[CIR] Implement __builtin_return_address and __builtin_frame_address (#153698)

This adds ReturnAddrOp and FrameAddrOp that represent
__builtin_return_address and __builtin_frame_address and the respective
lowering to LLVM parts.

---------

Co-authored-by: Andy Kaylor <[email protected]>

Author: mmha

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -2243,6 +2243,68 @@ def CIR_CallOp : CIR_CallOpBase<"call", [NoRegionArguments]> {
   ];
 }
 
+//===----------------------------------------------------------------------===//
+// ReturnAddrOp and FrameAddrOp
+//===----------------------------------------------------------------------===//
+
+class CIR_FuncAddrBuiltinOp<string mnemonic> : CIR_Op<mnemonic, []> {
+  let arguments = (ins CIR_UInt32:$level);
+  let results = (outs CIR_VoidPtrType:$result);
+  let assemblyFormat = [{
+    `(` $level `)` attr-dict
+  }];
+}
+
+def CIR_ReturnAddrOp : CIR_FuncAddrBuiltinOp<"return_address"> {
+  let summary =
+      "The return address of the current function, or of one of its callers";
+
+  let description = [{
+    Represents a call to builtin function ` __builtin_return_address` in CIR.
+    This builtin function returns the return address of the current function,
+    or of one of its callers.
+
+    The `level` argument is number of frames to scan up the call stack.
+    For instance, value of 0 yields the return address of the current function,
+    value of 1 yields the return address of the caller of the current function,
+    and so forth.
+
+    Examples:
+
+    ```mlir
+    %p = return_address(%level) -> !cir.ptr<!void>
+    ```
+  }];
+}
+
+def CIR_FrameAddrOp : CIR_FuncAddrBuiltinOp<"frame_address"> {
+  let summary =
+      "The frame address of the current function, or of one of its callers";
+
+  let description = [{
+    Represents a call to builtin function ` __builtin_frame_address` in CIR.
+    This builtin function returns the frame address of the current function,
+    or of one of its callers. The frame is the area on the stack that holds
+    local variables and saved registers. The frame address is normally the
+    address of the first word pushed on to the stack by the function.
+    However, the exact definition depends upon the processor and the calling
+    convention. If the processor has a dedicated frame pointer register, and
+    the function has a frame, then __builtin_frame_address returns the value of
+    the frame pointer register.
+
+    The `level` argument is number of frames to scan up the call stack.
+    For instance, value of 0 yields the frame address of the current function,
+    value of 1 yields the frame address of the caller of the current function,
+    and so forth.
+
+    Examples:
+
+    ```mlir
+    %p = frame_address(%level) -> !cir.ptr<!void>
+    ```
+  }];
+}
+
 //===----------------------------------------------------------------------===//
 // StackSaveOp & StackRestoreOp
 //===----------------------------------------------------------------------===//

clang/lib/CIR/CodeGen/CIRGenBuilder.h

@@ -267,6 +267,9 @@ class CIRGenBuilderTy : public cir::CIRBaseBuilderTy {
   cir::ConstantOp getSInt32(int32_t c, mlir::Location loc) {
     return getConstantInt(loc, getSInt32Ty(), c);
   }
+  cir::ConstantOp getUInt32(uint32_t c, mlir::Location loc) {
+    return getConstantInt(loc, getUInt32Ty(), c);
+  }
 
   // Creates constant nullptr for pointer type ty.
   cir::ConstantOp getNullPtr(mlir::Type ty, mlir::Location loc) {

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -312,6 +312,20 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
   case Builtin::BI__builtin_rotateright64:
     return emitRotate(e, /*isRotateLeft=*/false);
 
+  case Builtin::BI__builtin_return_address:
+  case Builtin::BI__builtin_frame_address: {
+    mlir::Location loc = getLoc(e->getExprLoc());
+    llvm::APSInt level = e->getArg(0)->EvaluateKnownConstInt(getContext());
+    if (builtinID == Builtin::BI__builtin_return_address) {
+      return RValue::get(cir::ReturnAddrOp::create(
+          builder, loc,
+          builder.getConstAPInt(loc, builder.getUInt32Ty(), level)));
+    }
+    return RValue::get(cir::FrameAddrOp::create(
+        builder, loc,
+        builder.getConstAPInt(loc, builder.getUInt32Ty(), level)));
+  }
+
   case Builtin::BI__builtin_trap:
     emitTrap(loc, /*createNewBlock=*/true);
     return RValue::get(nullptr);

clang/lib/CIR/CodeGen/CIRGenConstantEmitter.h

@@ -80,7 +80,7 @@ class ConstantEmitter {
   //     initializer or to propagate to another context; for example,
   //     side effects, or emitting an initialization that requires a
   //     reference to its current location.
-  mlir::Attribute emitForMemory(mlir::Attribute c, QualType t);
+  mlir::Attribute emitForMemory(mlir::Attribute c, QualType destType);
 
