[clang] [ObjC] Check entire chain of superclasses to see if class layout can be statically known (PR #81335)
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Thu Feb 22 16:34:48 PST 2024
https://github.com/AtariDreams updated https://github.com/llvm/llvm-project/pull/81335
>From 6c46f5be980dac3200058b694ab7fca3f6ad707e Mon Sep 17 00:00:00 2001
From: Rose <83477269+AtariDreams at users.noreply.github.com>
Date: Fri, 9 Feb 2024 17:51:15 -0500
Subject: [PATCH 1/2] [ObjC] Add pre-commit tests [NFC]
---
.../constant-non-fragile-ivar-offset.m | 96 +++++++++++++++++++
1 file changed, 96 insertions(+)
diff --git a/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m b/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m
index 788b3220af3067..c4bb1ebc9a80be 100644
--- a/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m
+++ b/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m
@@ -1,6 +1,13 @@
// RUN: %clang_cc1 -triple x86_64-apple-macosx10.14.0 -emit-llvm %s -o - | FileCheck %s
// CHECK: @"OBJC_IVAR_$_StaticLayout.static_layout_ivar" = hidden constant i64 20
+// CHECK: @"OBJC_IVAR_$_SuperClass.superClassIvar" = hidden constant i64 20
+// CHECK: @"OBJC_IVAR_$_SuperClass._superClassProperty" = hidden constant i64 24
+// CHECK: @"OBJC_IVAR_$_IntermediateClass.intermediateClassIvar" = global i64 32
+// CHECK: @"OBJC_IVAR_$_IntermediateClass.intermediateClassIvar2" = global i64 40
+// CHECK: @"OBJC_IVAR_$_IntermediateClass._intermediateProperty" = hidden global i64 48
+// CHECK: @"OBJC_IVAR_$_SubClass.subClassIvar" = global i64 56
+// CHECK: @"OBJC_IVAR_$_SubClass._subClassProperty" = hidden global i64 64
// CHECK: @"OBJC_IVAR_$_NotStaticLayout.not_static_layout_ivar" = hidden global i64 12
@interface NSObject {
@@ -20,6 +27,95 @@ -(void)meth {
}
@end
+// Ivars declared in the @interface
+ at interface SuperClass : NSObject
+ at property (nonatomic, assign) int superClassProperty;
+ at end
+
+ at implementation SuperClass {
+ int superClassIvar; // Declare an ivar
+}
+
+// CHECK-LABEL: define internal void @"\01-[SuperClass superClassMethod]"
+- (void)superClassMethod {
+ _superClassProperty = 42;
+ superClassIvar = 10;
+ // CHECK: load i64, ptr @"OBJC_IVAR_$_SuperClass
+ // CHECK: getelementptr inbounds i8, ptr %1, i64 20
+}
+
+// implicitly synthesized method here
+// CHECK-LABEL: define internal i32 @"\01-[SuperClass superClassProperty]"
+// CHECK: getelementptr inbounds i8, ptr %0, i64 24
+
+// CHECK-LABEL: define internal void @"\01-[SuperClass setSuperClassProperty:]"
+// CHECK: getelementptr inbounds i8, ptr %1, i64 24
+ at end
+
+// Inheritance and Ivars
+ at interface IntermediateClass : SuperClass
+{
+ double intermediateClassIvar;
+
+ @protected
+ int intermediateClassIvar2;
+}
+ at property (nonatomic, strong) SuperClass *intermediateProperty;
+ at end
+
+ at implementation IntermediateClass
+ at synthesize intermediateProperty = _intermediateProperty;
+- (void)intermediateClassMethod {
+ intermediateClassIvar = 3.14;
+ // CHECK: load i64, ptr @"OBJC_IVAR_$_IntermediateClass
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 %ivar
+}
+
+// CHECK-LABEL: define internal void @"\01-[IntermediateClass intermediateClassPropertyMethod]"
