Check alignment of loads when deciding whether it is safe to execute them

unconditionally.  Besides checking the offset, also check that the underlying
object is aligned as much as the load itself.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94875 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 6 deletions

diff --git a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 422ffd03a8..2d13298300 100644
--- a/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -200,14 +200,15 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) {
     //
     if (SelectInst *SI = dyn_cast<SelectInst>(Op)) {
       // load (select (Cond, &V1, &V2))  --> select(Cond, load &V1, load &V2).
-      if (isSafeToLoadUnconditionally(SI->getOperand(1), SI, TD) &&
-          isSafeToLoadUnconditionally(SI->getOperand(2), SI, TD)) {
+      unsigned Align = LI.getAlignment();
+      if (isSafeToLoadUnconditionally(SI->getOperand(1), SI, Align, TD) &&
+          isSafeToLoadUnconditionally(SI->getOperand(2), SI, Align, TD)) {
         LoadInst *V1 = Builder->CreateLoad(SI->getOperand(1),
-                                        SI->getOperand(1)->getName()+".val");
+                                           SI->getOperand(1)->getName()+".val");
         LoadInst *V2 = Builder->CreateLoad(SI->getOperand(2),
-                                        SI->getOperand(2)->getName()+".val");
-        V1->setAlignment(LI.getAlignment());
-        V2->setAlignment(LI.getAlignment());
+                                           SI->getOperand(2)->getName()+".val");
+        V1->setAlignment(Align);
+        V2->setAlignment(Align);
         return SelectInst::Create(SI->getCondition(), V1, V2);
       }