   /// Try to emit the initializer of the given declaration as an abstract
   /// constant.
@@ -90,8 +90,9 @@ class ConstantEmitter {
   /// asserting that it succeeded.  This is only safe to do when the
   /// expression is known to be a constant expression with either a fairly
   /// simple type or a known simple form.
+  mlir::Attribute emitAbstract(const Expr *e, QualType destType);
   mlir::Attribute emitAbstract(SourceLocation loc, const APValue &value,
-                               QualType t);
+                               QualType destType);
 
   mlir::Attribute tryEmitConstantExpr(const ConstantExpr *ce);
 
@@ -101,6 +102,7 @@ class ConstantEmitter {
 
   mlir::Attribute tryEmitPrivateForVarInit(const VarDecl &d);
 
+  mlir::TypedAttr tryEmitPrivate(const Expr *e, QualType destType);
   mlir::Attribute tryEmitPrivate(const APValue &value, QualType destType);
   mlir::Attribute tryEmitPrivateForMemory(const APValue &value, QualType t);
 

clang/lib/CIR/CodeGen/CIRGenExprConstant.cpp

@@ -710,6 +710,16 @@ mlir::Attribute ConstantEmitter::tryEmitPrivateForMemory(const APValue &value,
   return (c ? emitForMemory(c, destType) : nullptr);
 }
 
+mlir::Attribute ConstantEmitter::emitAbstract(const Expr *e,
+                                              QualType destType) {
+  AbstractStateRAII state{*this, true};
+  mlir::Attribute c = mlir::cast<mlir::Attribute>(tryEmitPrivate(e, destType));
+  if (!c)
+    cgm.errorNYI(e->getSourceRange(),
+                 "emitAbstract failed, emit null constaant");
+  return c;
+}
+
 mlir::Attribute ConstantEmitter::emitAbstract(SourceLocation loc,
                                               const APValue &value,
                                               QualType destType) {
@@ -731,6 +741,32 @@ mlir::Attribute ConstantEmitter::emitForMemory(mlir::Attribute c,
   return c;
 }
 
+mlir::TypedAttr ConstantEmitter::tryEmitPrivate(const Expr *e,
+                                                QualType destType) {
+  assert(!destType->isVoidType() && "can't emit a void constant");
+
+  if (mlir::Attribute c =
+          ConstExprEmitter(*this).Visit(const_cast<Expr *>(e), destType))
+    return llvm::dyn_cast<mlir::TypedAttr>(c);
+
+  Expr::EvalResult result;
+
+  bool success = false;
+
+  if (destType->isReferenceType())
+    success = e->EvaluateAsLValue(result, cgm.getASTContext());
+  else
+    success =
+        e->EvaluateAsRValue(result, cgm.getASTContext(), inConstantContext);
+
+  if (success && !result.hasSideEffects()) {
+    mlir::Attribute c = tryEmitPrivate(result.Val, destType);
+    return llvm::dyn_cast<mlir::TypedAttr>(c);
+  }
+
+  return nullptr;
+}
+
 mlir::Attribute ConstantEmitter::tryEmitPrivate(const APValue &value,
                                                 QualType destType) {
   auto &builder = cgm.getBuilder();

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -267,6 +267,26 @@ void convertSideEffectForCall(mlir::Operation *callOp, bool isNothrow,
   }
 }
 
+static mlir::LLVM::CallIntrinsicOp
+createCallLLVMIntrinsicOp(mlir::ConversionPatternRewriter &rewriter,
+                          mlir::Location loc, const llvm::Twine &intrinsicName,
+                          mlir::Type resultTy, mlir::ValueRange operands) {
+  auto intrinsicNameAttr =
+      mlir::StringAttr::get(rewriter.getContext(), intrinsicName);
+  return mlir::LLVM::CallIntrinsicOp::create(rewriter, loc, resultTy,
+                                             intrinsicNameAttr, operands);
+}
+
+static mlir::LLVM::CallIntrinsicOp replaceOpWithCallLLVMIntrinsicOp(
+    mlir::ConversionPatternRewriter &rewriter, mlir::Operation *op,
+    const llvm::Twine &intrinsicName, mlir::Type resultTy,
+    mlir::ValueRange operands) {
+  mlir::LLVM::CallIntrinsicOp callIntrinOp = createCallLLVMIntrinsicOp(
+      rewriter, op->getLoc(), intrinsicName, resultTy, operands);
+  rewriter.replaceOp(op, callIntrinOp.getOperation());
+  return callIntrinOp;
+}
+
 /// IntAttr visitor.
 mlir::Value CIRAttrToValue::visitCirAttr(cir::IntAttr intAttr) {
   mlir::Location loc = parentOp->getLoc();
@@ -1112,6 +1132,24 @@ mlir::LogicalResult CIRToLLVMCallOpLowering::matchAndRewrite(
                              getTypeConverter(), op.getCalleeAttr());
 }
 
