This revision was automatically updated to reflect the committed changes. Closed by commit rC351461: [CodeGenObjC] Use a constant value for non-fragile ivar offsets when possible (authored by epilk, committed by ).
Changed prior to commit: https://reviews.llvm.org/D56802?vs=182214&id=182336#toc Repository: rC Clang CHANGES SINCE LAST ACTION https://reviews.llvm.org/D56802/new/ https://reviews.llvm.org/D56802 Files: lib/CodeGen/CGObjCMac.cpp test/CodeGenObjC/constant-non-fragile-ivar-offset.m test/CodeGenObjC/optimize-ivar-offset-load.m test/CodeGenObjC/reorder-synthesized-ivars.m
Index: lib/CodeGen/CGObjCMac.cpp =================================================================== --- lib/CodeGen/CGObjCMac.cpp +++ lib/CodeGen/CGObjCMac.cpp @@ -1550,6 +1550,15 @@ return false; } + bool isClassLayoutKnownStatically(const ObjCInterfaceDecl *ID) { + // NSObject is a fixed size. If we can see the @implementation of a class + // which inherits from NSObject then we know that all it's offsets also must + // be fixed. FIXME: Can we do this if see a chain of super classes with + // implementations leading to NSObject? + return ID->getImplementation() && ID->getSuperClass() && + ID->getSuperClass()->getName() == "NSObject"; + } + public: CGObjCNonFragileABIMac(CodeGen::CodeGenModule &cgm); @@ -6702,6 +6711,12 @@ IvarOffsetGV->setVisibility(llvm::GlobalValue::DefaultVisibility); } + // If ID's layout is known, then make the global constant. This serves as a + // useful assertion: we'll never use this variable to calculate ivar offsets, + // so if the runtime tries to patch it then we should crash. + if (isClassLayoutKnownStatically(ID)) + IvarOffsetGV->setConstant(true); + if (CGM.getTriple().isOSBinFormatMachO()) IvarOffsetGV->setSection("__DATA, __objc_ivar"); return IvarOffsetGV; @@ -6990,17 +7005,24 @@ Offset); } -llvm::Value *CGObjCNonFragileABIMac::EmitIvarOffset( - CodeGen::CodeGenFunction &CGF, - const ObjCInterfaceDecl *Interface, - const ObjCIvarDecl *Ivar) { - llvm::Value *IvarOffsetValue = ObjCIvarOffsetVariable(Interface, Ivar); - IvarOffsetValue = CGF.Builder.CreateAlignedLoad(IvarOffsetValue, - CGF.getSizeAlign(), "ivar"); - if (IsIvarOffsetKnownIdempotent(CGF, Ivar)) - cast<llvm::LoadInst>(IvarOffsetValue) - ->setMetadata(CGM.getModule().getMDKindID("invariant.load"), - llvm::MDNode::get(VMContext, None)); +llvm::Value * +CGObjCNonFragileABIMac::EmitIvarOffset(CodeGen::CodeGenFunction &CGF, + const ObjCInterfaceDecl *Interface, + const ObjCIvarDecl *Ivar) { + llvm::Value *IvarOffsetValue; + if (isClassLayoutKnownStatically(Interface)) { + IvarOffsetValue = llvm::ConstantInt::get( + ObjCTypes.IvarOffsetVarTy, + ComputeIvarBaseOffset(CGM, Interface->getImplementation(), Ivar)); + } else { + llvm::GlobalVariable *GV = ObjCIvarOffsetVariable(Interface, Ivar); + IvarOffsetValue = + CGF.Builder.CreateAlignedLoad(GV, CGF.getSizeAlign(), "ivar"); + if (IsIvarOffsetKnownIdempotent(CGF, Ivar)) + cast<llvm::LoadInst>(IvarOffsetValue) + ->setMetadata(CGM.getModule().getMDKindID("invariant.load"), + llvm::MDNode::get(VMContext, None)); + } // This could be 32bit int or 64bit integer depending on the architecture. // Cast it to 64bit integer value, if it is a 32bit integer ivar offset value Index: test/CodeGenObjC/constant-non-fragile-ivar-offset.m =================================================================== --- test/CodeGenObjC/constant-non-fragile-ivar-offset.m +++ test/CodeGenObjC/constant-non-fragile-ivar-offset.m @@ -0,0 +1,38 @@ +// RUN: %clang_cc1 -triple x86_64-apple-macosx10.14.0 -emit-llvm %s -o - | FileCheck %s + +// CHECK: @"OBJC_IVAR_$_StaticLayout.static_layout_ivar" = hidden constant i64 20 +// CHECK: @"OBJC_IVAR_$_NotStaticLayout.not_static_layout_ivar" = hidden global i64 12 + +@interface NSObject { + int these, will, never, change, ever; +} +@end + +@interface StaticLayout : NSObject +@end + +@implementation StaticLayout { + int static_layout_ivar; +} +-(void)meth { + static_layout_ivar = 0; + // CHECK-NOT: load i64, i64* @"OBJC_IVAR_$_StaticLayout +} +@end + +@interface NotNSObject { + int these, might, change; +} +@end + +@interface NotStaticLayout : NotNSObject +@end + +@implementation NotStaticLayout { + int not_static_layout_ivar; +} +-(void)meth { + not_static_layout_ivar = 0; + // CHECK: load i64, i64* @"OBJC_IVAR_$_NotStaticLayout.not_static_layout_ivar +} +@end Index: test/CodeGenObjC/optimize-ivar-offset-load.m =================================================================== --- test/CodeGenObjC/optimize-ivar-offset-load.m +++ test/CodeGenObjC/optimize-ivar-offset-load.m @@ -1,17 +1,17 @@ // RUN: %clang_cc1 -triple x86_64-apple-darwin10 -O0 -emit-llvm %s -o - | FileCheck %s // rdar://16095748 -@interface NSObject +@interface MyNSObject @end -@interface SampleClass : NSObject { +@interface SampleClass : MyNSObject { @public int _value; } + (SampleClass*) new; @end -@interface AppDelegate : NSObject +@interface AppDelegate : MyNSObject @end extern void foo(int); Index: test/CodeGenObjC/reorder-synthesized-ivars.m =================================================================== --- test/CodeGenObjC/reorder-synthesized-ivars.m +++ test/CodeGenObjC/reorder-synthesized-ivars.m @@ -39,20 +39,20 @@ @end // CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean1 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean2 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean3 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean4 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean5 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean6 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean7 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean8 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean9 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object1 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object2 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object3 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object4 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object5 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object6 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object7 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object8 -// CHECK-NEXT: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object9 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean2 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean3 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean4 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean5 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean6 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean7 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean8 +// CHECK: @{{.*}} = private unnamed_addr constant [10 x i8] c"_boolean9 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object1 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object2 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object3 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object4 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object5 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object6 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object7 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object8 +// CHECK: @{{.*}} = private unnamed_addr constant [9 x i8] c"_object9
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