From 128459b85b59530e511ea17b3cc3a5b8ee3e8bd4 Mon Sep 17 00:00:00 2001
From: Devang Patel <dpatel@apple.com>
Date: Mon, 24 Sep 2007 20:02:42 +0000
Subject: [PATCH]  Do not promote null values because it may be unsafe to do
 so.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42270 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/LICM.cpp                |  4 ++
 .../LICM/2007-09-24-PromoteNullValue.ll       | 46 +++++++++++++++++++
 2 files changed, 50 insertions(+)
 create mode 100644 test/Transforms/LICM/2007-09-24-PromoteNullValue.ll

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 3058f74aab9..f112ba82620 100644
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -800,6 +800,10 @@ void LICM::FindPromotableValuesInLoop(
           break;
         }
 
+      // Do not promote null values because it may be unsafe to do so.
+      if (isa<ConstantPointerNull>(V))
+        PointerOk = false;
+
       if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V)) {
         // If GEP base is NULL then the calculated address used by Store or
         // Load instruction is invalid. Do not promote this value because
diff --git a/test/Transforms/LICM/2007-09-24-PromoteNullValue.ll b/test/Transforms/LICM/2007-09-24-PromoteNullValue.ll
new file mode 100644
index 00000000000..f9f45f389b8
--- /dev/null
+++ b/test/Transforms/LICM/2007-09-24-PromoteNullValue.ll
@@ -0,0 +1,46 @@
+; Do not promote null value because it may be unsafe to do so.
+; RUN: llvm-as < %s | opt -licm | llvm-dis | not grep promoted
+
+define i32 @f(i32 %foo, i32 %bar, i32 %com) {
+entry:
+	%tmp2 = icmp eq i32 %foo, 0		; <i1> [#uses=1]
+	br i1 %tmp2, label %cond_next, label %cond_true
+
+cond_true:		; preds = %entry
+	br label %return
+
+cond_next:		; preds = %entry
+	br label %bb
+
+bb:		; preds = %bb15, %cond_next
+	switch i32 %bar, label %bb15 [
+		 i32 1, label %bb6
+	]
+
+bb6:		; preds = %bb
+	%tmp8 = icmp eq i32 %com, 0		; <i1> [#uses=1]
+	br i1 %tmp8, label %cond_next14, label %cond_true11
+
+cond_true11:		; preds = %bb6
+	br label %return
+
+cond_next14:		; preds = %bb6
+	store i8 0, i8* null
+	br label %bb15
+
+bb15:		; preds = %cond_next14, %bb
+	br label %bb
+
+return:		; preds = %cond_true11, %cond_true
+	%storemerge = phi i32 [ 0, %cond_true ], [ undef, %cond_true11 ]		; <i32> [#uses=1]
+	ret i32 %storemerge
+}
+
+define i32 @kdMain() {
+entry:
+	%tmp1 = call i32 @f( i32 0, i32 1, i32 1 )		; <i32> [#uses=0]
+	call void @exit( i32 0 )
+	unreachable
+}
+
+declare void @exit(i32)
-- 
2.34.1