+mlir::LogicalResult CIRToLLVMReturnAddrOpLowering::matchAndRewrite(
+    cir::ReturnAddrOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  auto llvmPtrTy = mlir::LLVM::LLVMPointerType::get(rewriter.getContext());
+  replaceOpWithCallLLVMIntrinsicOp(rewriter, op, "llvm.returnaddress",
+                                   llvmPtrTy, adaptor.getOperands());
+  return mlir::success();
+}
+
+mlir::LogicalResult CIRToLLVMFrameAddrOpLowering::matchAndRewrite(
+    cir::FrameAddrOp op, OpAdaptor adaptor,
+    mlir::ConversionPatternRewriter &rewriter) const {
+  auto llvmPtrTy = mlir::LLVM::LLVMPointerType::get(rewriter.getContext());
+  replaceOpWithCallLLVMIntrinsicOp(rewriter, op, "llvm.frameaddress", llvmPtrTy,
+                                   adaptor.getOperands());
+  return mlir::success();
+}
+
 mlir::LogicalResult CIRToLLVMLoadOpLowering::matchAndRewrite(
     cir::LoadOp op, OpAdaptor adaptor,
     mlir::ConversionPatternRewriter &rewriter) const {
@@ -2322,10 +2360,12 @@ void ConvertCIRToLLVMPass::runOnOperation() {
                CIRToLLVMConstantOpLowering,
                CIRToLLVMExpectOpLowering,
                CIRToLLVMFAbsOpLowering,
+               CIRToLLVMFrameAddrOpLowering,
                CIRToLLVMFuncOpLowering,
                CIRToLLVMGetBitfieldOpLowering,
                CIRToLLVMGetGlobalOpLowering,
                CIRToLLVMGetMemberOpLowering,
+               CIRToLLVMReturnAddrOpLowering,
                CIRToLLVMRotateOpLowering,
                CIRToLLVMSelectOpLowering,
                CIRToLLVMSetBitfieldOpLowering,

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.h

@@ -209,6 +209,26 @@ class CIRToLLVMCallOpLowering : public mlir::OpConversionPattern<cir::CallOp> {
                   mlir::ConversionPatternRewriter &rewriter) const override;
 };
 
+class CIRToLLVMReturnAddrOpLowering
+    : public mlir::OpConversionPattern<cir::ReturnAddrOp> {
+public:
+  using mlir::OpConversionPattern<cir::ReturnAddrOp>::OpConversionPattern;
+
+  mlir::LogicalResult
+  matchAndRewrite(cir::ReturnAddrOp op, OpAdaptor,
+                  mlir::ConversionPatternRewriter &) const override;
+};
+
+class CIRToLLVMFrameAddrOpLowering
+    : public mlir::OpConversionPattern<cir::FrameAddrOp> {
+public:
+  using mlir::OpConversionPattern<cir::FrameAddrOp>::OpConversionPattern;
+
+  mlir::LogicalResult
+  matchAndRewrite(cir::FrameAddrOp op, OpAdaptor,
+                  mlir::ConversionPatternRewriter &) const override;
+};
+
 class CIRToLLVMAllocaOpLowering
     : public mlir::OpConversionPattern<cir::AllocaOp> {
   mlir::DataLayout const &dataLayout;

clang/test/CIR/CodeGen/builtins.cpp

@@ -12,3 +12,31 @@ double fabs(double x) {
 // CIR: {{.*}} = cir.fabs {{.*}} : !cir.double
 // LLVM: {{.*}} = call double @llvm.fabs.f64(double {{.*}})
 // OGCG: {{.*}} = call double @llvm.fabs.f64(double {{.*}})
+
+extern "C" void *test_return_address(void) {
+  return __builtin_return_address(1);
+
+  // CIR-LABEL: test_return_address
+  // CIR: [[ARG:%.*]] = cir.const #cir.int<1> : !u32i
+  // CIR: {{%.*}} = cir.return_address([[ARG]])
+
+  // LLVM-LABEL: @test_return_address
+  // LLVM: {{%.*}} = call ptr @llvm.returnaddress(i32 1)
+
+  // OGCG-LABEL: @test_return_address
+  // OGCG: {{%.*}} = call ptr @llvm.returnaddress(i32 1)
+}
+
+extern "C" void *test_frame_address(void) {
+  return __builtin_frame_address(1);
+
+  // CIR-LABEL: test_frame_address
+  // CIR: [[ARG:%.*]] = cir.const #cir.int<1> : !u32i
+  // CIR: {{%.*}} = cir.frame_address([[ARG]])
+
+  // LLVM-LABEL: @test_frame_address
+  // LLVM: {{%.*}} = call ptr @llvm.frameaddress.p0(i32 1)
+
+  // OGCG-LABEL: @test_frame_address
+  // OGCG: {{%.*}} = call ptr @llvm.frameaddress.p0(i32 1)
+}