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Merged
merged 1 commit into from
Jul 25, 2025
Merged

[CIR] Add folders for bit manipulation operations #150235

merged 1 commit into from
Jul 25, 2025
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Lancern
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@Lancern Lancern commented Jul 23, 2025

This patch adds folders for the bit manipulation operations, namely: clrsb, clz, ctz, parity, popcount, bitreverse, byte_swap, and rotate.

@llvmbot llvmbot added clang Clang issues not falling into any other category ClangIR Anything related to the ClangIR project labels Jul 23, 2025
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llvmbot commented Jul 23, 2025

@llvm/pr-subscribers-clangir

Author: Sirui Mu (Lancern)

Changes

This patch adds folders for the bit manipulation operations, namely: clrsb, clz, ctz, parity, popcount, bitreverse, byte_swap, and rotate.

Full diff: https://github.com/llvm/llvm-project/pull/150235.diff

4 Files Affected:

  • (modified) clang/include/clang/CIR/Dialect/IR/CIROps.td (+4)
  • (modified) clang/lib/CIR/Dialect/IR/CIRDialect.cpp (+112)
  • (modified) clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp (+2-1)
  • (added) clang/test/CIR/Transforms/bit.cir (+129)
diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index 694e3691c9361..8d5d34782c9a8 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -2773,6 +2773,8 @@ class CIR_BitOpBase<string mnemonic, TypeConstraint operandTy>
   let assemblyFormat = [{
     $input `:` type($result) attr-dict
   }];
+
+  let hasFolder = 1;
 }
 
 class CIR_BitZeroCountOpBase<string mnemonic, TypeConstraint operandTy>
@@ -2980,6 +2982,8 @@ def CIR_RotateOp : CIR_Op<"rotate", [Pure, SameOperandsAndResultType]> {
     bool isRotateLeft() { return getRotateLeft(); }
     bool isRotateRight() { return !getRotateLeft(); }
   }];
+
+  let hasFolder = 1;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
index f0416b6aba6e4..8e13900043108 100644
--- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
@@ -17,6 +17,7 @@
 
 #include "mlir/Interfaces/ControlFlowInterfaces.h"
 #include "mlir/Interfaces/FunctionImplementation.h"
+#include "mlir/Support/LLVM.h"
 
 #include "clang/CIR/Dialect/IR/CIROpsDialect.cpp.inc"
 #include "clang/CIR/Dialect/IR/CIROpsEnums.cpp.inc"
@@ -2132,6 +2133,117 @@ LogicalResult cir::ComplexImagPtrOp::verify() {
   return success();
 }
 
