Index: cfe/trunk/lib/Basic/Targets/ARM.cpp =================================================================== --- cfe/trunk/lib/Basic/Targets/ARM.cpp +++ cfe/trunk/lib/Basic/Targets/ARM.cpp @@ -40,13 +40,14 @@ // so set preferred for small types to 32. if (T.isOSBinFormatMachO()) { resetDataLayout(BigEndian - ? "E-m:o-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64" - : "e-m:o-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"); + ? "E-m:o-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64" + : "e-m:o-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"); } else if (T.isOSWindows()) { assert(!BigEndian && "Windows on ARM does not support big endian"); resetDataLayout("e" "-m:w" "-p:32:32" + "-Fi8" "-i64:64" "-v128:64:128" "-a:0:32" @@ -54,11 +55,11 @@ "-S64"); } else if (T.isOSNaCl()) { assert(!BigEndian && "NaCl on ARM does not support big endian"); - resetDataLayout("e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S128"); + resetDataLayout("e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S128"); } else { resetDataLayout(BigEndian - ? "E-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64" - : "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"); + ? "E-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64" + : "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"); } // FIXME: Enumerated types are variable width in straight AAPCS. @@ -87,17 +88,17 @@ if (T.isOSBinFormatMachO() && IsAAPCS16) { assert(!BigEndian && "AAPCS16 does not support big-endian"); - resetDataLayout("e-m:o-p:32:32-i64:64-a:0:32-n32-S128"); + resetDataLayout("e-m:o-p:32:32-Fi8-i64:64-a:0:32-n32-S128"); } else if (T.isOSBinFormatMachO()) resetDataLayout( BigEndian - ? "E-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" - : "e-m:o-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"); + ? "E-m:o-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" + : "e-m:o-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"); else resetDataLayout( BigEndian - ? "E-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" - : "e-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"); + ? "E-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" + : "e-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32"); // FIXME: Override "preferred align" for double and long long. } @@ -1055,7 +1056,7 @@ this->WCharType = TargetInfo::UnsignedShort; TLSSupported = false; DoubleAlign = LongLongAlign = 64; - resetDataLayout("e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"); + resetDataLayout("e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64"); } void CygwinARMTargetInfo::getTargetDefines(const LangOptions &Opts, Index: cfe/trunk/test/CodeGen/armv7k-abi.c =================================================================== --- cfe/trunk/test/CodeGen/armv7k-abi.c +++ cfe/trunk/test/CodeGen/armv7k-abi.c @@ -4,7 +4,7 @@ // Make sure 64 and 128 bit types are naturally aligned by the v7k ABI: -// CHECK: target datalayout = "e-m:o-p:32:32-i64:64-a:0:32-n32-S128" +// CHECK: target datalayout = "e-m:o-p:32:32-Fi8-i64:64-a:0:32-n32-S128" typedef struct { float arr[4]; Index: cfe/trunk/test/CodeGen/target-data.c =================================================================== --- cfe/trunk/test/CodeGen/target-data.c +++ cfe/trunk/test/CodeGen/target-data.c @@ -96,7 +96,7 @@ // RUN: %clang_cc1 -triple arm-nacl -o - -emit-llvm %s | \ // RUN: FileCheck %s -check-prefix=ARM-NACL -// ARM-NACL: target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S128" +// ARM-NACL: target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S128" // RUN: %clang_cc1 -triple mipsel-nacl -o - -emit-llvm %s | \ // RUN: FileCheck %s -check-prefix=MIPS-NACL @@ -165,19 +165,19 @@ // RUN: %clang_cc1 -triple thumb-unknown-gnueabi -o - -emit-llvm %s | \ // RUN: FileCheck %s -check-prefix=THUMB -// THUMB: target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64" +// THUMB: