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round 4: AArch64 ABI lowering cir.var_arg, squashed related commits
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clang/lib/CIR/Dialect/Transforms/LoweringPrepareAArch64CXXABI.cpp
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| //====- LoweringPrepareArm64CXXABI.cpp - Arm64 ABI specific code -----====// | ||
| // | ||
| // Part of the LLVM Project, | ||
| // under the Apache License v2.0 with LLVM Exceptions. | ||
| // See https://llvm.org/LICENSE.txt for license information. | ||
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception | ||
| // | ||
| //===------------------------------------------------------------------===// | ||
| // | ||
| // This file provides ARM64 C++ ABI specific code that is used during LLVMIR | ||
| // lowering prepare. | ||
| // | ||
| //===------------------------------------------------------------------===// | ||
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| #include "../IR/MissingFeatures.h" | ||
| #include "../../CodeGen/TargetInfo.h" | ||
| #include "LoweringPrepareItaniumCXXABI.h" | ||
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| #include <assert.h> | ||
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| using cir::LoweringPrepareCXXABI; | ||
| using cir::MissingFeatures; | ||
| using cir::AArch64ABIKind; | ||
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| using namespace mlir; | ||
| using namespace mlir::cir; | ||
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| namespace { | ||
| class LoweringPrepareAArch64CXXABI : public LoweringPrepareItaniumCXXABI { | ||
| public: | ||
| LoweringPrepareAArch64CXXABI(AArch64ABIKind k) : Kind(k) {} | ||
| mlir::Value lowerVAArg(CIRBaseBuilderTy &builder, | ||
| mlir::cir::VAArgOp op) override; | ||
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| private: | ||
| AArch64ABIKind Kind; | ||
| mlir::Value lowerAAPCSVAArg(CIRBaseBuilderTy &builder, mlir::cir::VAArgOp op); | ||
| }; | ||
| } // namespace | ||
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| LoweringPrepareCXXABI * | ||
| LoweringPrepareCXXABI::createAArch64ABI(AArch64ABIKind k) { | ||
| return new LoweringPrepareAArch64CXXABI(k); | ||
| } | ||
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| mlir::Value | ||
| LoweringPrepareAArch64CXXABI::lowerAAPCSVAArg(CIRBaseBuilderTy &builder, | ||
| mlir::cir::VAArgOp op) { | ||
| auto loc = op->getLoc(); | ||
| auto valist = op->getOperand(0); | ||
| auto opResTy = op.getType(); | ||
| // front end should not produce non-scalar type of VAArgOp | ||
| bool isSupportedType = | ||
| opResTy.isa<mlir::cir::IntType, mlir::cir::SingleType, | ||
| mlir::cir::PointerType, mlir::cir::BoolType, | ||
| mlir::cir::DoubleType>(); | ||
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| // Homogenous Aggregate type not supported and indirect arg | ||
| // passing not supported yet. And for these supported types, | ||
| // we should not have alignment greater than 8 problem. | ||
| assert(isSupportedType); | ||
| assert(!MissingFeatures::handleAArch64Indirect()); | ||
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| bool isFloatingType = | ||
| opResTy.isa<mlir::cir::SingleType, mlir::cir::DoubleType>(); | ||
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| // The AArch64 va_list type and handling is specified in the Procedure Call | ||
| // Standard, section B.4: | ||
| // | ||
| // struct { | ||
| // void *__stack; | ||
| // void *__gr_top; | ||
| // void *__vr_top; | ||
| // int __gr_offs; | ||
| // int __vr_offs; | ||
| // }; | ||
| auto curInsertionP = builder.saveInsertionPoint(); | ||
| auto currentBlock = builder.getInsertionBlock(); | ||
| auto boolTy = builder.getBoolTy(); | ||
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| auto maybeRegBlock = builder.createBlock(builder.getBlock()->getParent()); | ||
| auto inRegBlock = builder.createBlock(builder.getBlock()->getParent()); | ||
| auto onStackBlock = builder.createBlock(builder.getBlock()->getParent()); | ||
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| //======================================= | ||
| // Find out where argument was passed | ||
| //======================================= | ||
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| // If v/gr_offs >= 0 we're already using the stack for this type of | ||
| // argument. We don't want to keep updating reg_offs (in case it overflows, | ||
| // though anyone passing 2GB of arguments, each at most 16 bytes, deserves | ||
| // whatever they get). | ||
| builder.restoreInsertionPoint(curInsertionP); | ||
| // 3 is the field number of __gr_offs, 4 is the field number of __vr_offs | ||
| auto offsP = builder.createGetMemberOp(loc, valist, | ||
| isFloatingType ? "vr_offs" : "gr_offs", | ||
| isFloatingType ? 4 : 3); | ||
| auto offs = builder.create<mlir::cir::LoadOp>(loc, offsP); | ||
