Fix PR1657

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@42075 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LICM.cpp b/lib/Transforms/Scalar/LICM.cpp
index ac927da07e32a9fcf260846bef71d2fbec126c45..6c5976ad3a914837d92b8b3c9d309880c79c383d 100644 (file)
--- a/lib/Transforms/Scalar/LICM.cpp
+++ b/lib/Transforms/Scalar/LICM.cpp
@@ -791,6 +791,14 @@ void LICM::FindPromotableValuesInLoop(
           break;
         }
 
+      // If GEP base is NULL then the calculated address  used by Store or
+      // Load instruction is invalid. Do not promote this value because
+      // it may expose load and store instruction that are covered by
+      // condition which may not yet folded.
+      if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(V))
+        if (isa<ConstantPointerNull>(GEP->getOperand(0)))
+          PointerOk = false;
+
       if (PointerOk) {
         const Type *Ty = cast<PointerType>(V->getType())->getElementType();
         AllocaInst *AI = new AllocaInst(Ty, 0, V->getName()+".tmp", FnStart);

diff --git a/test/Transforms/LICM/2007-09-17-PrompteValue.ll b/test/Transforms/LICM/2007-09-17-PrompteValue.ll
new file mode 100644 (file)
index 0000000..acbbabf
--- /dev/null
+++ b/test/Transforms/LICM/2007-09-17-PrompteValue.ll
@@ -0,0 +1,26 @@
+; ModuleID = 'PR1657.bc'
+; Do not promote getelementptr because it may exposes load from a null pointer 
+; and store from a null pointer  which are covered by 
+; icmp eq %struct.decision* null, null condition.
+; RUN: llvm-as < %s | opt -licm | llvm-dis | not grep promoted
+       %struct.decision = type { i8, %struct.decision* }
+
+define i32 @main() {
+entry:
+       br label %blah.i
+
+blah.i:                ; preds = %cond_true.i, %entry
+       %tmp3.i = icmp eq %struct.decision* null, null          ; <i1> [#uses=1]
+       br i1 %tmp3.i, label %clear_modes.exit, label %cond_true.i
+
+cond_true.i:           ; preds = %blah.i
+       %tmp1.i = getelementptr %struct.decision* null, i32 0, i32 0            ; <i8*> [#uses=1]
+       store i8 0, i8* %tmp1.i
+       br label %blah.i
+
+clear_modes.exit:              ; preds = %blah.i
+       call void @exit( i32 0 )
+       unreachable
+}
+
+declare void @exit(i32)