+//===----------------------------------------------------------------------===//
+// Bit manipulation operations
+//===----------------------------------------------------------------------===//
+
+template <typename F>
+static OpFoldResult foldUnaryBitOp(mlir::Attribute inputAttr, F func,
+                                   bool poisonZero = false) {
+  auto input = mlir::dyn_cast_if_present<IntAttr>(inputAttr);
+  if (!input)
+    return nullptr;
+
+  llvm::APInt inputValue = input.getValue();
+  if (poisonZero && inputValue.isZero()) {
+    // TODO(cir): maybe we should return a poison value here?
+    return nullptr;
+  }
+
+  auto resultValue = func(inputValue);
+  if constexpr (std::is_integral_v<decltype(resultValue)>)
+    return IntAttr::get(input.getType(), resultValue);
+  else
+    return IntAttr::get(input.getContext(), input.getType(), resultValue);
+}
+
+OpFoldResult BitClrsbOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.getBitWidth() - inputValue.getSignificantBits();
+  });
+}
+
+OpFoldResult BitClzOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(
+      adaptor.getInput(),
+      [](const llvm::APInt &inputValue) {
+        return inputValue.countLeadingZeros();
+      },
+      getPoisonZero());
+}
+
+OpFoldResult BitCtzOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(
+      adaptor.getInput(),
+      [](const llvm::APInt &inputValue) {
+        return inputValue.countTrailingZeros();
+      },
+      getPoisonZero());
+}
+
+OpFoldResult BitParityOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.popcount() % 2;
+  });
+}
+
+OpFoldResult BitPopcountOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.popcount();
+  });
+}
+
+OpFoldResult BitReverseOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.reverseBits();
+  });
+}
+
+OpFoldResult ByteSwapOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.byteSwap();
+  });
+}
+
+OpFoldResult RotateOp::fold(FoldAdaptor adaptor) {
+  auto input = mlir::dyn_cast_if_present<IntAttr>(adaptor.getInput());
+  auto amount = mlir::dyn_cast_if_present<IntAttr>(adaptor.getAmount());
+  if (!input && !amount)
+    return nullptr;
+
+  llvm::APInt inputValue;
+  if (input) {
+    inputValue = input.getValue();
+    if (inputValue.isZero() || inputValue.isAllOnes()) {
+      // An input value of all 0s or all 1s will not change after rotation
+      return input;
+    }
+  }
+
+  uint64_t amountValue;
+  if (amount) {
+    amountValue = amount.getValue().urem(getInput().getType().getWidth());
+    if (amountValue == 0) {
+      // A shift amount of 0 will not change the input value
+      return getInput();
+    }
+  }
+
+  if (!input || !amount)
+    return nullptr;
+
+  assert(inputValue.getBitWidth() == getInput().getType().getWidth() &&
+         "input value must have the same bit width as the input type");
+
+  llvm::APInt resultValue;
+  if (isRotateLeft())
+    resultValue = inputValue.rotl(amountValue);
+  else
+    resultValue = inputValue.rotr(amountValue);
+
+  return IntAttr::get(input.getContext(), input.getType(), resultValue);
+}
+
 //===----------------------------------------------------------------------===//
 // TableGen'd op method definitions
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp b/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp
index e505db50d3609..2143f167ba2c8 100644
--- a/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp
+++ b/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp
@@ -143,7 +143,8 @@ void CIRCanonicalizePass::runOnOperation() {
     if (isa<BrOp, BrCondOp, CastOp, ScopeOp, SwitchOp, SelectOp, UnaryOp,
             ComplexCreateOp, ComplexImagOp, ComplexRealOp, VecCmpOp,
             VecCreateOp, VecExtractOp, VecShuffleOp, VecShuffleDynamicOp,
-            VecTernaryOp>(op))
+            VecTernaryOp, BitClrsbOp, BitClzOp, BitCtzOp, BitParityOp,
+            BitPopcountOp, BitReverseOp, ByteSwapOp, RotateOp>(op))
       ops.push_back(op);
   });
 
diff --git a/clang/test/CIR/Transforms/bit.cir b/clang/test/CIR/Transforms/bit.cir
new file mode 100644
index 0000000000000..df804fbef8981
--- /dev/null
+++ b/clang/test/CIR/Transforms/bit.cir
@@ -0,0 +1,129 @@
+// RUN: cir-opt -cir-canonicalize -cir-simplify -o %t.cir %s
+// RUN: FileCheck --input-file=%t.cir %s
+
+!s32i = !cir.int<s, 32>
+!u32i = !cir.int<u, 32>
+
+module {
+  cir.func @fold_clrsb() -> !s32i {
+    %0 = cir.const #cir.int<114514> : !s32i
+    %1 = cir.clrsb %0 : !s32i
+    cir.return %1 : !s32i
+  }
+  // CHECK-LABEL: @fold_clrsb
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<14> : !s32i
+  // CHECK-NEXT:    cir.return %[[R]] : !s32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_clz() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.clz %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_clz
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<15> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_ctz() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.ctz %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_ctz
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_parity() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.parity %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_parity
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_popcount() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.popcount %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_popcount
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<11> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_bitreverse() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.bitreverse %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_bitreverse
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1258127360> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_byte_swap() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.byte_swap %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_byte_swap
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1388249344> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_input_all_zeros(%arg0 : !u32i) -> !u32i {
+    %0 = cir.const #cir.int<0> : !u32i
+    %1 = cir.rotate left %0, %arg0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_input_all_zeros
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<0> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_input_all_ones(%arg0 : !u32i) -> !u32i {
+    %0 = cir.const #cir.int<4294967295> : !u32i
+    %1 = cir.rotate left %0, %arg0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_input_all_ones
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<4294967295> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_zero_amount(%arg0 : !u32i) -> !u32i {
+    %0 = cir.const #cir.int<32> : !u32i
+    %1 = cir.rotate left %arg0, %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_zero_amount
+  // CHECK-SAME:  (%[[R:.+]]: !u32i)
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_left() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.const #cir.int<7> : !u32i
+    %2 = cir.rotate left %0, %1 : !u32i
+    cir.return %2 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_left
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<14657792> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_right() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.const #cir.int<7> : !u32i
+    %2 = cir.rotate right %0, %1 : !u32i
+    cir.return %2 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_right
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<2751464318> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+}