+- (void)intermediateClassPropertyMethod {
+ self.intermediateProperty = 0;
+ // CHECK: load ptr, ptr @OBJC_SELECTOR_REFERENCES_
+ // CHECK: call void @objc_msgSend(ptr noundef %0, ptr noundef %1, ptr noundef null)
+}
+
+// CHECK-LABEL: define internal void @"\01-[IntermediateClass intermediateClassPropertyMethodDirect]"
+- (void)intermediateClassPropertyMethodDirect {
+ _intermediateProperty = 0;
+ // CHECK: load i64, ptr @"OBJC_IVAR_$_IntermediateClass._intermediateProperty"
+}
+ at end
+
+ at interface SubClass : IntermediateClass
+{
+ double subClassIvar;
+}
+ at property (nonatomic, assign) SubClass *subClassProperty;
+ at end
+
+ at implementation SubClass
+// CHECK-LABEL: define internal void @"\01-[SubClass subclassVar]"
+- (void)subclassVar {
+
+ subClassIvar = 6.28;
+ // CHECK: load i64, ptr @"OBJC_IVAR_$_SubClass
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 %ivar
+}
+
+// CHECK-LABEL: define internal void @"\01-[SubClass intermediateSubclassVar]"
+-(void)intermediateSubclassVar {
+ intermediateClassIvar = 3.14;
+ // CHECK: load i64, ptr @"OBJC_IVAR_$_IntermediateClass
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 %ivar
+}
+
+// implicit synthesized method here:
+// CHECK-LABEL: define internal ptr @"\01-[SubClass subClassProperty]"
+// CHECK: load i64, ptr @"OBJC_IVAR_$_SubClass._subClassProperty"
+
+// CHECK-LABEL: define internal void @"\01-[SubClass setSubClassProperty:]"
+// CHECK: load i64, ptr @"OBJC_IVAR_$_SubClass._subClassProperty"
+ at end
+
@interface NotNSObject {
int these, might, change;
}
>From 7907980a315c86e43b14d1fc137fc655bbfd2dc3 Mon Sep 17 00:00:00 2001
From: Rose <83477269+AtariDreams at users.noreply.github.com>
Date: Tue, 13 Feb 2024 14:52:49 -0500
Subject: [PATCH 2/2] [ObjC] Check entire chain of superclasses to see if class
layout can be statically known
As of now, we only check if a class directly inherits from NSObject to determine if said class has fixed offsets and can therefore have its memory layout statically known.
However, if an NSObject subclass has fixed offsets, then so must the subclasses of that subclass, so this allows us to optimize instances of subclasses of subclasses that inherit from NSObject and so on.
To determine this, we need to find that the compiler can see the implementation of each intermediate class, as that means it is statically linked.
---
clang/lib/CodeGen/CGObjCMac.cpp | 23 ++++++++----
.../constant-non-fragile-ivar-offset.m | 35 ++++++++++---------
2 files changed, 36 insertions(+), 22 deletions(-)
diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
index 27d77e9a8a5511..c7ec2370f56285 100644
--- a/clang/lib/CodeGen/CGObjCMac.cpp
+++ b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -1593,12 +1593,23 @@ class CGObjCNonFragileABIMac : public CGObjCCommonMac {
}
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";
+ // Test a class by checking its superclasses up to
+ // its base class if it has one.
+ while (ID) {
+ // The layout of base class NSObject
+ // is guaranteed to be statically known
+ if (ID->getName() == "NSObject")
+ return true;
+
+ // If we cannot see the @implementation of a class,
+ // we cannot statically know the class layout.
