From 11745d4c0276ccb5c64f83d6954b54c8ff2aec98 Mon Sep 17 00:00:00 2001
From: Andrew Trick <atrick@apple.com>
Date: Wed, 29 Jun 2011 03:13:40 +0000
Subject: [PATCH] indvars -disable-iv-rewrite: just because SCEV ignores casts
 doesn't mean they can be removed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134054 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/IndVarSimplify.cpp      |  1 +
 .../IndVarSimplify/no-iv-rewrite.ll           | 37 +++++++++++++++++++
 2 files changed, 38 insertions(+)

diff --git a/lib/Transforms/Scalar/IndVarSimplify.cpp b/lib/Transforms/Scalar/IndVarSimplify.cpp
index 8986dbb7858..919da3587a1 100644
--- a/lib/Transforms/Scalar/IndVarSimplify.cpp
+++ b/lib/Transforms/Scalar/IndVarSimplify.cpp
@@ -1007,6 +1007,7 @@ bool IndVarSimplify::EliminateIVUser(Instruction *UseInst,
 
   // Eliminate any operation that SCEV can prove is an identity function.
   if (!SE->isSCEVable(UseInst->getType()) ||
+      (UseInst->getType() != IVOperand->getType()) ||
       (SE->getSCEV(UseInst) != SE->getSCEV(IVOperand)))
     return false;
 
diff --git a/test/Transforms/IndVarSimplify/no-iv-rewrite.ll b/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
index c35feef26f9..462ff582565 100644
--- a/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
+++ b/test/Transforms/IndVarSimplify/no-iv-rewrite.ll
@@ -23,6 +23,7 @@ ph:
 ; sext should be eliminated while preserving gep inboundsness.
 ; CHECK-NOT: sext
 ; CHECK: getelementptr inbounds
+; CHECK: exit
 loop:
   %i.02 = phi i32 [ 0, %ph ], [ %iinc, %loop ]
   %s.01 = phi i32 [ 0, %ph ], [ %sinc, %loop ]
@@ -63,6 +64,7 @@ ph:
 ; CHECK: getelementptr inbounds
 ; %vall sext should obviously not be eliminated
 ; CHECK: sext
+; CHECK: exit
 loop:
   %i.02 = phi i32 [ 0, %ph ], [ %iinc, %loop ]
   %s.01 = phi i64 [ 0, %ph ], [ %sinc, %loop ]
@@ -106,6 +108,7 @@ ph:
 ; Preserve gep inboundsness, and don't factor it.
 ; CHECK: getelementptr inbounds i32* %ptriv, i32 1
 ; CHECK-NOT: add
+; CHECK: exit
 loop:
   %ptriv = phi i32* [ %first, %ph ], [ %ptrpost, %loop ]
   %ofs = sext i32 %idx to i64
@@ -121,3 +124,37 @@ exit:
 return:
   ret void
 }
+
+%struct = type { i32 }
+
+define void @bitcastiv(i32 %start, i32 %limit, i32 %step, %struct* %base)
+nounwind
+{
+entry:
+  br label %loop
+
+; CHECK: loop:
+;
+; Preserve casts
+; CHECK: phi i32
+; CHECK: bitcast
+; CHECK: getelementptr
+; CHECK: exit
+loop:
+  %iv = phi i32 [%start, %entry], [%next, %loop]
+  %p = phi %struct* [%base, %entry], [%pinc, %loop]
+  %adr = getelementptr %struct* %p, i32 0, i32 0
+  store i32 3, i32* %adr
+  %pp = bitcast %struct* %p to i32*
+  store i32 4, i32* %pp
+  %pinc = getelementptr %struct* %p, i32 1
+  %next = add i32 %iv, 1
+  %cond = icmp ne i32 %next, %limit
+  br i1 %cond, label %loop, label %exit
+
+exit:
+  br label %return
+
+return:
+  ret void
+}
\ No newline at end of file