@llvmbot
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llvmbot commented Jul 23, 2025

@llvm/pr-subscribers-clang

Author: Sirui Mu (Lancern)

Changes

This patch adds folders for the bit manipulation operations, namely: clrsb, clz, ctz, parity, popcount, bitreverse, byte_swap, and rotate.

Full diff: https://github.com/llvm/llvm-project/pull/150235.diff

4 Files Affected:

  • (modified) clang/include/clang/CIR/Dialect/IR/CIROps.td (+4)
  • (modified) clang/lib/CIR/Dialect/IR/CIRDialect.cpp (+112)
  • (modified) clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp (+2-1)
  • (added) clang/test/CIR/Transforms/bit.cir (+129)
diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
index 694e3691c9361..8d5d34782c9a8 100644
--- a/clang/include/clang/CIR/Dialect/IR/CIROps.td
+++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -2773,6 +2773,8 @@ class CIR_BitOpBase<string mnemonic, TypeConstraint operandTy>
   let assemblyFormat = [{
     $input `:` type($result) attr-dict
   }];
+
+  let hasFolder = 1;
 }
 
 class CIR_BitZeroCountOpBase<string mnemonic, TypeConstraint operandTy>
@@ -2980,6 +2982,8 @@ def CIR_RotateOp : CIR_Op<"rotate", [Pure, SameOperandsAndResultType]> {
     bool isRotateLeft() { return getRotateLeft(); }
     bool isRotateRight() { return !getRotateLeft(); }
   }];
+
+  let hasFolder = 1;
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
index f0416b6aba6e4..8e13900043108 100644
--- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
+++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp
@@ -17,6 +17,7 @@
 
 #include "mlir/Interfaces/ControlFlowInterfaces.h"
 #include "mlir/Interfaces/FunctionImplementation.h"
+#include "mlir/Support/LLVM.h"
 
 #include "clang/CIR/Dialect/IR/CIROpsDialect.cpp.inc"
 #include "clang/CIR/Dialect/IR/CIROpsEnums.cpp.inc"
@@ -2132,6 +2133,117 @@ LogicalResult cir::ComplexImagPtrOp::verify() {
   return success();
 }
 