+ if (!ID->getImplementation())
+ return false;
+
+ // Test superclass
+ ID = ID->getSuperClass();
+ }
+ return false;
}
public:
diff --git a/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m b/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m
index c4bb1ebc9a80be..8b689936691b8d 100644
--- a/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m
+++ b/clang/test/CodeGenObjC/constant-non-fragile-ivar-offset.m
@@ -3,11 +3,11 @@
// CHECK: @"OBJC_IVAR_$_StaticLayout.static_layout_ivar" = hidden constant i64 20
// CHECK: @"OBJC_IVAR_$_SuperClass.superClassIvar" = hidden constant i64 20
// CHECK: @"OBJC_IVAR_$_SuperClass._superClassProperty" = hidden constant i64 24
-// CHECK: @"OBJC_IVAR_$_IntermediateClass.intermediateClassIvar" = global i64 32
-// CHECK: @"OBJC_IVAR_$_IntermediateClass.intermediateClassIvar2" = global i64 40
-// CHECK: @"OBJC_IVAR_$_IntermediateClass._intermediateProperty" = hidden global i64 48
-// CHECK: @"OBJC_IVAR_$_SubClass.subClassIvar" = global i64 56
-// CHECK: @"OBJC_IVAR_$_SubClass._subClassProperty" = hidden global i64 64
+// CHECK: @"OBJC_IVAR_$_IntermediateClass.intermediateClassIvar" = constant i64 32
+// CHECK: @"OBJC_IVAR_$_IntermediateClass.intermediateClassIvar2" = constant i64 40
+// CHECK: @"OBJC_IVAR_$_IntermediateClass._intermediateProperty" = hidden constant i64 48
+// CHECK: @"OBJC_IVAR_$_SubClass.subClassIvar" = constant i64 56
+// CHECK: @"OBJC_IVAR_$_SubClass._subClassProperty" = hidden constant i64 64
// CHECK: @"OBJC_IVAR_$_NotStaticLayout.not_static_layout_ivar" = hidden global i64 12
@interface NSObject {
@@ -24,6 +24,7 @@ @implementation StaticLayout {
-(void)meth {
static_layout_ivar = 0;
// CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_StaticLayout
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 20
}
@end
@@ -40,7 +41,7 @@ @implementation SuperClass {
- (void)superClassMethod {
_superClassProperty = 42;
superClassIvar = 10;
- // CHECK: load i64, ptr @"OBJC_IVAR_$_SuperClass
+ // CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_SuperClass
// CHECK: getelementptr inbounds i8, ptr %1, i64 20
}
@@ -67,8 +68,8 @@ @implementation IntermediateClass
@synthesize intermediateProperty = _intermediateProperty;
- (void)intermediateClassMethod {
intermediateClassIvar = 3.14;
- // CHECK: load i64, ptr @"OBJC_IVAR_$_IntermediateClass
- // CHECK: getelementptr inbounds i8, ptr %0, i64 %ivar
+ // CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_IntermediateClass
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 32
}
// CHECK-LABEL: define internal void @"\01-[IntermediateClass intermediateClassPropertyMethod]"
@@ -81,7 +82,8 @@ - (void)intermediateClassPropertyMethod {
// CHECK-LABEL: define internal void @"\01-[IntermediateClass intermediateClassPropertyMethodDirect]"
- (void)intermediateClassPropertyMethodDirect {
_intermediateProperty = 0;
- // CHECK: load i64, ptr @"OBJC_IVAR_$_IntermediateClass._intermediateProperty"
+ // CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_IntermediateClass._intermediateProperty"
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 48
}
@end
@@ -95,25 +97,26 @@ @interface SubClass : IntermediateClass
@implementation SubClass
// CHECK-LABEL: define internal void @"\01-[SubClass subclassVar]"
- (void)subclassVar {
-
subClassIvar = 6.28;
- // CHECK: load i64, ptr @"OBJC_IVAR_$_SubClass
- // CHECK: getelementptr inbounds i8, ptr %0, i64 %ivar
+ // CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_SubClass
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 56
}
// CHECK-LABEL: define internal void @"\01-[SubClass intermediateSubclassVar]"
-(void)intermediateSubclassVar {
intermediateClassIvar = 3.14;
- // CHECK: load i64, ptr @"OBJC_IVAR_$_IntermediateClass
- // CHECK: getelementptr inbounds i8, ptr %0, i64 %ivar
+ // CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_IntermediateClass
+ // CHECK: getelementptr inbounds i8, ptr %0, i64 32
}
// implicit synthesized method here:
// CHECK-LABEL: define internal ptr @"\01-[SubClass subClassProperty]"
-// CHECK: load i64, ptr @"OBJC_IVAR_$_SubClass._subClassProperty"
+// CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_SubClass._subClassProperty"
+// CHECK: getelementptr inbounds i8, ptr %0, i64 64
// CHECK-LABEL: define internal void @"\01-[SubClass setSubClassProperty:]"
-// CHECK: load i64, ptr @"OBJC_IVAR_$_SubClass._subClassProperty"
+// CHECK-NOT: load i64, ptr @"OBJC_IVAR_$_SubClass._subClassProperty"
+// CHECK: getelementptr inbounds i8, ptr %1, i64 64
@end
@interface NotNSObject {
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