Reland [arm64][turbofan]: Handle any immediate shift.

src/compiler/arm64/instruction-selector-arm64.cc

Index: src/compiler/arm64/instruction-selector-arm64.cc
diff --git a/src/compiler/arm64/instruction-selector-arm64.cc b/src/compiler/arm64/instruction-selector-arm64.cc
index abe69f46186370fe1eb792d7c7347af30b7b5ce0..1c2f486a5256cfec6f1fe45ddacdb56e2bc30e97 100644
--- a/src/compiler/arm64/instruction-selector-arm64.cc
+++ b/src/compiler/arm64/instruction-selector-arm64.cc
@@ -37,15 +37,31 @@ class Arm64OperandGenerator final : public OperandGenerator {
     return UseRegister(node);
   }
 
+  // Use the provided node if it has the required value, or create a
+  // TempImmediate otherwise.
+  InstructionOperand UseImmediateOrTemp(Node* node, int32_t value) {
+    if (GetIntegerConstantValue(node) == value) {
+      return UseImmediate(node);
+    }
+    return TempImmediate(value);
+  }
+
+  bool IsIntegerConstant(Node* node) {
+    return (node->opcode() == IrOpcode::kInt32Constant) ||
+           (node->opcode() == IrOpcode::kInt64Constant);
+  }
+
+  int64_t GetIntegerConstantValue(Node* node) {
+    if (node->opcode() == IrOpcode::kInt32Constant) {
+      return OpParameter<int32_t>(node);
+    }
+    DCHECK(node->opcode() == IrOpcode::kInt64Constant);
+    return OpParameter<int64_t>(node);
+  }
+
   bool CanBeImmediate(Node* node, ImmediateMode mode) {
-    int64_t value;
-    if (node->opcode() == IrOpcode::kInt32Constant)
-      value = OpParameter<int32_t>(node);
-    else if (node->opcode() == IrOpcode::kInt64Constant)
-      value = OpParameter<int64_t>(node);
-    else
-      return false;
-    return CanBeImmediate(value, mode);
+    return IsIntegerConstant(node) &&
+           CanBeImmediate(GetIntegerConstantValue(node), mode);
   }
 
   bool CanBeImmediate(int64_t value, ImmediateMode mode) {
@@ -61,10 +77,6 @@ class Arm64OperandGenerator final : public OperandGenerator {
                                        &ignored, &ignored, &ignored);
       case kArithmeticImm:
         return Assembler::IsImmAddSub(value);
-      case kShift32Imm:
-        return 0 <= value && value < 32;
-      case kShift64Imm:
-        return 0 <= value && value < 64;
       case kLoadStoreImm8:
         return IsLoadStoreImmediate(value, LSByte);
       case kLoadStoreImm16:
@@ -75,6 +87,12 @@ class Arm64OperandGenerator final : public OperandGenerator {
         return IsLoadStoreImmediate(value, LSDoubleWord);
       case kNoImmediate:
         return false;
+      case kShift32Imm:  // Fall through.
+      case kShift64Imm:
+        // Shift operations only observe the bottom 5 or 6 bits of the value.
+        // All possible shifts can be encoded by discarding bits which have no
+        // effect.
+        return true;
     }
     return false;
   }
@@ -113,47 +131,36 @@ void VisitRRO(InstructionSelector* selector, ArchOpcode opcode, Node* node,
 }
 
