[ARM] Fix MVE ldst offset ranges

We were using isShiftedInt<7, Shift>(RHSC) to detect the ranges of offsets to
fold into MVE loads/stores. The instructions actually take a 7 bit unsigned
integer which is either added or subtracted. So something more like
isShiftedUInt<7, Shift>(abs(RHSC)).

Instead I've changes this to use the isScaledConstantInRange method, same as in
SelectT2AddrModeImm7Offset used by pre/post inc, which seemed to already be
getting this correct.

Differential revision: https://reviews.llvm.org/D66997

llvm-svn: 370731

1 files changed, 18 insertions, 19 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
index a3c7999f20f..9cdf2eb9c32 100644
--- a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -1282,32 +1282,31 @@ bool ARMDAGToDAGISel::SelectT2AddrModeImm8Offset(SDNode *Op, SDValue N,
   return false;
 }
 
-template<unsigned Shift>
-bool ARMDAGToDAGISel::SelectT2AddrModeImm7(SDValue N,
-                                           SDValue &Base, SDValue &OffImm) {
-  if (N.getOpcode() == ISD::SUB ||
-      CurDAG->isBaseWithConstantOffset(N)) {
-    if (auto RHS = dyn_cast<ConstantSDNode>(N.getOperand(1))) {
-      int RHSC = (int)RHS->getZExtValue();
-      if (N.getOpcode() == ISD::SUB)
-        RHSC = -RHSC;
-
-      if (isShiftedInt<7, Shift>(RHSC)) {
-        Base = N.getOperand(0);
-        if (Base.getOpcode() == ISD::FrameIndex) {
-          int FI = cast<FrameIndexSDNode>(Base)->getIndex();
-          Base = CurDAG->getTargetFrameIndex(
+template <unsigned Shift>
+bool ARMDAGToDAGISel::SelectT2AddrModeImm7(SDValue N, SDValue &Base,
+                                           SDValue &OffImm) {
+  if (N.getOpcode() == ISD::SUB || CurDAG->isBaseWithConstantOffset(N)) {
+    int RHSC;
+    if (isScaledConstantInRange(N.getOperand(1), 1 << Shift, -0x7f, 0x80,
+                                RHSC)) {
+      Base = N.getOperand(0);
+      if (Base.getOpcode() == ISD::FrameIndex) {
+        int FI = cast<FrameIndexSDNode>(Base)->getIndex();
+        Base = CurDAG->getTargetFrameIndex(
             FI, TLI->getPointerTy(CurDAG->getDataLayout()));
-        }
-        OffImm = CurDAG->getTargetConstant(RHSC, SDLoc(N), MVT::i32);
-        return true;
       }
+
+      if (N.getOpcode() == ISD::SUB)
+        RHSC = -RHSC;
+      OffImm =
+          CurDAG->getTargetConstant(RHSC * (1 << Shift), SDLoc(N), MVT::i32);
+      return true;
     }
   }
 
   // Base only.
   Base = N;
-  OffImm  = CurDAG->getTargetConstant(0, SDLoc(N), MVT::i32);
+  OffImm = CurDAG->getTargetConstant(0, SDLoc(N), MVT::i32);
   return true;
 }