[clang] 45ffe63 - [clang/objc] Optimize getters for non-atomic, copied properties

[Nico Weber via cfe-commits]

Author: Dave MacLachlan
Date: 2021-07-13T09:22:13-04:00
New Revision: 45ffe6341d9642487785b0d0028166e6fbdbe5d7

URL: https://github.com/llvm/llvm-project/commit/45ffe6341d9642487785b0d0028166e6fbdbe5d7
DIFF: https://github.com/llvm/llvm-project/commit/45ffe6341d9642487785b0d0028166e6fbdbe5d7.diff

LOG: [clang/objc] Optimize getters for non-atomic, copied properties

Properties that were declared `@property(copy, nonatomic) id foo` make an
unnecessary call to objc_get_property().  This call can be replaced with a
direct access to the backing variable identical to how a `@property(nonatomic)
id foo` would do it.

This reduces codegen by 4 bytes (x86_64/arm64) and removes a cross linkage unit
function call per property declared as copy/nonatomic.

Differential Revision: https://reviews.llvm.org/D105311

Added: 
    

Modified: 
    clang/lib/CodeGen/CGObjC.cpp
    clang/test/CodeGenObjC/arc-blocks.m

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CGObjC.cpp b/clang/lib/CodeGen/CGObjC.cpp
index b865780ffe93c..2f0acd440e50d 100644
--- a/clang/lib/CodeGen/CGObjC.cpp
+++ b/clang/lib/CodeGen/CGObjC.cpp
@@ -925,10 +925,11 @@ PropertyImplStrategy::PropertyImplStrategy(CodeGenModule &CGM,
   IvarSize = TInfo.Width;
   IvarAlignment = TInfo.Align;
 
-  // If we have a copy property, we always have to use getProperty/setProperty.
-  // TODO: we could actually use setProperty and an expression for non-atomics.
+  // If we have a copy property, we always have to use setProperty.
+  // If the property is atomic we need to use getProperty, but in
+  // the nonatomic case we can just use expression.
   if (IsCopy) {
-    Kind = GetSetProperty;
+    Kind = IsAtomic ? GetSetProperty : SetPropertyAndExpressionGet;
     return;
   }
 

diff  --git a/clang/test/CodeGenObjC/arc-blocks.m b/clang/test/CodeGenObjC/arc-blocks.m
index 078408bc1d6c0..ab0ee3789cba8 100644
--- a/clang/test/CodeGenObjC/arc-blocks.m
+++ b/clang/test/CodeGenObjC/arc-blocks.m
@@ -477,7 +477,7 @@ @implementation Test12
 // CHECK:    call void @objc_setProperty(i8* {{%.*}}, i8* {{%.*}}, i64 {{%.*}}, i8* {{%.*}}, i1 zeroext true, i1 zeroext true)
 
 // CHECK:    define internal void ()* @"\01-[Test12 nblock]"(
-// CHECK:    call i8* @objc_getProperty(i8* {{%.*}}, i8* {{%.*}}, i64 {{%.*}}, i1 zeroext false)
+// CHECK:    %add.ptr = getelementptr inbounds i8, i8* %1, i64 %ivar
 
 // CHECK:    define internal void @"\01-[Test12 setNblock:]"(
 // CHECK:    call void @objc_setProperty(i8* {{%.*}}, i8* {{%.*}}, i64 {{%.*}}, i8* {{%.*}}, i1 zeroext false, i1 zeroext true)