+//===----------------------------------------------------------------------===//
+// Bit manipulation operations
+//===----------------------------------------------------------------------===//
+
+template <typename F>
+static OpFoldResult foldUnaryBitOp(mlir::Attribute inputAttr, F func,
+                                   bool poisonZero = false) {
+  auto input = mlir::dyn_cast_if_present<IntAttr>(inputAttr);
+  if (!input)
+    return nullptr;
+
+  llvm::APInt inputValue = input.getValue();
+  if (poisonZero && inputValue.isZero()) {
+    // TODO(cir): maybe we should return a poison value here?
+    return nullptr;
+  }
+
+  auto resultValue = func(inputValue);
+  if constexpr (std::is_integral_v<decltype(resultValue)>)
+    return IntAttr::get(input.getType(), resultValue);
+  else
+    return IntAttr::get(input.getContext(), input.getType(), resultValue);
+}
+
+OpFoldResult BitClrsbOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.getBitWidth() - inputValue.getSignificantBits();
+  });
+}
+
+OpFoldResult BitClzOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(
+      adaptor.getInput(),
+      [](const llvm::APInt &inputValue) {
+        return inputValue.countLeadingZeros();
+      },
+      getPoisonZero());
+}
+
+OpFoldResult BitCtzOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(
+      adaptor.getInput(),
+      [](const llvm::APInt &inputValue) {
+        return inputValue.countTrailingZeros();
+      },
+      getPoisonZero());
+}
+
+OpFoldResult BitParityOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.popcount() % 2;
+  });
+}
+
+OpFoldResult BitPopcountOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.popcount();
+  });
+}
+
+OpFoldResult BitReverseOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.reverseBits();
+  });
+}
+
+OpFoldResult ByteSwapOp::fold(FoldAdaptor adaptor) {
+  return foldUnaryBitOp(adaptor.getInput(), [](const llvm::APInt &inputValue) {
+    return inputValue.byteSwap();
+  });
+}
+
+OpFoldResult RotateOp::fold(FoldAdaptor adaptor) {
+  auto input = mlir::dyn_cast_if_present<IntAttr>(adaptor.getInput());
+  auto amount = mlir::dyn_cast_if_present<IntAttr>(adaptor.getAmount());
+  if (!input && !amount)
+    return nullptr;
+
+  llvm::APInt inputValue;
+  if (input) {
+    inputValue = input.getValue();
+    if (inputValue.isZero() || inputValue.isAllOnes()) {
+      // An input value of all 0s or all 1s will not change after rotation
+      return input;
+    }
+  }
+
+  uint64_t amountValue;
+  if (amount) {
+    amountValue = amount.getValue().urem(getInput().getType().getWidth());
+    if (amountValue == 0) {
+      // A shift amount of 0 will not change the input value
+      return getInput();
+    }
+  }
+
+  if (!input || !amount)
+    return nullptr;
+
+  assert(inputValue.getBitWidth() == getInput().getType().getWidth() &&
+         "input value must have the same bit width as the input type");
+
+  llvm::APInt resultValue;
+  if (isRotateLeft())
+    resultValue = inputValue.rotl(amountValue);
+  else
+    resultValue = inputValue.rotr(amountValue);
+
+  return IntAttr::get(input.getContext(), input.getType(), resultValue);
+}
+
 //===----------------------------------------------------------------------===//
 // TableGen'd op method definitions
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp b/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp
index e505db50d3609..2143f167ba2c8 100644
--- a/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp
+++ b/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp
@@ -143,7 +143,8 @@ void CIRCanonicalizePass::runOnOperation() {
     if (isa<BrOp, BrCondOp, CastOp, ScopeOp, SwitchOp, SelectOp, UnaryOp,
             ComplexCreateOp, ComplexImagOp, ComplexRealOp, VecCmpOp,
             VecCreateOp, VecExtractOp, VecShuffleOp, VecShuffleDynamicOp,
-            VecTernaryOp>(op))
+            VecTernaryOp, BitClrsbOp, BitClzOp, BitCtzOp, BitParityOp,
+            BitPopcountOp, BitReverseOp, ByteSwapOp, RotateOp>(op))
       ops.push_back(op);
   });
 