| auto zeroValue = builder.create<mlir::cir::ConstantOp>( | ||
| loc, offs.getType(), mlir::cir::IntAttr::get(offs.getType(), 0)); | ||
| auto cmpRes = builder.create<mlir::cir::CmpOp>(loc, boolTy, CmpOpKind::ge, | ||
| offs, zeroValue); | ||
| builder.create<mlir::cir::BrCondOp>(loc, cmpRes, onStackBlock, maybeRegBlock); | ||
| auto newEndBlock = currentBlock->splitBlock(op); | ||
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| // maybeRegBlock updates the gr_offs/vr_offs pointer for next call to va_arg | ||
| // on this va_list. The fact that this is done unconditionally reflects the | ||
| // fact that allocating an argument to the stack also uses up all the | ||
| // remaining registers of the appropriate kind. | ||
| builder.setInsertionPointToEnd(maybeRegBlock); | ||
| auto boundaryValue = builder.create<mlir::cir::ConstantOp>( | ||
| loc, offs.getType(), | ||
| mlir::cir::IntAttr::get(offs.getType(), isFloatingType ? 16 : 8)); | ||
| auto newRegsOffs = builder.create<mlir::cir::BinOp>( | ||
| loc, offs.getType(), mlir::cir::BinOpKind::Add, offs, boundaryValue); | ||
| builder.createStore(loc, newRegsOffs, offsP); | ||
| // Now we're in a position to decide whether this argument really was in | ||
| // registers or not. | ||
| auto maybeRegCmpRes = builder.create<mlir::cir::CmpOp>( | ||
| loc, boolTy, CmpOpKind::le, newRegsOffs, zeroValue); | ||
| builder.create<mlir::cir::BrCondOp>(loc, maybeRegCmpRes, inRegBlock, | ||
| onStackBlock); | ||
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| //======================================= | ||
| // Argument was on the stack | ||
| //======================================= | ||
| builder.setInsertionPointToEnd(onStackBlock); | ||
| auto stackP = builder.createGetMemberOp(loc, valist, "stack", 0); | ||
| // On big-endian platforms, the value will be right-aligned in its stack slot. | ||
| assert(!MissingFeatures::handleBigEndian()); | ||
| auto stack = builder.create<mlir::cir::LoadOp>(loc, stackP); | ||
| auto ptrDiffTy = | ||
| mlir::cir::IntType::get(builder.getContext(), 64, /*signed=*/false); | ||
| auto eight = builder.create<mlir::cir::ConstantOp>( | ||
| loc, ptrDiffTy, mlir::cir::IntAttr::get(ptrDiffTy, 8)); | ||
| auto i8Ty = IntegerType::get(builder.getContext(), 8); | ||
| auto i8PtrTy = PointerType::get(builder.getContext(), i8Ty); | ||
| auto castStack = builder.createBitcast(stack, i8PtrTy); | ||
| // Write the new value of __stack for the next call to va_arg | ||
| auto newStackAsi8Ptr = builder.create<mlir::cir::PtrStrideOp>( | ||
| loc, castStack.getType(), castStack, eight); | ||
| auto newStack = builder.createBitcast(newStackAsi8Ptr, stack.getType()); | ||
| builder.createStore(loc, newStack, stackP); | ||
| builder.create<mlir::cir::BrOp>(loc, mlir::ValueRange{stack}, newEndBlock); | ||
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| //======================================= | ||
| // Argument was in registers | ||
| //======================================= | ||
| // Now we emit the code for if the argument was originally passed in | ||
| // registers. First start the appropriate block: | ||
| builder.setInsertionPointToEnd(inRegBlock); | ||
| auto regTopP = builder.createGetMemberOp(loc, valist, | ||
| isFloatingType ? "vr_top" : "gr_top", | ||
| isFloatingType ? 2 : 1); | ||
| auto regTop = builder.create<mlir::cir::LoadOp>(loc, regTopP); | ||
| auto castRegTop = builder.createBitcast(regTop, i8PtrTy); | ||
| // On big-endian platforms, the value will be right-aligned in its stack slot. | ||
| assert(!MissingFeatures::handleBigEndian()); | ||
| auto resAsInt8P = builder.create<mlir::cir::PtrStrideOp>( | ||
| loc, castRegTop.getType(), castRegTop, offs); | ||
| auto resAsVoidP = builder.createBitcast(resAsInt8P, regTop.getType()); | ||
| builder.create<mlir::cir::BrOp>(loc, mlir::ValueRange{resAsVoidP}, | ||
| newEndBlock); | ||
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| // generate additional instructions for end block | ||
| builder.setInsertionPoint(op); | ||
| newEndBlock->addArgument(stack.getType(), loc); | ||
| auto resP = newEndBlock->getArgument(0); | ||
| assert(resP.getType().isa<mlir::cir::PointerType>()); | ||
| auto opResPTy = PointerType::get(builder.getContext(), opResTy); | ||
| auto castResP = builder.createBitcast(resP, opResPTy); | ||
| auto res = builder.create<mlir::cir::LoadOp>(loc, castResP); | ||
| return res.getResult(); | ||
| } | ||
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| mlir::Value LoweringPrepareAArch64CXXABI::lowerVAArg(CIRBaseBuilderTy &builder, | ||
| mlir::cir::VAArgOp op) { | ||
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| if (Kind == AArch64ABIKind::AAPCS) { | ||
| return lowerAAPCSVAArg(builder, op); | ||
| } | ||
| assert(0 && "unsupported AArch64 CXX ABI"); | ||
| } |
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