
+}
+
+namespace Test5 {
+  struct A {
+    virtual void f();
+    char a;
+  };
+
+  // CHECK: %"struct.Test4::B" = type { [9 x i8], i8, i8, [5 x i8] }
+  struct B : A {
+    char b : 1;
+    char c;
+  } *b;
+}
diff --git a/test/CodeGenCXX/global-init.cpp b/test/CodeGenCXX/global-init.cpp
index f9eeb59145..9bd7390d07 100644
--- a/test/CodeGenCXX/global-init.cpp
+++ b/test/CodeGenCXX/global-init.cpp
@@ -20,8 +20,8 @@ struct D { ~D(); };
 
 // PR6205: The casts should not require global initializers
 // CHECK: @_ZN6PR59741cE = external global %"struct.PR5974::C"
-// CHECK: @_ZN6PR59741aE = global %"struct.PR5974::A"* bitcast (%"struct.PR5974::C"* @_ZN6PR59741cE to %"struct.PR5974::A"*), align 8
-// CHECK: @_ZN6PR59741bE = global %"struct.PR5974::A"* bitcast (i8* getelementptr (%"struct.PR5974::C"* @_ZN6PR59741cE, i32 0, i32 0, i64 4) to %"struct.PR5974::A"*), align 8
+// CHECK: @_ZN6PR59741aE = global %"struct.PR5974::A"* getelementptr inbounds (%"struct.PR5974::C"* @_ZN6PR59741cE, i32 0, i32 0)
+// CHECK: @_ZN6PR59741bE = global %"struct.PR5974::A"* bitcast (i8* getelementptr (i8* bitcast (%"struct.PR5974::C"* @_ZN6PR59741cE to i8*), i64 4) to %"struct.PR5974::A"*), align 8
 
 // CHECK: call void @_ZN1AC1Ev(%struct.A* @a)
 // CHECK: call i32 @__cxa_atexit(void (i8*)* bitcast (void (%struct.A*)* @_ZN1AD1Ev to void (i8*)*), i8* getelementptr inbounds (%struct.A* @a, i32 0, i32 0), i8* bitcast (i8** @__dso_handle to i8*))
diff --git a/test/CodeGenCXX/pointers-to-data-members.cpp b/test/CodeGenCXX/pointers-to-data-members.cpp
index 40723a856c..2a22d23e50 100644
--- a/test/CodeGenCXX/pointers-to-data-members.cpp
+++ b/test/CodeGenCXX/pointers-to-data-members.cpp
@@ -55,7 +55,7 @@ namespace ZeroInit {
   };
 
   struct C : A, B { int j; };
-  // CHECK-GLOBAL: @_ZN8ZeroInit1cE = global {{%.*}} { [16 x i8] c"\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00", [176 x i8] c"\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF", i32 0, [4 x i8] zeroinitializer }
+  // CHECK-GLOBAL: @_ZN8ZeroInit1cE = global {{%.*}} { %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.ZeroInit::B" { [10 x %"struct.PR7139::ptr_to_member_struct"] [%"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }, %"struct.PR7139::ptr_to_member_struct" { i64 -1, i32 0 }], i8 0, i64 -1 }, i32 0 }, align 8
   C c;
 }
 
@@ -172,15 +172,15 @@ struct A {
   int A::*i;
 };
 
-// CHECK-GLOBAL: @_ZN12VirtualBases1bE = global {{%.*}} { i32 (...)** null, [16 x i8] c"\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF" }
+// CHECK-GLOBAL: @_ZN12VirtualBases1bE = global %"struct.VirtualBases::B" { i32 (...)** null, %"struct.VirtualBases::A" { i8 0, i64 -1 } }, align 8
 struct B : virtual A { };
 B b;
 
-// CHECK-GLOBAL: @_ZN12VirtualBases1cE = global {{%.*}} { i32 (...)** null, i64 -1, [16 x i8] c"\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF" }
+// CHECK-GLOBAL: @_ZN12VirtualBases1cE = global %"struct.VirtualBases::C" { i32 (...)** null, i64 -1, %"struct.VirtualBases::A" { i8 0, i64 -1 } }, align 8
 struct C : virtual A { int A::*i; };
 C c;
 
