At -O0, prefer objc_storeStrong with a null new value to the
combination of a load+objc_release; this is generally better
for tools that try to track why values are retained and
released. Also use objc_storeStrong when copying a block
(again, only at -O0), which requires us to do a preliminary
store of null in order to compensate for objc_storeStrong's
assign semantics.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@166085 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index 0fa70e7..a47c56f 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -1949,6 +1949,28 @@
}
}
+/// Destroy a __strong variable.
+///
+/// At -O0, emit a call to store 'null' into the address;
+/// instrumenting tools prefer this because the address is exposed,
+/// but it's relatively cumbersome to optimize.
+///
+/// At -O1 and above, just load and call objc_release.
+///
+/// call void \@objc_storeStrong(i8** %addr, i8* null)
+void CodeGenFunction::EmitARCDestroyStrong(llvm::Value *addr, bool precise) {
+ if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
+ llvm::PointerType *addrTy = cast<llvm::PointerType>(addr->getType());
+ llvm::Value *null = llvm::ConstantPointerNull::get(
+ cast<llvm::PointerType>(addrTy->getElementType()));
+ EmitARCStoreStrongCall(addr, null, /*ignored*/ true);
+ return;
+ }
+
+ llvm::Value *value = Builder.CreateLoad(addr);
+ EmitARCRelease(value, precise);
+}
+
/// Store into a strong object. Always calls this:
/// call void \@objc_storeStrong(i8** %addr, i8* %value)
llvm::Value *CodeGenFunction::EmitARCStoreStrongCall(llvm::Value *addr,
@@ -2222,15 +2244,13 @@
void CodeGenFunction::destroyARCStrongPrecise(CodeGenFunction &CGF,
llvm::Value *addr,
QualType type) {
- llvm::Value *ptr = CGF.Builder.CreateLoad(addr, "strongdestroy");
- CGF.EmitARCRelease(ptr, /*precise*/ true);
+ CGF.EmitARCDestroyStrong(addr, /*precise*/ true);
}
void CodeGenFunction::destroyARCStrongImprecise(CodeGenFunction &CGF,
llvm::Value *addr,
QualType type) {
- llvm::Value *ptr = CGF.Builder.CreateLoad(addr, "strongdestroy");
- CGF.EmitARCRelease(ptr, /*precise*/ false);
+ CGF.EmitARCDestroyStrong(addr, /*precise*/ false);
}
void CodeGenFunction::destroyARCWeak(CodeGenFunction &CGF,