[llvm] r316401 - ObjCARC: do not increment past the end of the BB

[Saleem Abdulrasool via llvm-commits]

Author: compnerd
Date: Mon Oct 23 17:09:10 2017
New Revision: 316401

URL: http://llvm.org/viewvc/llvm-project?rev=316401&view=rev
Log:
ObjCARC: do not increment past the end of the BB

The `BasicBlock::getFirstInsertionPt` call may return `std::end` for the
BB.  Dereferencing the end iterator results in an assertion failure
"(!NodePtr->isKnownSentinel()), function operator*".  Ensure that the
returned iterator is valid before dereferencing it.  If the end is
returned, move one position backward to get a valid insertion point.

Added:
    llvm/trunk/test/Transforms/ObjCARC/invoke-2.ll
Modified:
    llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp

Modified: llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp?rev=316401&r1=316400&r2=316401&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/PtrState.cpp Mon Oct 23 17:09:10 2017
@@ -250,10 +250,14 @@ void BottomUpPtrState::HandlePotentialUs
     // If this is an invoke instruction, we're scanning it as part of
     // one of its successor blocks, since we can't insert code after it
     // in its own block, and we don't want to split critical edges.
-    if (isa<InvokeInst>(Inst))
-      InsertReverseInsertPt(&*BB->getFirstInsertionPt());
-    else
-      InsertReverseInsertPt(&*++Inst->getIterator());
+    BasicBlock::iterator InsertAfter;
+    if (isa<InvokeInst>(Inst)) {
+      const auto IP = BB->getFirstInsertionPt();
+      InsertAfter = IP == BB->end() ? std::prev(BB->end()) : IP;
+    } else {
+      InsertAfter = std::next(Inst->getIterator());
+    }
+    InsertReverseInsertPt(&*InsertAfter);
   };
 
   // Check for possible direct uses.

Added: llvm/trunk/test/Transforms/ObjCARC/invoke-2.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ObjCARC/invoke-2.ll?rev=316401&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/ObjCARC/invoke-2.ll (added)
+++ llvm/trunk/test/Transforms/ObjCARC/invoke-2.ll Mon Oct 23 17:09:10 2017
@@ -0,0 +1,57 @@
+; RUN: opt -mtriple x86_64-unknown-windows-msvc -objc-arc -o - %s | llvm-dis -o - - | FileCheck %s
+
+target triple = "x86_64-unknown-windows-msvc"
+
+declare i32 @__CxxFrameHandler3(...)
+
+declare dllimport i8* @objc_msgSend(i8*, i8*, ...) local_unnamed_addr
+
+declare dllimport i8* @objc_retain(i8* returned) local_unnamed_addr
+declare dllimport void @objc_release(i8*) local_unnamed_addr
+declare dllimport i8* @objc_retainAutoreleasedReturnValue(i8* returned) local_unnamed_addr
+
+declare dllimport i8* @objc_begin_catch(i8*) local_unnamed_addr
+declare dllimport void @objc_end_catch() local_unnamed_addr
+
+ at OBJC_METH_VAR_NAME_ = private unnamed_addr constant [2 x i8] c"m\00", align 1
+ at OBJC_SELECTOR_REFERENCES_ = private externally_initialized global i8* getelementptr inbounds ([2 x i8], [2 x i8]* @OBJC_METH_VAR_NAME_, i64 0, i64 0), section ".objc_selrefs$B", align 8
+
+define void @f(i8* %i) local_unnamed_addr personality i8* bitcast (i32 (...)* @__CxxFrameHandler3 to i8*) {
+entry:
+  %0 = tail call i8* @objc_retain(i8* %i)
+  %1 = load i8*, i8** @OBJC_SELECTOR_REFERENCES_, align 8, !invariant.load !0
+  %call = invoke i8* bitcast (i8* (i8*, i8*, ...)* @objc_msgSend to i8* (i8*, i8*)*)(i8* %0, i8* %1)
+          to label %invoke.cont unwind label %catch.dispatch, !clang.arc.no_objc_arc_exceptions !0
+
+catch.dispatch:                                   ; preds = %entry
+  %2 = catchswitch within none [label %catch] unwind to caller
+
+invoke.cont:                                      ; preds = %entry
+  %3 = tail call i8* @objc_retainAutoreleasedReturnValue(i8* %call)
+  tail call void @objc_release(i8* %3) #0, !clang.imprecise_release !0
+  br label %eh.cont
+
+eh.cont:                                          ; preds = %invoke.cont, %catch
+  tail call void @objc_release(i8* %0) #0, !clang.imprecise_release !0
+  ret void
+
+catch:                                            ; preds = %catch.dispatch
+  %4 = catchpad within %2 [i8* null, i32 0, i8* null]
+  %exn.adjusted = tail call i8* @objc_begin_catch(i8* undef)
+  tail call void @objc_end_catch(), !clang.arc.no_objc_arc_exceptions !0
+  br label %eh.cont
+}
+
+; CHECK-LABEL: @f
+
+; CHECK-NOT: tail call i8* @objc_retain(i8* %i)
+; CHECK: load i8*, i8** @OBJC_SELECTOR_REFERENCES_, align 8
+
+; CHECK: eh.cont:
+; CHECK-NOT: call void @objc_release(i8*
+; CHECK: ret void
+
+attributes #0 = { nounwind }
+
+!0 = !{}
+