Don't swap the operands of a subtraction when trying to create a

post-decrement load/store.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@81464 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 58f931234e1bd45cfebceeaff884585dde33ca67..8236ca404dfdaf64d0c4c21c280add92693ea528 100644 (file)
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -4715,7 +4715,7 @@ bool DAGCombiner::CombineToPostIndexedLoadStore(SDNode *N) {
     SDValue Offset;
     ISD::MemIndexedMode AM = ISD::UNINDEXED;
     if (TLI.getPostIndexedAddressParts(N, Op, BasePtr, Offset, AM, DAG)) {
-      if (Ptr == Offset)
+      if (Ptr == Offset && Op->getOpcode() == ISD::ADD)
         std::swap(BasePtr, Offset);
       if (Ptr != BasePtr)
         continue;

diff --git a/test/CodeGen/ARM/2009-09-10-postdec.ll b/test/CodeGen/ARM/2009-09-10-postdec.ll
new file mode 100644 (file)
index 0000000..10653b5
--- /dev/null
+++ b/test/CodeGen/ARM/2009-09-10-postdec.ll
@@ -0,0 +1,11 @@
+; RUN: llc -march=arm < %s | FileCheck %s
+; Radar 7213850
+
+define i32 @test(i8* %d, i32 %x, i32 %y) nounwind {
+  %1 = ptrtoint i8* %d to i32
+;CHECK: sub
+  %2 = sub i32 %x, %1
+  %3 = add nsw i32 %2, %y
+  store i8 0, i8* %d, align 1
+  ret i32 %3
+}