[ARM] Reorganise and simplify thumb-1 load/store selection

Other than PC-relative loads/store the patterns that match the various
load/store addressing modes have the same complexity, so the order that they
are matched is the order that they appear in the .td file.

Rearrange the instruction definitions in ARMInstrThumb.td, and make use of
AddedComplexity for PC-relative loads, so that the instruction matching order
is the order that results in the simplest selection logic. This also makes
register-offset load/store be selected when it should, as previously it was
only selected for too-large immediate offsets.

Differential Revision: http://reviews.llvm.org/D11800

llvm-svn: 244882

1 files changed, 6 insertions, 93 deletions

diff --git a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
index 541944c59bf..b8304423967 100644
--- a/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
+++ b/llvm/lib/Target/ARM/ARMISelDAGToDAG.cpp
@@ -160,11 +160,6 @@ public:
 
   // Thumb Addressing Modes:
   bool SelectThumbAddrModeRR(SDValue N, SDValue &Base, SDValue &Offset);
-  bool SelectThumbAddrModeRI(SDValue N, SDValue &Base, SDValue &Offset,
-                             unsigned Scale);
-  bool SelectThumbAddrModeRI5S1(SDValue N, SDValue &Base, SDValue &Offset);
-  bool SelectThumbAddrModeRI5S2(SDValue N, SDValue &Base, SDValue &Offset);
-  bool SelectThumbAddrModeRI5S4(SDValue N, SDValue &Base, SDValue &Offset);
   bool SelectThumbAddrModeImm5S(SDValue N, unsigned Scale, SDValue &Base,
                                 SDValue &OffImm);
   bool SelectThumbAddrModeImm5S1(SDValue N, SDValue &Base,
@@ -1086,77 +1081,13 @@ bool ARMDAGToDAGISel::SelectThumbAddrModeRR(SDValue N,
 }
 
 bool
-ARMDAGToDAGISel::SelectThumbAddrModeRI(SDValue N, SDValue &Base,
-                                       SDValue &Offset, unsigned Scale) {
-  if (Scale == 4) {
-    SDValue TmpBase, TmpOffImm;
-    if (SelectThumbAddrModeSP(N, TmpBase, TmpOffImm))
-      return false;  // We want to select tLDRspi / tSTRspi instead.
-
-    if (N.getOpcode() == ARMISD::Wrapper &&
-        N.getOperand(0).getOpcode() == ISD::TargetConstantPool)
-      return false;  // We want to select tLDRpci instead.
-  }
-
-  if (!CurDAG->isBaseWithConstantOffset(N))
-    return false;
-
-  // Thumb does not have [sp, r] address mode.
-  RegisterSDNode *LHSR = dyn_cast<RegisterSDNode>(N.getOperand(0));
-  RegisterSDNode *RHSR = dyn_cast<RegisterSDNode>(N.getOperand(1));
-  if ((LHSR && LHSR->getReg() == ARM::SP) ||
-      (RHSR && RHSR->getReg() == ARM::SP))
-    return false;
-
-  // FIXME: Why do we explicitly check for a match here and then return false?
-  // Presumably to allow something else to match, but shouldn't this be
-  // documented?
-  int RHSC;
-  if (isScaledConstantInRange(N.getOperand(1), Scale, 0, 32, RHSC))
-    return false;
-
-  Base = N.getOperand(0);
-  Offset = N.getOperand(1);
-  return true;
-}
-
-bool
-ARMDAGToDAGISel::SelectThumbAddrModeRI5S1(SDValue N,
-                                          SDValue &Base,
-                                          SDValue &Offset) {
-  return SelectThumbAddrModeRI(N, Base, Offset, 1);
-}
-
-bool
-ARMDAGToDAGISel::SelectThumbAddrModeRI5S2(SDValue N,
-                                          SDValue &Base,
-                                          SDValue &Offset) {
-  return SelectThumbAddrModeRI(N, Base, Offset, 2);
-}
-
-bool
-ARMDAGToDAGISel::SelectThumbAddrModeRI5S4(SDValue N,
-                                          SDValue &Base,
-                                          SDValue &Offset) {
-  return SelectThumbAddrModeRI(N, Base, Offset, 4);
-}
-
-bool
 ARMDAGToDAGISel::SelectThumbAddrModeImm5S(SDValue N, unsigned Scale,
                                           SDValue &Base, SDValue &OffImm) {
-  if (Scale == 4) {
-    SDValue TmpBase, TmpOffImm;
-    if (SelectThumbAddrModeSP(N, TmpBase, TmpOffImm))
-      return false;  // We want to select tLDRspi / tSTRspi instead.
-
-    if (N.getOpcode() == ARMISD::Wrapper &&
-        N.getOperand(0).getOpcode() == ISD::TargetConstantPool)
-      return false;  // We want to select tLDRpci instead.
-  }
-
   if (!CurDAG->isBaseWithConstantOffset(N)) {
-    if (N.getOpcode() == ARMISD::Wrapper &&
-        N.getOperand(0).getOpcode() != ISD::TargetGlobalAddress) {
+    if (N.getOpcode() == ISD::ADD) {
+      return false; // We want to select register offset instead
+    } else if (N.getOpcode() == ARMISD::Wrapper &&
+               N.getOperand(0).getOpcode() != ISD::TargetGlobalAddress) {
       Base = N.getOperand(0);
     } else {
       Base = N;
@@ -1166,23 +1097,6 @@ ARMDAGToDAGISel::SelectThumbAddrModeImm5S(SDValue N, unsigned Scale,
     return true;
   }
 
-  RegisterSDNode *LHSR = dyn_cast<RegisterSDNode>(N.getOperand(0));
-  RegisterSDNode *RHSR = dyn_cast<RegisterSDNode>(N.getOperand(1));
-  if ((LHSR && LHSR->getReg() == ARM::SP) ||
-      (RHSR && RHSR->getReg() == ARM::SP)) {
-    ConstantSDNode *LHS = dyn_cast<ConstantSDNode>(N.getOperand(0));
-    ConstantSDNode *RHS = dyn_cast<ConstantSDNode>(N.getOperand(1));
-    unsigned LHSC = LHS ? LHS->getZExtValue() : 0;
-    unsigned RHSC = RHS ? RHS->getZExtValue() : 0;
-
-    // Thumb does not have [sp, #imm5] address mode for non-zero imm5.
-    if (LHSC != 0 || RHSC != 0) return false;
-
-    Base = N;
-    OffImm = CurDAG->getTargetConstant(0, SDLoc(N), MVT::i32);
-    return true;
-  }
-
   // If the RHS is + imm5 * scale, fold into addr mode.
   int RHSC;
   if (isScaledConstantInRange(N.getOperand(1), Scale, 0, 32, RHSC)) {
@@ -1191,9 +1105,8 @@ ARMDAGToDAGISel::SelectThumbAddrModeImm5S(SDValue N, unsigned Scale,
     return true;
   }
 
-  Base = N.getOperand(0);
-  OffImm = CurDAG->getTargetConstant(0, SDLoc(N), MVT::i32);
-  return true;
+  // Offset is too large, so use register offset instead.
+  return false;
 }
 
 bool