[RISCV] Pattern-match frameindex

[s-barannikov]

No description provided.

[llvmbot]

@llvm/pr-subscribers-backend-risc-v

Author: Sergei Barannikov (s-barannikov)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/120917.diff

5 Files Affected:

• (modified) llvm/include/llvm/Target/GenericOpcodes.td (+1-1)
• (modified) llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp (+10-8)
• (modified) llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp (-23)
• (modified) llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h (-1)
• (modified) llvm/lib/Target/RISCV/RISCVInstrInfo.td (+13-5)

diff --git a/llvm/include/llvm/Target/GenericOpcodes.td b/llvm/include/llvm/Target/GenericOpcodes.td
index c8f91cd0de5978..e134bab61bf63c 100644
--- a/llvm/include/llvm/Target/GenericOpcodes.td
+++ b/llvm/include/llvm/Target/GenericOpcodes.td
@@ -99,7 +99,7 @@ def G_PHI : GenericInstruction {
 }
 
 def G_FRAME_INDEX : GenericInstruction {
-  let OutOperandList = (outs type0:$dst);
+  let OutOperandList = (outs ptype0:$dst);
   let InOperandList = (ins unknown:$src2);
   let hasSideEffects = false;
 }
diff --git a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
index 5aa66b3780b86b..ef85057ba1264d 100644
--- a/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
+++ b/llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp
@@ -131,6 +131,8 @@ class RISCVInstructionSelector : public InstructionSelector {
                       int OpIdx) const;
   void renderImm(MachineInstrBuilder &MIB, const MachineInstr &MI,
                  int OpIdx) const;
+  void renderFrameIndex(MachineInstrBuilder &MIB, const MachineInstr &MI,
+                        int OpIdx) const;
 
   void renderTrailingZeros(MachineInstrBuilder &MIB, const MachineInstr &MI,
                            int OpIdx) const;
@@ -715,14 +717,6 @@ bool RISCVInstructionSelector::select(MachineInstr &MI) {
     MI.setDesc(TII.get(RISCV::PseudoBRIND));
     MI.addOperand(MachineOperand::CreateImm(0));
     return constrainSelectedInstRegOperands(MI, TII, TRI, RBI);
-  case TargetOpcode::G_FRAME_INDEX: {
-    // TODO: We may want to replace this code with the SelectionDAG patterns,
-    // which fail to get imported because it uses FrameAddrRegImm, which is a
-    // ComplexPattern
-    MI.setDesc(TII.get(RISCV::ADDI));
-    MI.addOperand(MachineOperand::CreateImm(0));
-    return constrainSelectedInstRegOperands(MI, TII, TRI, RBI);
-  }
   case TargetOpcode::G_SELECT:
     return selectSelect(MI, MIB);
   case TargetOpcode::G_FCMP:
@@ -859,6 +853,14 @@ void RISCVInstructionSelector::renderImm(MachineInstrBuilder &MIB,
   MIB.addImm(CstVal);
 }
 
+void RISCVInstructionSelector::renderFrameIndex(MachineInstrBuilder &MIB,
+                                                const MachineInstr &MI,
+                                                int OpIdx) const {
+  assert(MI.getOpcode() == TargetOpcode::G_FRAME_INDEX && OpIdx == -1 &&
+         "Expected G_FRAME_INDEX");
+  MIB.add(MI.getOperand(1));
+}
+
 void RISCVInstructionSelector::renderTrailingZeros(MachineInstrBuilder &MIB,
                                                    const MachineInstr &MI,
                                                    int OpIdx) const {
diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
index b33d58d177457e..0070fd4520429f 100644
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.cpp
@@ -2531,29 +2531,6 @@ bool RISCVDAGToDAGISel::SelectAddrFrameIndex(SDValue Addr, SDValue &Base,
   return false;
 }
 
