Fix PR2471, which is a bug involving an invalid promotion from a conditional load.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52525 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 23 insertions, 1 deletions

diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp
index 72a27f5..54e611d 100644
--- a/lib/Transforms/Scalar/InstructionCombining.cpp
+++ b/lib/Transforms/Scalar/InstructionCombining.cpp
@@ -10062,10 +10062,16 @@ static bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom) {
   while (BBI != E) {
     --BBI;
 
+    // If we see a free or a call (which might do a free) the pointer could be
+    // marked invalid.
+    if (isa<FreeInst>(BBI) || isa<CallInst>(BBI))
+      return false;
+    
     if (LoadInst *LI = dyn_cast<LoadInst>(BBI)) {
       if (LI->getOperand(0) == V) return true;
-    } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI))
+    } else if (StoreInst *SI = dyn_cast<StoreInst>(BBI)) {
       if (SI->getOperand(1) == V) return true;
+    }
 
   }
   return false;
diff --git a/test/Transforms/InstCombine/2008-06-19-UncondLoad.ll b/test/Transforms/InstCombine/2008-06-19-UncondLoad.ll
new file mode 100644
index 0000000..fa3dc0a
--- /dev/null
+++ b/test/Transforms/InstCombine/2008-06-19-UncondLoad.ll
@@ -0,0 +1,16 @@
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep load | count 3
+; PR2471
+
+declare i32 @x(i32*)
+define i32 @b(i32* %a, i32* %b) {
+entry:
+        %tmp1 = load i32* %a            
+        %tmp3 = load i32* %b           
+        %add = add i32 %tmp1, %tmp3   
+        %call = call i32 @x( i32* %a )
+        %tobool = icmp ne i32 %add, 0
+	; not safe to turn into an uncond load
+        %cond = select i1 %tobool, i32* %b, i32* %a             
+        %tmp8 = load i32* %cond       
+        ret i32 %tmp8
+}