[RISCV][GISel] Implement zexti32/zexti16 ComplexPatterns. (#115097)

Author: topperc

llvm/lib/Target/RISCV/GISel/RISCVInstructionSelector.cpp

@@ -87,6 +87,12 @@ class RISCVInstructionSelector : public InstructionSelector {
   ComplexRendererFns selectShiftMask(MachineOperand &Root) const;
   ComplexRendererFns selectAddrRegImm(MachineOperand &Root) const;
 
+  ComplexRendererFns selectZExtBits(MachineOperand &Root, unsigned Bits) const;
+  template <unsigned Bits>
+  ComplexRendererFns selectZExtBits(MachineOperand &Root) const {
+    return selectZExtBits(Root, Bits);
+  }
+
   ComplexRendererFns selectSHXADDOp(MachineOperand &Root, unsigned ShAmt) const;
   template <unsigned ShAmt>
   ComplexRendererFns selectSHXADDOp(MachineOperand &Root) const {
@@ -242,6 +248,24 @@ RISCVInstructionSelector::selectShiftMask(MachineOperand &Root) const {
   return {{[=](MachineInstrBuilder &MIB) { MIB.addReg(ShAmtReg); }}};
 }
 
+InstructionSelector::ComplexRendererFns
+RISCVInstructionSelector::selectZExtBits(MachineOperand &Root,
+                                         unsigned Bits) const {
+  if (!Root.isReg())
+    return std::nullopt;
+  Register RootReg = Root.getReg();
+
+  Register RegX;
+  uint64_t Mask = maskTrailingOnes<uint64_t>(Bits);
+  if (mi_match(RootReg, *MRI, m_GAnd(m_Reg(RegX), m_SpecificICst(Mask)))) {
+    return {{[=](MachineInstrBuilder &MIB) { MIB.addReg(RegX); }}};
+  }
+
+  // TODO: Use computeKnownBits.
+
+  return std::nullopt;
+}
+
 InstructionSelector::ComplexRendererFns
 RISCVInstructionSelector::selectSHXADDOp(MachineOperand &Root,
                                          unsigned ShAmt) const {

llvm/lib/Target/RISCV/RISCVGISel.td

@@ -96,6 +96,11 @@ def gi_sh2add_uw_op : GIComplexOperandMatcher<s32, "selectSHXADD_UWOp<2>">,
 def gi_sh3add_uw_op : GIComplexOperandMatcher<s32, "selectSHXADD_UWOp<3>">,
                       GIComplexPatternEquiv<sh3add_uw_op>;
 
+def gi_zexti32 : GIComplexOperandMatcher<s64, "selectZExtBits<32>">,
+                 GIComplexPatternEquiv<zexti32>;
+def gi_zexti16 : GIComplexOperandMatcher<s32, "selectZExtBits<16>">,
+                 GIComplexPatternEquiv<zexti16>;
+
 // Ptr type used in patterns with GlobalISelEmitter
 def PtrVT : PtrValueTypeByHwMode<XLenVT, 0>;
 

llvm/test/CodeGen/RISCV/GlobalISel/rv32zbkb.ll

@@ -16,9 +16,7 @@ define i32 @pack_i32(i32 %a, i32 %b) nounwind {
 ;
 ; RV32ZBKB-LABEL: pack_i32:
 ; RV32ZBKB:       # %bb.0:
-; RV32ZBKB-NEXT:    zext.h a0, a0
-; RV32ZBKB-NEXT:    slli a1, a1, 16
-; RV32ZBKB-NEXT:    or a0, a1, a0
+; RV32ZBKB-NEXT:    pack a0, a0, a1
 ; RV32ZBKB-NEXT:    ret
   %shl = and i32 %a, 65535
   %shl1 = shl i32 %b, 16

llvm/test/CodeGen/RISCV/GlobalISel/rv64zbkb.ll

@@ -85,10 +85,7 @@ define i64 @pack_i64(i64 %a, i64 %b) nounwind {
 ;
 ; RV64ZBKB-LABEL: pack_i64:
 ; RV64ZBKB:       # %bb.0:
-; RV64ZBKB-NEXT:    slli a0, a0, 32
-; RV64ZBKB-NEXT:    srli a0, a0, 32
-; RV64ZBKB-NEXT:    slli a1, a1, 32
-; RV64ZBKB-NEXT:    or a0, a1, a0
+; RV64ZBKB-NEXT:    pack a0, a0, a1
 ; RV64ZBKB-NEXT:    ret
   %shl = and i64 %a, 4294967295
   %shl1 = shl i64 %b, 32
@@ -109,12 +106,9 @@ define i64 @pack_i64_2(i32 signext %a, i32 signext %b) nounwind {
 ;
 ; RV64ZBKB-LABEL: pack_i64_2:
 ; RV64ZBKB:       # %bb.0:
-; RV64ZBKB-NEXT:    slli a0, a0, 32
-; RV64ZBKB-NEXT:    srli a0, a0, 32
 ; RV64ZBKB-NEXT:    slli a1, a1, 32
 ; RV64ZBKB-NEXT:    srli a1, a1, 32
-; RV64ZBKB-NEXT:    slli a1, a1, 32
-; RV64ZBKB-NEXT:    or a0, a1, a0
+; RV64ZBKB-NEXT:    pack a0, a0, a1
 ; RV64ZBKB-NEXT:    ret
   %zexta = zext i32 %a to i64
   %zextb = zext i32 %b to i64
@@ -343,10 +337,7 @@ define i64 @pack_i64_allWUsers(i32 signext %0, i32 signext %1, i32 signext %2) {
 ; RV64ZBKB-NEXT:    add a0, a1, a0
 ; RV64ZBKB-NEXT:    slli a0, a0, 32
 ; RV64ZBKB-NEXT:    srli a0, a0, 32
-; RV64ZBKB-NEXT:    slli a0, a0, 32
-; RV64ZBKB-NEXT:    slli a2, a2, 32
-; RV64ZBKB-NEXT:    srli a2, a2, 32
-; RV64ZBKB-NEXT:    or a0, a0, a2
+; RV64ZBKB-NEXT:    pack a0, a2, a0
 ; RV64ZBKB-NEXT:    ret
   %4 = add i32 %1, %0
   %5 = zext i32 %4 to i64