[SystemZ] Prefer LHI;ST... over LAY;MV...

If we had a store of an integer to memory, and the integer and store size
were suitable for a form of MV..., we used MV... no matter what.  We could
then have sequences like:

    lay %r2, 0(%r3,%r4)
    mvi 0(%r2), 4

In these cases it seems better to force the constant into a register
and use a normal store:

    lhi %r2, 4
    stc %r2, 0(%r3, %r4)

since %r2 is more likely to be hoisted and is easier to rematerialize.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@189098 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 25 insertions, 0 deletions

diff --git a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
index d9794b1d64..e0d543791b 100644
--- a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
+++ b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
@@ -159,6 +159,12 @@ class SystemZDAGToDAGISel : public SelectionDAGISel {
   bool selectBDAddr(SystemZAddressingMode::DispRange DR, SDValue Addr,
                     SDValue &Base, SDValue &Disp);
 
+  // Try to match Addr as a FormBDX address with displacement type DR.
+  // Return true on success and if the result had no index.  Store the
+  // base and displacement in Base and Disp respectively.
+  bool selectMVIAddr(SystemZAddressingMode::DispRange DR, SDValue Addr,
+                     SDValue &Base, SDValue &Disp);
+
   // Try to match Addr as a FormBDX* address of form Form with
   // displacement type DR.  Return true on success, storing the base,
   // displacement and index in Base, Disp and Index respectively.
@@ -189,6 +195,14 @@ class SystemZDAGToDAGISel : public SelectionDAGISel {
     return selectBDAddr(SystemZAddressingMode::Disp20Pair, Addr, Base, Disp);
   }
 
+  // MVI matching routines used by SystemZOperands.td.
+  bool selectMVIAddr12Pair(SDValue Addr, SDValue &Base, SDValue &Disp) {
+    return selectMVIAddr(SystemZAddressingMode::Disp12Pair, Addr, Base, Disp);
+  }
+  bool selectMVIAddr20Pair(SDValue Addr, SDValue &Base, SDValue &Disp) {
+    return selectMVIAddr(SystemZAddressingMode::Disp20Pair, Addr, Base, Disp);
+  }
+
   // BDX matching routines used by SystemZOperands.td.
   bool selectBDXAddr12Only(SDValue Addr, SDValue &Base, SDValue &Disp,
                            SDValue &Index) {
@@ -575,6 +589,17 @@ bool SystemZDAGToDAGISel::selectBDAddr(SystemZAddressingMode::DispRange DR,
   return true;
 }
 
+bool SystemZDAGToDAGISel::selectMVIAddr(SystemZAddressingMode::DispRange DR,
+                                        SDValue Addr, SDValue &Base,
+                                        SDValue &Disp) {
+  SystemZAddressingMode AM(SystemZAddressingMode::FormBDXNormal, DR);
+  if (!selectAddress(Addr, AM) || AM.Index.getNode())
+    return false;
+
+  getAddressOperands(AM, Addr.getValueType(), Base, Disp);
+  return true;
+}
+
 bool SystemZDAGToDAGISel::selectBDXAddr(SystemZAddressingMode::AddrForm Form,
                                         SystemZAddressingMode::DispRange DR,
                                         SDValue Addr, SDValue &Base,