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

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index 3058f74aab900dcd0143ada6c5bf5d7c1b018ea8..f112ba8262063aaa4135afd4faea8e90bc73baa8 100644 (file)
--- 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 (file)
index 0000000..f9f45f3
--- /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)