[CIR] Add support for atomic test-and-set and atomic clear (llvm#164162)

Lancern · aokblast · commit 47baff8043da · 2025-10-31T00:08:19.000+08:00
This patch adds support for the following atomic builtin functions:
  - `__atomic_test_and_set`
  - `__atomic_clear`
diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td
@@ -4557,4 +4557,66 @@ def CIR_AtomicCmpXchgOp : CIR_Op<"atomic.cmpxchg", [
   }];
 }
 
+def CIR_AtomicTestAndSetOp : CIR_Op<"atomic.test_and_set"> {
+  let summary = "Atomic test and set";
+  let description = [{
+    C/C++ atomic test and set operation. Implements the builtin function
+    `__atomic_test_and_set`.
+
+    The operation takes as its only operand a pointer to an 8-bit signed
+    integer. The operation atomically set the integer to an implementation-
+    defined non-zero "set" value. The result of the operation is a boolean value
+    indicating whether the previous value of the integer was the "set" value.
+
+    Example:
+    ```mlir
+      %res = cir.atomic.test_and_set seq_cst %ptr : !cir.ptr<!s8i> -> !cir.bool
+    ```
+  }];
+
+  let arguments = (ins
+    Arg<CIR_PtrToType<CIR_SInt8>, "", [MemRead, MemWrite]>:$ptr,
+    Arg<CIR_MemOrder, "memory order">:$mem_order,
+    OptionalAttr<I64Attr>:$alignment,
+    UnitAttr:$is_volatile
+  );
+
+  let results = (outs CIR_BoolType:$result);
+
+  let assemblyFormat = [{
+    $mem_order $ptr
+    (`volatile` $is_volatile^)?
+    `:` qualified(type($ptr)) `->` qualified(type($result)) attr-dict
+  }];
+}
+
+def CIR_AtomicClearOp : CIR_Op<"atomic.clear"> {
+  let summary = "Atomic clear";
+  let description = [{
+    C/C++ atomic clear operation. Implements the builtin function
+    `__atomic_clear`.
+
+    The operation takes as its only operand a pointer to an 8-bit signed
+    integer. The operation atomically sets the integer to zero.
+
+    Example:
+    ```mlir
+      cir.atomic.clear seq_cst %ptr : !cir.ptr<!s8i>
+    ```
+  }];
+
+  let arguments = (ins
+    Arg<CIR_PtrToType<CIR_SInt8>, "", [MemRead, MemWrite]>:$ptr,
+    Arg<CIR_MemOrder, "memory order">:$mem_order,
+    OptionalAttr<I64Attr>:$alignment,
+    UnitAttr:$is_volatile
+  );
+
+  let assemblyFormat = [{
+    $mem_order $ptr
+    (`volatile` $is_volatile^)?
+    `:` qualified(type($ptr)) attr-dict
+  }];
+}
+
 #endif // CLANG_CIR_DIALECT_IR_CIROPS_TD
diff --git a/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp b/clang/lib/CIR/CodeGen/CIRGenAtomic.cpp
@@ -407,6 +407,23 @@ static void emitAtomicOp(CIRGenFunction &cgf, AtomicExpr *expr, Address dest,
     opName = cir::AtomicXchgOp::getOperationName();
     break;
 
+  case AtomicExpr::AO__atomic_test_and_set: {
+    auto op = cir::AtomicTestAndSetOp::create(
+        builder, loc, ptr.getPointer(), order,
+        builder.getI64IntegerAttr(ptr.getAlignment().getQuantity()),
+        expr->isVolatile());
+    builder.createStore(loc, op, dest);
+    return;
+  }
+
+  case AtomicExpr::AO__atomic_clear: {
+    cir::AtomicClearOp::create(
+        builder, loc, ptr.getPointer(), order,
+        builder.getI64IntegerAttr(ptr.getAlignment().getQuantity()),
+        expr->isVolatile());
+    return;
+  }
+
   case AtomicExpr::AO__opencl_atomic_init:
 
   case AtomicExpr::AO__hip_atomic_compare_exchange_strong:
@@ -502,10 +519,6 @@ static void emitAtomicOp(CIRGenFunction &cgf, AtomicExpr *expr, Address dest,
   case AtomicExpr::AO__c11_atomic_fetch_nand:
   case AtomicExpr::AO__atomic_fetch_nand:
   case AtomicExpr::AO__scoped_atomic_fetch_nand:
-
-  case AtomicExpr::AO__atomic_test_and_set:
-
-  case AtomicExpr::AO__atomic_clear:
     cgf.cgm.errorNYI(expr->getSourceRange(), "emitAtomicOp: expr op NYI");
     return;
   }
@@ -581,6 +594,8 @@ RValue CIRGenFunction::emitAtomicExpr(AtomicExpr *e) {
 