 
-template <typename Matcher>
-bool TryMatchShift(InstructionSelector* selector, Node* node,
-                   InstructionCode* opcode, IrOpcode::Value shift_opcode,
-                   ImmediateMode imm_mode, AddressingMode addressing_mode) {
-  if (node->opcode() != shift_opcode) return false;
-  Arm64OperandGenerator g(selector);
-  Matcher m(node);
-  if (g.CanBeImmediate(m.right().node(), imm_mode)) {
-    *opcode |= AddressingModeField::encode(addressing_mode);
-    return true;
-  }
-  return false;
-}
-
-
 bool TryMatchAnyShift(InstructionSelector* selector, Node* node,
                       InstructionCode* opcode, bool try_ror) {
-  return TryMatchShift<Int32BinopMatcher>(selector, node, opcode,
-                                          IrOpcode::kWord32Shl, kShift32Imm,
-                                          kMode_Operand2_R_LSL_I) ||
-         TryMatchShift<Int32BinopMatcher>(selector, node, opcode,
-                                          IrOpcode::kWord32Shr, kShift32Imm,
-                                          kMode_Operand2_R_LSR_I) ||
-         TryMatchShift<Int32BinopMatcher>(selector, node, opcode,
-                                          IrOpcode::kWord32Sar, kShift32Imm,
-                                          kMode_Operand2_R_ASR_I) ||
-         (try_ror && TryMatchShift<Int32BinopMatcher>(
-                         selector, node, opcode, IrOpcode::kWord32Ror,
-                         kShift32Imm, kMode_Operand2_R_ROR_I)) ||
-         TryMatchShift<Int64BinopMatcher>(selector, node, opcode,
-                                          IrOpcode::kWord64Shl, kShift64Imm,
-                                          kMode_Operand2_R_LSL_I) ||
-         TryMatchShift<Int64BinopMatcher>(selector, node, opcode,
-                                          IrOpcode::kWord64Shr, kShift64Imm,
-                                          kMode_Operand2_R_LSR_I) ||
-         TryMatchShift<Int64BinopMatcher>(selector, node, opcode,
-                                          IrOpcode::kWord64Sar, kShift64Imm,
-                                          kMode_Operand2_R_ASR_I) ||
-         (try_ror && TryMatchShift<Int64BinopMatcher>(
-                         selector, node, opcode, IrOpcode::kWord64Ror,
-                         kShift64Imm, kMode_Operand2_R_ROR_I));
+  Arm64OperandGenerator g(selector);
+
+  if (node->InputCount() != 2) return false;
+  if (!g.IsIntegerConstant(node->InputAt(1))) return false;
+
+  switch (node->opcode()) {
+    case IrOpcode::kWord32Shl:
+    case IrOpcode::kWord64Shl:
+      *opcode |= AddressingModeField::encode(kMode_Operand2_R_LSL_I);
+      return true;
+    case IrOpcode::kWord32Shr:
+    case IrOpcode::kWord64Shr:
+      *opcode |= AddressingModeField::encode(kMode_Operand2_R_LSR_I);
+      return true;
+    case IrOpcode::kWord32Sar:
+    case IrOpcode::kWord64Sar:
+      *opcode |= AddressingModeField::encode(kMode_Operand2_R_ASR_I);
+      return true;
+    case IrOpcode::kWord32Ror:
+    case IrOpcode::kWord64Ror:
+      if (try_ror) {
+        *opcode |= AddressingModeField::encode(kMode_Operand2_R_ROR_I);
+        return true;
+      }
+      return false;
+    default:
+      return false;
+  }
 }
 
 
@@ -548,17 +555,20 @@ void InstructionSelector::VisitWord32And(Node* node) {
       // Select Ubfx for And(Shr(x, imm), mask) where the mask is in the least
       // significant bits.
       Int32BinopMatcher mleft(m.left().node());
-      if (mleft.right().IsInRange(0, 31)) {
+      if (mleft.right().HasValue()) {
+        // Any shift value can match; int32 shifts use `value % 32`.
+        uint32_t lsb = mleft.right().Value() & 0x1f;
+
         // Ubfx cannot extract bits past the register size, however since
         // shifting the original value would have introduced some zeros we can
         // still use ubfx with a smaller mask and the remaining bits will be
         // zeros.
-        uint32_t lsb = mleft.right().Value();
         if (lsb + mask_width > 32) mask_width = 32 - lsb;
 
         Emit(kArm64Ubfx32, g.DefineAsRegister(node),
              g.UseRegister(mleft.left().node()),
-             g.UseImmediate(mleft.right().node()), g.TempImmediate(mask_width));
+             g.UseImmediateOrTemp(mleft.right().node(), lsb),
+             g.TempImmediate(mask_width));
         return;
       }
       // Other cases fall through to the normal And operation.
@@ -585,17 +595,19 @@ void InstructionSelector::VisitWord64And(Node* node) {
       // Select Ubfx for And(Shr(x, imm), mask) where the mask is in the least
       // significant bits.
       Int64BinopMatcher mleft(m.left().node());
-      if (mleft.right().IsInRange(0, 63)) {
+      if (mleft.right().HasValue()) {
+        // Any shift value can match; int64 shifts use `value % 64`.
+        uint32_t lsb = static_cast<uint32_t>(mleft.right().Value() & 0x3f);
+
         // Ubfx cannot extract bits past the register size, however since
         // shifting the original value would have introduced some zeros we can
         // still use ubfx with a smaller mask and the remaining bits will be
         // zeros.
-        uint64_t lsb = mleft.right().Value();
         if (lsb + mask_width > 64) mask_width = 64 - lsb;
 
