CastInst::castIsValid should return true if the dest type is the same as

Value's current type. The casting is trivial even for aggregate type.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@172143 91177308-0d34-0410-b5e6-96231b3b80d8

lib/IR/Instructions.cpp

@@ -2624,6 +2624,11 @@ CastInst::castIsValid(Instruction::CastOps op, Value *S, Type *DstTy) {
 
   // Check for type sanity on the arguments
   Type *SrcTy = S->getType();
+
+  // If this is a cast to the same type then it's trivially true.
+  if (SrcTy == DstTy)
+    return true;
+
   if (!SrcTy->isFirstClassType() || !DstTy->isFirstClassType() ||
       SrcTy->isAggregateType() || DstTy->isAggregateType())
     return false;

test/Transforms/MergeFunc/2013-01-10-MergeFuncAssert.ll

@@ -0,0 +1,36 @@
+; RUN: opt -mergefunc -disable-output < %s
+; This used to trigger a ConstantExpr::getBitCast assertion.
+
+define void @t1() unnamed_addr uwtable ssp align 2 {
+entry:
+  switch i32 undef, label %sw.bb12 [
+    i32 127, label %sw.bb
+    i32 126, label %sw.bb4
+  ]
+
+sw.bb:                                            ; preds = %entry
+  unreachable
+
+sw.bb4:                                           ; preds = %entry
+  unreachable
+
+sw.bb12:                                          ; preds = %entry
+  ret void
+}
+
+define void @t2() unnamed_addr uwtable ssp align 2 {
+entry:
+  switch i32 undef, label %sw.bb8 [
+    i32 4, label %sw.bb
+    i32 3, label %sw.bb4
+  ]
+
+sw.bb:                                            ; preds = %entry
+  unreachable
+
+sw.bb4:                                           ; preds = %entry
+  ret void
+
+sw.bb8:                                           ; preds = %entry
+  unreachable
+}