-// Select a frame index and an optional immediate offset from an ADD or OR.
-bool RISCVDAGToDAGISel::SelectFrameAddrRegImm(SDValue Addr, SDValue &Base,
-                                              SDValue &Offset) {
-  if (SelectAddrFrameIndex(Addr, Base, Offset))
-    return true;
-
-  if (!CurDAG->isBaseWithConstantOffset(Addr))
-    return false;
-
-  if (auto *FIN = dyn_cast<FrameIndexSDNode>(Addr.getOperand(0))) {
-    int64_t CVal = cast<ConstantSDNode>(Addr.getOperand(1))->getSExtValue();
-    if (isInt<12>(CVal)) {
-      Base = CurDAG->getTargetFrameIndex(FIN->getIndex(),
-                                         Subtarget->getXLenVT());
-      Offset = CurDAG->getSignedTargetConstant(CVal, SDLoc(Addr),
-                                               Subtarget->getXLenVT());
-      return true;
-    }
-  }
-
-  return false;
-}
-
 // Fold constant addresses.
 static bool selectConstantAddr(SelectionDAG *CurDAG, const SDLoc &DL,
                                const MVT VT, const RISCVSubtarget *Subtarget,
diff --git a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h
index e75aff7eda9938..592f517358506b 100644
--- a/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h
+++ b/llvm/lib/Target/RISCV/RISCVISelDAGToDAG.h
@@ -46,7 +46,6 @@ class RISCVDAGToDAGISel : public SelectionDAGISel {
                                     std::vector<SDValue> &OutOps) override;
 
   bool SelectAddrFrameIndex(SDValue Addr, SDValue &Base, SDValue &Offset);
-  bool SelectFrameAddrRegImm(SDValue Addr, SDValue &Base, SDValue &Offset);
   bool SelectAddrRegImm(SDValue Addr, SDValue &Base, SDValue &Offset,
                         bool IsRV32Zdinx = false);
   bool SelectAddrRegImmRV32Zdinx(SDValue Addr, SDValue &Base, SDValue &Offset) {
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.td b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
index af3ab88f700bff..833051374bab80 100644
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -400,9 +400,6 @@ def uimm6gt32 : ImmLeaf<XLenVT, [{
 }]>;
 
 // Addressing modes.
-// Necessary because a frameindex can't be matched directly in a pattern.
-def FrameAddrRegImm : ComplexPattern<iPTR, 2, "SelectFrameAddrRegImm",
-                                     [frameindex, or, add]>;
 def AddrRegImm : ComplexPattern<iPTR, 2, "SelectAddrRegImm">;
 
 // Return the negation of an immediate value.
@@ -1400,8 +1397,19 @@ def PseudoAddTPRel : Pseudo<(outs GPR:$rd),
 
 /// FrameIndex calculations
 
-def : Pat<(FrameAddrRegImm (iPTR GPR:$rs1), simm12:$imm12),
-          (ADDI GPR:$rs1, simm12:$imm12)>;
+// Converts frameindex -> tframeindex.
+def to_tframeindex : SDNodeXForm<frameindex, [{
+  return CurDAG->getTargetFrameIndex(N->getIndex(), N->getValueType(0));
+}]>;
+
+def : GICustomOperandRenderer<"renderFrameIndex">,
+      GISDNodeXFormEquiv<to_tframeindex>;
+
+def : Pat<(frameindex:$fi), (ADDI (iPTR (to_tframeindex $fi)), 0)>;
+
+def : Pat<(add_like frameindex:$fi, simm12:$offset),
+          (ADDI (iPTR (to_tframeindex $fi)), simm12:$offset)>;
+
 def GIAddrRegImm :
   GIComplexOperandMatcher<s32, "selectAddrRegImm">,
   GIComplexPatternEquiv<AddrRegImm>;

[topperc]

I think add_like might be less capable than SelectionDAG::isBaseWithConstantOffset, but if it shows up its probably fixable.

[s-barannikov]

isBaseWithConstantOffset additionally handles (xor x, INT_MIN), that's all the difference I noticed.

[lenary]

Given you think there is a difference, please don't mark this as "NFCI" in the message.

[s-barannikov]

I removed NFCI now

[topperc]

LGTM

[s-barannikov]

Looks like I'll have to fix the tablegen backend first.