diff --git a/clang/test/CIR/Transforms/bit.cir b/clang/test/CIR/Transforms/bit.cir
new file mode 100644
index 0000000000000..df804fbef8981
--- /dev/null
+++ b/clang/test/CIR/Transforms/bit.cir
@@ -0,0 +1,129 @@
+// RUN: cir-opt -cir-canonicalize -cir-simplify -o %t.cir %s
+// RUN: FileCheck --input-file=%t.cir %s
+
+!s32i = !cir.int<s, 32>
+!u32i = !cir.int<u, 32>
+
+module {
+  cir.func @fold_clrsb() -> !s32i {
+    %0 = cir.const #cir.int<114514> : !s32i
+    %1 = cir.clrsb %0 : !s32i
+    cir.return %1 : !s32i
+  }
+  // CHECK-LABEL: @fold_clrsb
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<14> : !s32i
+  // CHECK-NEXT:    cir.return %[[R]] : !s32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_clz() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.clz %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_clz
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<15> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_ctz() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.ctz %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_ctz
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_parity() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.parity %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_parity
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_popcount() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.popcount %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_popcount
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<11> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_bitreverse() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.bitreverse %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_bitreverse
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1258127360> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_byte_swap() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.byte_swap %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_byte_swap
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<1388249344> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_input_all_zeros(%arg0 : !u32i) -> !u32i {
+    %0 = cir.const #cir.int<0> : !u32i
+    %1 = cir.rotate left %0, %arg0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_input_all_zeros
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<0> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_input_all_ones(%arg0 : !u32i) -> !u32i {
+    %0 = cir.const #cir.int<4294967295> : !u32i
+    %1 = cir.rotate left %0, %arg0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_input_all_ones
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<4294967295> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_zero_amount(%arg0 : !u32i) -> !u32i {
+    %0 = cir.const #cir.int<32> : !u32i
+    %1 = cir.rotate left %arg0, %0 : !u32i
+    cir.return %1 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_zero_amount
+  // CHECK-SAME:  (%[[R:.+]]: !u32i)
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_left() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.const #cir.int<7> : !u32i
+    %2 = cir.rotate left %0, %1 : !u32i
+    cir.return %2 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_left
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<14657792> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+
+  cir.func @fold_rotate_right() -> !u32i {
+    %0 = cir.const #cir.int<114514> : !u32i
+    %1 = cir.const #cir.int<7> : !u32i
+    %2 = cir.rotate right %0, %1 : !u32i
+    cir.return %2 : !u32i
+  }
+  // CHECK-LABEL: @fold_rotate_right
+  // CHECK-NEXT:    %[[R:.+]] = cir.const #cir.int<2751464318> : !u32i
+  // CHECK-NEXT:    cir.return %[[R]] : !u32i
+  // CHECK-NEXT:  }
+}

andykaylor
andykaylor reviewed Jul 23, 2025
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clang/test/CIR/Transforms/bit.cir Outdated

module {
cir.func @fold_clrsb() -> !s32i {
%0 = cir.const #cir.int<114514> : !s32i
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Was 114514 chosen for any particular reason? The test would be more readable if you chose a number for which the operations could be easily compute mentally and added a comment showing the hex representation of the number.

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It's randomly chosen w/o a specific reason. Updated with comments.

clang/lib/CIR/Dialect/IR/CIRDialect.cpp Outdated
return nullptr;
}

auto resultValue = func(inputValue);
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Can you use mlir::Value rather than auto? I don't think we want to allow functors that return other types.

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I make it an llvm::APInt.

@Lancern Lancern force-pushed the cir/bit-op-folder branch from 7b5e3cd to d216fcd Compare July 24, 2025 14:53
andykaylor
andykaylor approved these changes Jul 24, 2025
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lgtm -- thanks for the test updates!

@Lancern Lancern force-pushed the cir/bit-op-folder branch from d216fcd to 169c89a Compare July 25, 2025 13:02
@Lancern Lancern force-pushed the cir/bit-op-folder branch 2 times, most recently from d431acf to b22e90b Compare July 25, 2025 14:20
@Lancern Lancern merged commit 2b3ca68 into llvm:main Jul 25, 2025
13 of 15 checks passed
@Lancern Lancern deleted the cir/bit-op-folder branch July 25, 2025 16:07
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@Lancern @llvmbot @andykaylor