-  // CHECK-GLOBAL: @_ZN12VirtualBases1dE = global {{%.*}} { [16 x i8] c"\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF", i64 -1, [16 x i8] c"\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF" }
+// CHECK-GLOBAL: @_ZN12VirtualBases1dE = global %"struct.VirtualBases::D" { %"struct.VirtualBases::C.base" { i32 (...)** null, i64 -1 }, i64 -1, %"struct.VirtualBases::A" { i8 0, i64 -1 } }, align 8
 struct D : C { int A::*i; };
 D d;
 
@@ -227,6 +227,6 @@ namespace test4 {
   struct C : virtual B { int    *C_p; };
   struct D :         C { int    *D_p; };
 
-  // CHECK-GLOBAL: @_ZN5test41dE = global {{%.*}} { [16 x i8] zeroinitializer, i32* null, [16 x i8] c"\00\00\00\00\00\00\00\00\FF\FF\FF\FF\FF\FF\FF\FF", [4 x i8] zeroinitializer }
+  // CHECK-GLOBAL: @_ZN5test41dE = global %"struct.test4::D" { %"struct.test4::C.base" zeroinitializer, i32* null, %"struct.VirtualBases::C.base" { i32 (...)** null, i64 -1 }, %"struct.test4::A" zeroinitializer }, align 8
   D d;
 }
diff --git a/test/CodeGenCXX/pragma-pack.cpp b/test/CodeGenCXX/pragma-pack.cpp
index c0ddb1d855..c0b0259784 100644
--- a/test/CodeGenCXX/pragma-pack.cpp
+++ b/test/CodeGenCXX/pragma-pack.cpp
@@ -10,5 +10,7 @@ struct Sub : virtual Base {
   char c;
 };
 
-// CHECK: %struct.Sub = type <{ i32 (...)**, i8, [8 x i8] }>
+// CHECK: %struct.Sub = type <{ i32 (...)**, i8, %struct.Base }>
 void f(Sub*) { }
+
+static int i[sizeof(Sub) == 13 ? 1 : -1];
diff --git a/test/CodeGenCXX/x86_64-arguments.cpp b/test/CodeGenCXX/x86_64-arguments.cpp
index e7316989fe..01f1a445b1 100644
--- a/test/CodeGenCXX/x86_64-arguments.cpp
+++ b/test/CodeGenCXX/x86_64-arguments.cpp
@@ -3,13 +3,13 @@
 // Basic base class test.
 struct f0_s0 { unsigned a; };
 struct f0_s1 : public f0_s0 { void *b; };
-// CHECK: define void @_Z2f05f0_s1(i64 %a0.coerce0, i8* %a0.coerce1)
+// CHECK: define void @_Z2f05f0_s1(i32 %a0.coerce0, i8* %a0.coerce1)
 void f0(f0_s1 a0) { }
 
 // Check with two eight-bytes in base class.
 struct f1_s0 { unsigned a; unsigned b; float c; };
 struct f1_s1 : public f1_s0 { float d;};
-// CHECK: define void @_Z2f15f1_s1(i64 %a0.coerce0, double %a0.coerce1)
+// CHECK: define void @_Z2f15f1_s1(i64 %a0.coerce0, <2 x float> %a0.coerce1)
 void f1(f1_s1 a0) { }
 
 // Check with two eight-bytes in base class and merge.
@@ -54,7 +54,7 @@ namespace PR7742 { // Also rdar://8250764
   
   struct c2 : public s2 {};
   
-  // CHECK: define double @_ZN6PR77423fooEPNS_2c2E(%"struct.PR7742::c2"* %P)
+  // CHECK: define <2 x float> @_ZN6PR77423fooEPNS_2c2E(%"struct.PR7742::c2"* %P)
   c2 foo(c2 *P) {
   }