   case AtomicExpr::AO__atomic_load_n:
   case AtomicExpr::AO__c11_atomic_load:
+  case AtomicExpr::AO__atomic_test_and_set:
+  case AtomicExpr::AO__atomic_clear:
     break;
 
   case AtomicExpr::AO__atomic_load:
@@ -640,6 +655,9 @@ RValue CIRGenFunction::emitAtomicExpr(AtomicExpr *e) {
       dest = atomics.castToAtomicIntPointer(dest);
   } else if (e->isCmpXChg()) {
     dest = createMemTemp(resultTy, getLoc(e->getSourceRange()), "cmpxchg.bool");
+  } else if (e->getOp() == AtomicExpr::AO__atomic_test_and_set) {
+    dest = createMemTemp(resultTy, getLoc(e->getSourceRange()),
+                         "test_and_set.bool");
   } else if (!resultTy->isVoidType()) {
     dest = atomics.createTempAlloca();
     if (shouldCastToIntPtrTy)
diff --git a/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp b/clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp
@@ -730,6 +730,46 @@ mlir::LogicalResult CIRToLLVMAtomicXchgOpLowering::matchAndRewrite(
   return mlir::success();
 }
 
+mlir::LogicalResult CIRToLLVMAtomicTestAndSetOpLowering::matchAndRewrite(
+    cir::AtomicTestAndSetOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  assert(!cir::MissingFeatures::atomicSyncScopeID());
+
+  mlir::LLVM::AtomicOrdering llvmOrder = getLLVMMemOrder(op.getMemOrder());
+
+  auto one = mlir::LLVM::ConstantOp::create(rewriter, op.getLoc(),
+                                            rewriter.getI8Type(), 1);
+  auto rmw = mlir::LLVM::AtomicRMWOp::create(
+      rewriter, op.getLoc(), mlir::LLVM::AtomicBinOp::xchg, adaptor.getPtr(),
+      one, llvmOrder, /*syncscope=*/llvm::StringRef(),
+      adaptor.getAlignment().value_or(0), op.getIsVolatile());
+
+  auto zero = mlir::LLVM::ConstantOp::create(rewriter, op.getLoc(),
+                                             rewriter.getI8Type(), 0);
+  auto cmp = mlir::LLVM::ICmpOp::create(
+      rewriter, op.getLoc(), mlir::LLVM::ICmpPredicate::ne, rmw, zero);
+
+  rewriter.replaceOp(op, cmp);
+  return mlir::success();
+}
+
+mlir::LogicalResult CIRToLLVMAtomicClearOpLowering::matchAndRewrite(
+    cir::AtomicClearOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  assert(!cir::MissingFeatures::atomicSyncScopeID());
+
+  mlir::LLVM::AtomicOrdering llvmOrder = getLLVMMemOrder(op.getMemOrder());
+  auto zero = mlir::LLVM::ConstantOp::create(rewriter, op.getLoc(),
+                                             rewriter.getI8Type(), 0);
+  auto store = mlir::LLVM::StoreOp::create(
+      rewriter, op.getLoc(), zero, adaptor.getPtr(),
+      adaptor.getAlignment().value_or(0), op.getIsVolatile(),
+      /*isNonTemporal=*/false, /*isInvariantGroup=*/false, llvmOrder);
+
+  rewriter.replaceOp(op, store);
+  return mlir::success();
+}
+
 mlir::LogicalResult CIRToLLVMBitClrsbOpLowering::matchAndRewrite(
     cir::BitClrsbOp op, OpAdaptor adaptor,
     mlir::ConversionPatternRewriter &rewriter) const {
diff --git a/clang/test/CIR/CodeGen/atomic.c b/clang/test/CIR/CodeGen/atomic.c
@@ -514,3 +514,73 @@ void atomic_exchange_n(int *ptr, int value) {
   // OGCG: %{{.+}} = atomicrmw xchg ptr %{{.+}}, i32 %{{.+}} acq_rel, align 4
   // OGCG: %{{.+}} = atomicrmw xchg ptr %{{.+}}, i32 %{{.+}} seq_cst, align 4
