Fix this assert. IP can point to an instruction with strange dominance

properties (invoke). Just assert that the instruction we return dominates
the insertion point.

llvm-svn: 151511

llvm/lib/Analysis/ScalarEvolutionExpander.cpp

@@ -34,16 +34,15 @@ Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
   // This function must be called with the builder having a valid insertion
   // point. It doesn't need to be the actual IP where the uses of the returned
   // cast will be added, but it must dominate such IP.
-  // We use this precondition to assert that we can produce a cast that will
+  // We use this precondition to produce a cast that will dominate all its
-  // dominate all its uses. In particular, this is crucial for the case
+  // uses. In particular, this is crucial for the case where the builder's
-  // where the builder's insertion point *is* the point where we were asked
+  // insertion point *is* the point where we were asked to put the cast.
-  // to put the cast.
   // Since we don't know the the builder's insertion point is actually
   // where the uses will be added (only that it dominates it), we are
   // not allowed to move it.
   BasicBlock::iterator BIP = Builder.GetInsertPoint();
 
-  assert(BIP == IP || SE.DT->dominates(IP, BIP));
+  Instruction *Ret = NULL;
 
   // Check to see if there is already a cast!
   for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
@@ -59,22 +58,28 @@ Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
             // Create a new cast, and leave the old cast in place in case
             // it is being used as an insert point. Clear its operand
             // so that it doesn't hold anything live.
-            Instruction *NewCI = CastInst::Create(Op, V, Ty, "", IP);
+            Ret = CastInst::Create(Op, V, Ty, "", IP);
-            NewCI->takeName(CI);
+            Ret->takeName(CI);
-            CI->replaceAllUsesWith(NewCI);
+            CI->replaceAllUsesWith(Ret);
             CI->setOperand(0, UndefValue::get(V->getType()));
-            rememberInstruction(NewCI);
+            break;
-            return NewCI;
           }
-          rememberInstruction(CI);
+          Ret = CI;
-          return CI;
+          break;
         }
   }
 
   // Create a new cast.
-  Instruction *I = CastInst::Create(Op, V, Ty, V->getName(), IP);
+  if (!Ret)
-  rememberInstruction(I);
+    Ret = CastInst::Create(Op, V, Ty, V->getName(), IP);
-  return I;
+
+  // We assert at the end of the function since IP might point to an
+  // instruction with different dominance properties than a cast
+  // (an invoke for example) and not dominate BIP (but the cast does).
+  assert(SE.DT->dominates(Ret, BIP));
+
+  rememberInstruction(Ret);
+  return Ret;
 }
 
 /// InsertNoopCastOfTo - Insert a cast of V to the specified type,

llvm/test/Transforms/LoopStrengthReduce/dominate-assert.ll

@@ -38,3 +38,33 @@ bb8:
 bb9:
   resume { i8*, i32 } zeroinitializer
 }
+
+
+define void @h() {
+bb1:
+  invoke void @g() optsize
+          to label %bb2 unwind label %bb5
+bb2:
+  %arrayctor.cur = phi i8* [ undef, %bb1 ], [ %arrayctor.next, %bb3 ]
+  invoke void @g() optsize
+          to label %bb3 unwind label %bb6
+bb3:
+  %arrayctor.next = getelementptr inbounds i8* %arrayctor.cur, i64 1
+  br label %bb2
+bb4:
+  ret void
+bb5:
+  %tmp = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
+          cleanup
+  invoke void @g() optsize
+          to label %bb4 unwind label %bb7
+bb6:
+  %tmp1 = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
+          cleanup
+  %arraydestroy.isempty = icmp eq i8* undef, %arrayctor.cur
+  ret void
+bb7:
+  %lpad.nonloopexit = landingpad { i8*, i32 } personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*)
+          catch i8* null
+  ret void
+}