[llvm-commits] [llvm] r140815 - in /llvm/trunk: lib/Transforms/Scalar/ObjCARC.cpp test/Transforms/ObjCARC/empty-block.ll

Dan Gohman gohman at apple.com
Thu Sep 29 15:27:34 PDT 2011


Author: djg
Date: Thu Sep 29 17:27:34 2011
New Revision: 140815

URL: http://llvm.org/viewvc/llvm-project?rev=140815&view=rev
Log:
When eliminating unnecessary retain+autorelease on return values,
handle the case where the retain is in a different basic block.
rdar://10210274.

Added:
    llvm/trunk/test/Transforms/ObjCARC/empty-block.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp?rev=140815&r1=140814&r2=140815&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/ObjCARC.cpp Thu Sep 29 17:27:34 2011
@@ -3198,7 +3198,8 @@
 
         // Check that there is nothing that can affect the reference
         // count between the retain and the call.
-        FindDependencies(CanChangeRetainCount, Arg, BB, Retain,
+        // Note that Retain need not be in BB.
+        FindDependencies(CanChangeRetainCount, Arg, Retain->getParent(), Retain,
                          DependingInstructions, Visited, PA);
         if (DependingInstructions.size() != 1)
           goto next_block;

Added: llvm/trunk/test/Transforms/ObjCARC/empty-block.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ObjCARC/empty-block.ll?rev=140815&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/ObjCARC/empty-block.ll (added)
+++ llvm/trunk/test/Transforms/ObjCARC/empty-block.ll Thu Sep 29 17:27:34 2011
@@ -0,0 +1,59 @@
+; RUN: opt -S -objc-arc < %s | FileCheck %s
+; rdar://10210274
+
+%0 = type opaque
+
+declare i8* @objc_retain(i8*)
+
+declare void @objc_release(i8*)
+
+declare i8* @objc_autoreleaseReturnValue(i8*)
+
+; Don't delete the autorelease.
+
+; CHECK: define %0* @test0(
+; CHECK:   @objc_retain
+; CHECK: .lr.ph:
+; CHECK-NOT: @objc_r
+; CHECK: @objc_autoreleaseReturnValue
+; CHECK-NOT: @objc_
+; CHECK: }
+define %0* @test0(%0* %buffer) nounwind {
+  %1 = bitcast %0* %buffer to i8*
+  %2 = tail call i8* @objc_retain(i8* %1) nounwind
+  br i1 undef, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %.lr.ph, %0
+  br i1 false, label %.lr.ph, label %._crit_edge
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  %3 = tail call i8* @objc_retain(i8* %1) nounwind
+  tail call void @objc_release(i8* %1) nounwind, !clang.imprecise_release !0
+  %4 = tail call i8* @objc_autoreleaseReturnValue(i8* %1) nounwind
+  ret %0* %buffer
+}
+
+; Do delete the autorelease, even with the retain in a different block.
+
+; CHECK: define %0* @test1(
+; CHECK-NOT: @objc
+; CHECK: }
+define %0* @test1() nounwind {
+  %buffer = call %0* @foo()
+  %1 = bitcast %0* %buffer to i8*
+  %2 = tail call i8* @objc_retain(i8* %1) nounwind
+  br i1 undef, label %.lr.ph, label %._crit_edge
+
+.lr.ph:                                           ; preds = %.lr.ph, %0
+  br i1 false, label %.lr.ph, label %._crit_edge
+
+._crit_edge:                                      ; preds = %.lr.ph, %0
+  %3 = tail call i8* @objc_retain(i8* %1) nounwind
+  tail call void @objc_release(i8* %1) nounwind, !clang.imprecise_release !0
+  %4 = tail call i8* @objc_autoreleaseReturnValue(i8* %1) nounwind
+  ret %0* %buffer
+}
+
+declare %0* @foo()
+
+!0 = metadata !{}





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