target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64" // RUN: %clang_cc1 -triple arm-unknown-gnueabi -o - -emit-llvm %s | \ // RUN: FileCheck %s -check-prefix=ARM -// ARM: target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64" +// ARM: target datalayout = "e-m:e-p:32:32-Fi8-i64:64-v128:64:128-a:0:32-n32-S64" // RUN: %clang_cc1 -triple thumb-unknown -o - -emit-llvm -target-abi apcs-gnu \ // RUN: %s | FileCheck %s -check-prefix=THUMB-GNU -// THUMB-GNU: target datalayout = "e-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" +// THUMB-GNU: target datalayout = "e-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" // RUN: %clang_cc1 -triple arm-unknown -o - -emit-llvm -target-abi apcs-gnu \ // RUN: %s | FileCheck %s -check-prefix=ARM-GNU -// ARM-GNU: target datalayout = "e-m:e-p:32:32-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" +// ARM-GNU: target datalayout = "e-m:e-p:32:32-Fi8-f64:32:64-v64:32:64-v128:32:128-a:0:32-n32-S32" // RUN: %clang_cc1 -triple arc-unknown-unknown -o - -emit-llvm %s | \ // RUN: FileCheck %s -check-prefix=ARC Index: llvm/trunk/docs/LangRef.rst =================================================================== --- llvm/trunk/docs/LangRef.rst +++ llvm/trunk/docs/LangRef.rst @@ -2004,6 +2004,14 @@ targets. ``a::`` This specifies the alignment for an object of aggregate type. +``F`` + This specifies the alignment for function pointers. + The options for ```` are: + + * ``i``: The alignment of function pointers is independent of the alignment + of functions, and is a multiple of ````. + * ``n``: The alignment of function pointers is a multiple of the explicit + alignment specified on the function, and is a multiple of ````. ``m:`` If present, specifies that llvm names are mangled in the output. Symbols prefixed with the mangling escape character ``\01`` are passed through Index: llvm/trunk/include/llvm/IR/DataLayout.h =================================================================== --- llvm/trunk/include/llvm/IR/DataLayout.h +++ llvm/trunk/include/llvm/IR/DataLayout.h @@ -108,6 +108,13 @@ /// generating LLVM IR is required to generate the right target data for the /// target being codegen'd to. class DataLayout { +public: + enum class FunctionPtrAlignType { + /// The function pointer alignment is independent of the function alignment. + Independent, + /// The function pointer alignment is a multiple of the function alignment. + MultipleOfFunctionAlign, + }; private: /// Defaults to false. bool BigEndian; @@ -116,6 +123,9 @@ unsigned StackNaturalAlign; unsigned ProgramAddrSpace; + unsigned FunctionPtrAlign; + FunctionPtrAlignType TheFunctionPtrAlignType; + enum ManglingModeT { MM_None, MM_ELF, @@ -199,6 +209,8 @@ BigEndian = DL.isBigEndian(); AllocaAddrSpace = DL.AllocaAddrSpace; StackNaturalAlign = DL.StackNaturalAlign; + FunctionPtrAlign = DL.FunctionPtrAlign; + TheFunctionPtrAlignType = DL.TheFunctionPtrAlignType; ProgramAddrSpace = DL.ProgramAddrSpace; ManglingMode = DL.ManglingMode; LegalIntWidths = DL.LegalIntWidths; @@ -256,6 +268,17 @@ unsigned getStackAlignment() const { return StackNaturalAlign; } unsigned getAllocaAddrSpace() const { return AllocaAddrSpace; } + /// Returns the alignment of function pointers, which may or may not be + /// related to the alignment of functions. + /// \see getFunctionPtrAlignType + unsigned getFunctionPtrAlign() const { return FunctionPtrAlign; } + + /// Return the type of function pointer alignment. + /// \see getFunctionPtrAlign + FunctionPtrAlignType getFunctionPtrAlignType() const { + return TheFunctionPtrAlignType; + } + unsigned getProgramAddressSpace() const { return ProgramAddrSpace; } bool hasMicrosoftFastStdCallMangling() const { Index: llvm/trunk/lib/IR/ConstantFold.cpp =================================================================== --- llvm/trunk/lib/IR/ConstantFold.cpp +++ llvm/trunk/lib/IR/ConstantFold.cpp @@ -26,6 +26,7 @@ #include "llvm/IR/GlobalAlias.h" #include "llvm/IR/GlobalVariable.h" #include "llvm/IR/Instructions.h" +#include "llvm/IR/Module.h" #include "llvm/IR/Operator.h" #include "llvm/IR/PatternMatch.h" #include "llvm/Support/ErrorHandling.h" @@ -1076,10 +1077,29 @@ isa(CE1->getOperand(0))) { GlobalValue *GV = cast(CE1->getOperand(0)); - // Functions are at least 4-byte aligned. - unsigned GVAlign = GV->getAlignment(); - if (isa(GV)) - GVAlign = std::max(GVAlign, 4U); + unsigned GVAlign; + + if (Module *TheModule = GV->getParent()) { + GVAlign = GV->getPointerAlignment(TheModule->getDataLayout()); + + // If the function alignment is not specified then assume that it + // is 4. + // This is dangerous; on x86, the alignment of the pointer + // corresponds to the alignment of the function, but might be less + // than 4 if it isn't explicitly specified. + // However, a fix for this behaviour was reverted because it + // increased code size (see https://reviews.llvm.org/D55115) + // FIXME: This code should be deleted once existing targets have + // appropriate defaults + if (GVAlign == 0U && isa(GV)) + GVAlign = 4U; + } else if (isa(GV)) { + // Without a datalayout we have to assume the worst case: that the + // function pointer isn't aligned at all. + GVAlign = 0U; + } else { + GVAlign = GV->getAlignment(); + } if (GVAlign > 1) { unsigned DstWidth = CI2->getType()->getBitWidth(); Index: llvm/trunk/lib/IR/DataLayout.cpp =================================================================== --- llvm/trunk/lib/IR/DataLayout.cpp +++ llvm/trunk/lib/IR/DataLayout.cpp @@ -184,6 +184,8 @@ AllocaAddrSpace = 0; StackNaturalAlign = 0; ProgramAddrSpace = 0; + FunctionPtrAlign = 0; + TheFunctionPtrAlignType = FunctionPtrAlignType::Independent; ManglingMode = MM_None; NonIntegralAddressSpaces.clear(); @@ -379,6 +381,22 @@ StackNaturalAlign = inBytes(getInt(Tok)); break; } + case 'F': { + switch (Tok.front()) { + case 'i': + TheFunctionPtrAlignType = FunctionPtrAlignType::Independent; + break; + case 'n': + TheFunctionPtrAlignType = FunctionPtrAlignType::MultipleOfFunctionAlign; + break; + default: + report_fatal_error("Unknown function pointer alignment type in " + "datalayout string"); + } + Tok = Tok.substr(1); + FunctionPtrAlign = inBytes(getInt(Tok)); + break; + } case 'P': { // Function address space. ProgramAddrSpace = getAddrSpace(Tok); break; @@ -432,6 +450,8 @@ AllocaAddrSpace == Other.AllocaAddrSpace && StackNaturalAlign == Other.StackNaturalAlign && ProgramAddrSpace == Other.ProgramAddrSpace && + FunctionPtrAlign == Other.FunctionPtrAlign && + TheFunctionPtrAlignType == Other.TheFunctionPtrAlignType && ManglingMode == Other.ManglingMode && LegalIntWidths == Other.LegalIntWidths && Alignments == Other.Alignments && Pointers == Other.Pointers; Index: llvm/trunk/lib/IR/Value.cpp =================================================================== --- llvm/trunk/lib/IR/Value.cpp +++ llvm/trunk/lib/IR/Value.cpp @@ -648,10 +648,16 @@ unsigned Align = 0; if (auto *GO = dyn_cast(this)) { - // Don't make any assumptions about function pointer alignment. Some - // targets use the LSBs to store additional information. - if (isa(GO)) - return 0; + if (isa(GO)) { + switch (DL.getFunctionPtrAlignType()) { + case DataLayout::FunctionPtrAlignType::Independent: + return DL.getFunctionPtrAlign(); + case DataLayout::FunctionPtrAlignType::MultipleOfFunctionAlign: + return std::max(DL.getFunctionPtrAlign(), GO->getAlignment()); + default: + llvm_unreachable("unknown function pointer align type"); + } + } Align = GO->getAlignment(); if (Align == 0) { if (auto *GVar = dyn_cast(GO)) { Index: llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp =================================================================== --- llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp +++ llvm/trunk/lib/Target/ARM/ARMTargetMachine.cpp @@ -141,6 +141,10 @@ // Pointers are 32 bits and aligned to 32 bits. Ret += "-p:32:32"; + // Function pointers are aligned to 8 bits (because the LSB stores the + // ARM/Thumb state). + Ret += "-Fi8"; + // ABIs other than APCS have 64 bit integers with natural alignment. if (ABI != ARMBaseTargetMachine::ARM_ABI_APCS) Ret += "-i64:64"; Index: llvm/trunk/unittests/IR/CMakeLists.txt =================================================================== --- llvm/trunk/unittests/IR/CMakeLists.txt +++ llvm/trunk/unittests/IR/CMakeLists.txt @@ -13,6 +13,7 @@ CFGBuilder.cpp ConstantRangeTest.cpp ConstantsTest.cpp + DataLayoutTest.cpp DebugInfoTest.cpp DebugTypeODRUniquingTest.cpp DominatorTreeTest.cpp Index: llvm/trunk/unittests/IR/ConstantsTest.cpp =================================================================== --- llvm/trunk/unittests/IR/ConstantsTest.cpp +++ llvm/trunk/unittests/IR/ConstantsTest.cpp @@ -475,5 +475,105 @@ ASSERT_EQ(cast(C)->getOpcode(), Instruction::BitCast); } +bool foldFuncPtrAndConstToNull(LLVMContext &Context, Module *TheModule, + uint64_t AndValue, unsigned FunctionAlign = 0) { + Type *VoidType(Type::getVoidTy(Context)); + FunctionType *FuncType(FunctionType::get(VoidType, false)); + Function *Func(Function::Create( + FuncType, GlobalValue::ExternalLinkage, "", TheModule)); + + if (FunctionAlign) Func->setAlignment(FunctionAlign); + + IntegerType *ConstantIntType(Type::getInt32Ty(Context)); + ConstantInt *TheConstant(ConstantInt::get(ConstantIntType, AndValue)); + + Constant *TheConstantExpr( + ConstantExpr::getPtrToInt(Func, ConstantIntType)); + + return ConstantExpr::get(Instruction::And, TheConstantExpr, + TheConstant)->isNullValue(); +} + +TEST(ConstantsTest, FoldFunctionPtrAlignUnknownAnd2) { + LLVMContext Context; + Module TheModule("TestModule", Context); + // When the DataLayout doesn't specify a function pointer alignment we + // assume in this case that it is 4 byte aligned. This is a bug but we can't + // fix it directly because it causes a code size regression on X86. + // FIXME: This test should be changed once existing targets have + // appropriate defaults. See associated FIXME in ConstantFoldBinaryInstruction + ASSERT_TRUE(foldFuncPtrAndConstToNull(Context, &TheModule, 2)); +} + +TEST(ConstantsTest, DontFoldFunctionPtrAlignUnknownAnd4) { + LLVMContext Context; + Module TheModule("TestModule", Context); + ASSERT_FALSE(foldFuncPtrAndConstToNull(Context, &TheModule, 4)); +} + +TEST(ConstantsTest, FoldFunctionPtrAlign4) { + LLVMContext Context; + Module TheModule("TestModule", Context); + const char* AlignmentStrings[] = { "Fi32", "Fn32" }; + + for (unsigned AndValue = 1; AndValue <= 2; ++AndValue) { + for (const char *AlignmentString : AlignmentStrings) { + TheModule.setDataLayout(AlignmentString); + ASSERT_TRUE(foldFuncPtrAndConstToNull(Context, &TheModule, AndValue)); + } + } +} + +TEST(ConstantsTest, DontFoldFunctionPtrAlign1) { + LLVMContext Context; + Module TheModule("TestModule", Context); + const char* AlignmentStrings[] = { "Fi8", "Fn8" }; + + for (const char* AlignmentString : AlignmentStrings) { + TheModule.setDataLayout(AlignmentString); + ASSERT_FALSE(foldFuncPtrAndConstToNull(Context, &TheModule, 2)); + } +} + +TEST(ConstantsTest, FoldFunctionAlign4PtrAlignMultiple) { + LLVMContext Context; + Module TheModule("TestModule", Context); + TheModule.setDataLayout("Fn8"); + ASSERT_TRUE(foldFuncPtrAndConstToNull(Context, &TheModule, 2, 4)); +} + +TEST(ConstantsTest, DontFoldFunctionAlign4PtrAlignIndependent) { + LLVMContext Context; + Module TheModule("TestModule", Context); + TheModule.setDataLayout("Fi8"); + ASSERT_FALSE(foldFuncPtrAndConstToNull(Context, &TheModule, 2, 4)); +} + +TEST(ConstantsTest, DontFoldFunctionPtrIfNoModule) { + LLVMContext Context; + // Even though the function is explicitly 4 byte aligned, in the absence of a + // DataLayout we can't assume