commit 5b07e8077a20b80fee90bd76c43c6150c676e4a8
author John McCall <rjmccall@apple.com> Wed Mar 13 03:10:54 2013 +0000
committer John McCall <rjmccall@apple.com> Wed Mar 13 03:10:54 2013 +0000
tree 6f93262867be60a728d721269a95eacee6c023ae
parent 365bc037d67220dae412b45281f04a96140168da

Tighten up the rules for precise lifetime and document
the requirements on the ARC optimizer.

rdar://13407451

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@176924 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CGObjC.cpp

diff --git a/lib/CodeGen/CGObjC.cpp b/lib/CodeGen/CGObjC.cpp
index ad7d629..f53f2a9 100644
--- a/lib/CodeGen/CGObjC.cpp
+++ b/lib/CodeGen/CGObjC.cpp
@@ -1686,7 +1686,8 @@
     llvm::Value *object;
 
     void Emit(CodeGenFunction &CGF, Flags flags) {
-      CGF.EmitARCRelease(object, /*precise*/ true);
+      // Releases at the end of the full-expression are imprecise.
+      CGF.EmitARCRelease(object, ARCImpreciseLifetime);
     }
   };
 }
@@ -1940,7 +1941,8 @@
 
 /// Release the given object.
 ///   call void \@objc_release(i8* %value)
-void CodeGenFunction::EmitARCRelease(llvm::Value *value, bool precise) {
+void CodeGenFunction::EmitARCRelease(llvm::Value *value,
+                                     ARCPreciseLifetime_t precise) {
   if (isa<llvm::ConstantPointerNull>(value)) return;
 
   llvm::Constant *&fn = CGM.getARCEntrypoints().objc_release;
@@ -1956,7 +1958,7 @@
   // Call objc_release.
   llvm::CallInst *call = EmitNounwindRuntimeCall(fn, value);
 
-  if (!precise) {
+  if (precise == ARCImpreciseLifetime) {
     SmallVector<llvm::Value*,1> args;
     call->setMetadata("clang.imprecise_release",
                       llvm::MDNode::get(Builder.getContext(), args));
@@ -1972,7 +1974,8 @@
 /// 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) {
+void CodeGenFunction::EmitARCDestroyStrong(llvm::Value *addr,
+                                           ARCPreciseLifetime_t precise) {
   if (CGM.getCodeGenOpts().OptimizationLevel == 0) {
     llvm::PointerType *addrTy = cast<llvm::PointerType>(addr->getType());
     llvm::Value *null = llvm::ConstantPointerNull::get(
@@ -2042,7 +2045,7 @@
   EmitStoreOfScalar(newValue, dst);
 
   // Finally, release the old value.
-  EmitARCRelease(oldValue, /*precise*/ false);
+  EmitARCRelease(oldValue, dst.isARCPreciseLifetime());
 
   return newValue;
 }
@@ -2254,13 +2257,13 @@
 void CodeGenFunction::destroyARCStrongPrecise(CodeGenFunction &CGF,
                                               llvm::Value *addr,
                                               QualType type) {
-  CGF.EmitARCDestroyStrong(addr, /*precise*/ true);
+  CGF.EmitARCDestroyStrong(addr, ARCPreciseLifetime);
 }
 
 void CodeGenFunction::destroyARCStrongImprecise(CodeGenFunction &CGF,
                                                 llvm::Value *addr,
                                                 QualType type) {
-  CGF.EmitARCDestroyStrong(addr, /*precise*/ false);
+  CGF.EmitARCDestroyStrong(addr, ARCImpreciseLifetime);
 }
 
 void CodeGenFunction::destroyARCWeak(CodeGenFunction &CGF,
@@ -2737,7 +2740,7 @@
     llvm::Value *oldValue =
       EmitLoadOfScalar(lvalue);
     EmitStoreOfScalar(value, lvalue);
-    EmitARCRelease(oldValue, /*precise*/ false);
+    EmitARCRelease(oldValue, lvalue.isARCPreciseLifetime());
   } else {
     value = EmitARCStoreStrong(lvalue, value, ignored);
   }