         Emit(kArm64Ubfx, g.DefineAsRegister(node),
              g.UseRegister(mleft.left().node()),
-             g.UseImmediate(mleft.right().node()),
+             g.UseImmediateOrTemp(mleft.right().node(), lsb),
              g.TempImmediate(static_cast<int32_t>(mask_width)));
         return;
       }
@@ -724,20 +736,21 @@ bool TryEmitBitfieldExtract32(InstructionSelector* selector, Node* node) {
 
 void InstructionSelector::VisitWord32Shr(Node* node) {
   Int32BinopMatcher m(node);
-  if (m.left().IsWord32And() && m.right().IsInRange(0, 31)) {
-    uint32_t lsb = m.right().Value();
+  if (m.left().IsWord32And() && m.right().HasValue()) {
+    uint32_t lsb = m.right().Value() & 0x1f;
     Int32BinopMatcher mleft(m.left().node());
     if (mleft.right().HasValue()) {
+      // Select Ubfx for Shr(And(x, mask), imm) where the result of the mask is
+      // shifted into the least-significant bits.
       uint32_t mask = (mleft.right().Value() >> lsb) << lsb;
-      uint32_t mask_width = base::bits::CountPopulation32(mask);
-      uint32_t mask_msb = base::bits::CountLeadingZeros32(mask);
-      // Select Ubfx for Shr(And(x, mask), imm) where the result of the mask is
-      // shifted into the least-significant bits.
+      unsigned mask_width = base::bits::CountPopulation32(mask);
+      unsigned mask_msb = base::bits::CountLeadingZeros32(mask);
       if ((mask_msb + mask_width + lsb) == 32) {
         Arm64OperandGenerator g(this);
         DCHECK_EQ(lsb, base::bits::CountTrailingZeros32(mask));
         Emit(kArm64Ubfx32, g.DefineAsRegister(node),
-             g.UseRegister(mleft.left().node()), g.TempImmediate(lsb),
+             g.UseRegister(mleft.left().node()),
+             g.UseImmediateOrTemp(m.right().node(), lsb),
              g.TempImmediate(mask_width));
         return;
       }
@@ -766,23 +779,23 @@ void InstructionSelector::VisitWord32Shr(Node* node) {
 
 
 void InstructionSelector::VisitWord64Shr(Node* node) {
-  Arm64OperandGenerator g(this);
   Int64BinopMatcher m(node);
-  if (m.left().IsWord64And() && m.right().IsInRange(0, 63)) {
-    uint64_t lsb = m.right().Value();
+  if (m.left().IsWord64And() && m.right().HasValue()) {
+    uint32_t lsb = m.right().Value() & 0x3f;
     Int64BinopMatcher mleft(m.left().node());
     if (mleft.right().HasValue()) {
       // Select Ubfx for Shr(And(x, mask), imm) where the result of the mask is
       // shifted into the least-significant bits.
       uint64_t mask = (mleft.right().Value() >> lsb) << lsb;
-      uint64_t mask_width = base::bits::CountPopulation64(mask);
-      uint64_t mask_msb = base::bits::CountLeadingZeros64(mask);
+      unsigned mask_width = base::bits::CountPopulation64(mask);
+      unsigned mask_msb = base::bits::CountLeadingZeros64(mask);
       if ((mask_msb + mask_width + lsb) == 64) {
+        Arm64OperandGenerator g(this);
         DCHECK_EQ(lsb, base::bits::CountTrailingZeros64(mask));
         Emit(kArm64Ubfx, g.DefineAsRegister(node),
              g.UseRegister(mleft.left().node()),
-             g.TempImmediate(static_cast<int32_t>(lsb)),
-             g.TempImmediate(static_cast<int32_t>(mask_width)));
+             g.UseImmediateOrTemp(m.right().node(), lsb),
+             g.TempImmediate(mask_width));
         return;
       }
     }