that the function pointer is aligned. + ASSERT_FALSE(foldFuncPtrAndConstToNull(Context, nullptr, 2, 4)); +} + +TEST(ConstantsTest, FoldGlobalVariablePtr) { + LLVMContext Context; + + + IntegerType *IntType(Type::getInt32Ty(Context)); + + GlobalVariable Global(IntType, true, GlobalValue::ExternalLinkage); + + Global.setAlignment(4); + + ConstantInt *TheConstant(ConstantInt::get(IntType, 2)); + + Constant *TheConstantExpr( + ConstantExpr::getPtrToInt(&Global, IntType)); + + ASSERT_TRUE(ConstantExpr::get( \ + Instruction::And, TheConstantExpr, TheConstant)->isNullValue()); +} + } // end anonymous namespace } // end namespace llvm Index: llvm/trunk/unittests/IR/DataLayoutTest.cpp =================================================================== --- llvm/trunk/unittests/IR/DataLayoutTest.cpp +++ llvm/trunk/unittests/IR/DataLayoutTest.cpp @@ -0,0 +1,47 @@ +//===- ConstantRangeTest.cpp - ConstantRange tests ------------------------===// +// +// 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 +// +//===----------------------------------------------------------------------===// + +#include "llvm/IR/DataLayout.h" +#include "gtest/gtest.h" + +using namespace llvm; + +namespace { + +TEST(DataLayoutTest, FunctionPtrAlign) { + EXPECT_EQ(0U, DataLayout("").getFunctionPtrAlign()); + EXPECT_EQ(1U, DataLayout("Fi8").getFunctionPtrAlign()); + EXPECT_EQ(2U, DataLayout("Fi16").getFunctionPtrAlign()); + EXPECT_EQ(4U, DataLayout("Fi32").getFunctionPtrAlign()); + EXPECT_EQ(8U, DataLayout("Fi64").getFunctionPtrAlign()); + EXPECT_EQ(1U, DataLayout("Fn8").getFunctionPtrAlign()); + EXPECT_EQ(2U, DataLayout("Fn16").getFunctionPtrAlign()); + EXPECT_EQ(4U, DataLayout("Fn32").getFunctionPtrAlign()); + EXPECT_EQ(8U, DataLayout("Fn64").getFunctionPtrAlign()); + EXPECT_EQ(DataLayout::FunctionPtrAlignType::Independent, \ + DataLayout("").getFunctionPtrAlignType()); + EXPECT_EQ(DataLayout::FunctionPtrAlignType::Independent, \ + DataLayout("Fi8").getFunctionPtrAlignType()); + EXPECT_EQ(DataLayout::FunctionPtrAlignType::MultipleOfFunctionAlign, \ + DataLayout("Fn8").getFunctionPtrAlignType()); + EXPECT_EQ(DataLayout("Fi8"), DataLayout("Fi8")); + EXPECT_NE(DataLayout("Fi8"), DataLayout("Fi16")); + EXPECT_NE(DataLayout("Fi8"), DataLayout("Fn8")); + + DataLayout a(""), b("Fi8"), c("Fn8"); + EXPECT_NE(a, b); + EXPECT_NE(a, c); + EXPECT_NE(b, c); + + a = b; + EXPECT_EQ(a, b); + a = c; + EXPECT_EQ(a, c); +} + +} // anonymous namespace Index: llvm/trunk/unittests/IR/FunctionTest.cpp =================================================================== --- llvm/trunk/unittests/IR/FunctionTest.cpp +++ llvm/trunk/unittests/IR/FunctionTest.cpp @@ -129,4 +129,29 @@ EXPECT_TRUE(F->hasSection()); } +TEST(FunctionTest, GetPointerAlignment) { + LLVMContext Context; + Type *VoidType(Type::getVoidTy(Context)); + FunctionType *FuncType(FunctionType::get(VoidType, false)); + Function *Func = Function::Create( + FuncType, GlobalValue::ExternalLinkage); + EXPECT_EQ(0U, Func->getPointerAlignment(DataLayout(""))); + EXPECT_EQ(1U, Func->getPointerAlignment(DataLayout("Fi8"))); + EXPECT_EQ(1U, Func->getPointerAlignment(DataLayout("Fn8"))); + EXPECT_EQ(2U, Func->getPointerAlignment(DataLayout("Fi16"))); + EXPECT_EQ(2U, Func->getPointerAlignment(DataLayout("Fn16"))); + EXPECT_EQ(4U, Func->getPointerAlignment(DataLayout("Fi32"))); + EXPECT_EQ(4U, Func->getPointerAlignment(DataLayout("Fn32"))); + + Func->setAlignment(4U); + + EXPECT_EQ(0U, Func->getPointerAlignment(DataLayout(""))); + EXPECT_EQ(1U, Func->getPointerAlignment(DataLayout("Fi8"))); + EXPECT_EQ(4U, Func->getPointerAlignment(DataLayout("Fn8"))); + EXPECT_EQ(2U, Func->getPointerAlignment(DataLayout("Fi16"))); + EXPECT_EQ(4U, Func->getPointerAlignment(DataLayout("Fn16"))); + EXPECT_EQ(4U, Func->getPointerAlignment(DataLayout("Fi32"))); + EXPECT_EQ(4U, Func->getPointerAlignment(DataLayout("Fn32"))); +} + } // end namespace