 }
+
+void test_and_set(void *p) {
+  // CIR-LABEL: @test_and_set
+  // LLVM-LABEL: @test_and_set
+  // OGCG-LABEL: @test_and_set
+
+  __atomic_test_and_set(p, __ATOMIC_SEQ_CST);
+  // CIR:      %[[VOID_PTR:.+]] = cir.load align(8) %{{.+}} : !cir.ptr<!cir.ptr<!void>>, !cir.ptr<!void>
+  // CIR-NEXT: %[[PTR:.+]] = cir.cast bitcast %[[VOID_PTR]] : !cir.ptr<!void> -> !cir.ptr<!s8i>
+  // CIR-NEXT: %[[RES:.+]] = cir.atomic.test_and_set seq_cst %[[PTR]] : !cir.ptr<!s8i> -> !cir.bool
+  // CIR-NEXT: cir.store align(1) %[[RES]], %{{.+}} : !cir.bool, !cir.ptr<!cir.bool>
+
+  // LLVM:      %[[PTR:.+]] = load ptr, ptr %{{.+}}, align 8
+  // LLVM-NEXT: %[[RES:.+]] = atomicrmw xchg ptr %[[PTR]], i8 1 seq_cst, align 1
+  // LLVM-NEXT: %{{.+}} = icmp ne i8 %[[RES]], 0
+
+  // OGCG:      %[[PTR:.+]] = load ptr, ptr %{{.+}}, align 8
+  // OGCG-NEXT: %[[RES:.+]] = atomicrmw xchg ptr %[[PTR]], i8 1 seq_cst, align 1
+  // OGCG-NEXT: %{{.+}} = icmp ne i8 %[[RES]], 0
+}
+
+void test_and_set_volatile(volatile void *p) {
+  // CIR-LABEL: @test_and_set_volatile
+  // LLVM-LABEL: @test_and_set_volatile
+  // OGCG-LABEL: @test_and_set_volatile
+
+  __atomic_test_and_set(p, __ATOMIC_SEQ_CST);
+  // CIR:      %[[VOID_PTR:.+]] = cir.load align(8) %{{.+}} : !cir.ptr<!cir.ptr<!void>>, !cir.ptr<!void>
+  // CIR-NEXT: %[[PTR:.+]] = cir.cast bitcast %[[VOID_PTR]] : !cir.ptr<!void> -> !cir.ptr<!s8i>
+  // CIR-NEXT: %[[RES:.+]] = cir.atomic.test_and_set seq_cst %[[PTR]] volatile : !cir.ptr<!s8i> -> !cir.bool
+  // CIR-NEXT: cir.store align(1) %[[RES]], %{{.+}} : !cir.bool, !cir.ptr<!cir.bool>
+
+  // LLVM:      %[[PTR:.+]] = load ptr, ptr %{{.+}}, align 8
+  // LLVM-NEXT: %[[RES:.+]] = atomicrmw volatile xchg ptr %[[PTR]], i8 1 seq_cst, align 1
+  // LLVM-NEXT: %{{.+}} = icmp ne i8 %[[RES]], 0
+
+  // OGCG:      %[[PTR:.+]] = load ptr, ptr %{{.+}}, align 8
+  // OGCG-NEXT: %[[RES:.+]] = atomicrmw volatile xchg ptr %[[PTR]], i8 1 seq_cst, align 1
+  // OGCG-NEXT: %{{.+}} = icmp ne i8 %[[RES]], 0
+}
+
+void clear(void *p) {
+  // CIR-LABEL: @clear
+  // LLVM-LABEL: @clear
+  // OGCG-LABEL: @clear
+
+  __atomic_clear(p, __ATOMIC_SEQ_CST);
+  // CIR:      %[[VOID_PTR:.+]] = cir.load align(8) %{{.+}} : !cir.ptr<!cir.ptr<!void>>, !cir.ptr<!void>
+  // CIR-NEXT: %[[PTR:.+]] = cir.cast bitcast %[[VOID_PTR]] : !cir.ptr<!void> -> !cir.ptr<!s8i>
+  // CIR:      cir.atomic.clear seq_cst %[[PTR]] : !cir.ptr<!s8i>
+
+  // LLVM: store atomic i8 0, ptr %{{.+}} seq_cst, align 1
+
+  // OGCG: store atomic i8 0, ptr %{{.+}} seq_cst, align 1
+}
+
+void clear_volatile(volatile void *p) {
+  // CIR-LABEL: @clear_volatile
+  // LLVM-LABEL: @clear_volatile
+  // OGCG-LABEL: @clear_volatile
+
+  __atomic_clear(p, __ATOMIC_SEQ_CST);
+  // CIR:      %[[VOID_PTR:.+]] = cir.load align(8) %{{.+}} : !cir.ptr<!cir.ptr<!void>>, !cir.ptr<!void>
+  // CIR-NEXT: %[[PTR:.+]] = cir.cast bitcast %[[VOID_PTR]] : !cir.ptr<!void> -> !cir.ptr<!s8i>
+  // CIR:      cir.atomic.clear seq_cst %[[PTR]] volatile : !cir.ptr<!s8i>
+
+  // LLVM: store atomic volatile i8 0, ptr %{{.+}} seq_cst, align 1
+
+  // OGCG: store atomic volatile i8 0, ptr %{{.+}} seq_cst, align 1
+}
