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083db8b72c
This is the first of a number of changes designed to generalise MCWin64EHInstruction to support different target architectures. An ordered set (vector) of these instructions is saved per frame to permit the emission of information for Windows NT style unwinding. The only bit of information which is actually target specific here is the Opcode for the unwinding bytecode. The remainder of the information is simply generic information that is relevant to the Windows NT unwinding model. Remove the accessors for the fields, making them const and public instead. Sink the knowledge of the alias'ed name into the single source and sink a single-use check method into the use. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212914 91177308-0d34-0410-b5e6-96231b3b80d8
291 lines
10 KiB
C++
291 lines
10 KiB
C++
//===- lib/MC/MCWin64EH.cpp - MCWin64EH implementation --------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/MC/MCWin64EH.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/MC/MCContext.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCObjectFileInfo.h"
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#include "llvm/MC/MCSectionCOFF.h"
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#include "llvm/MC/MCStreamer.h"
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#include "llvm/MC/MCSymbol.h"
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namespace llvm {
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// NOTE: All relocations generated here are 4-byte image-relative.
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static uint8_t CountOfUnwindCodes(std::vector<MCWin64EHInstruction> &Insns) {
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uint8_t Count = 0;
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for (const auto &I : Insns) {
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switch (I.Operation) {
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case Win64EH::UOP_PushNonVol:
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case Win64EH::UOP_AllocSmall:
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case Win64EH::UOP_SetFPReg:
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case Win64EH::UOP_PushMachFrame:
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Count += 1;
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break;
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case Win64EH::UOP_SaveNonVol:
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case Win64EH::UOP_SaveXMM128:
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Count += 2;
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break;
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case Win64EH::UOP_SaveNonVolBig:
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case Win64EH::UOP_SaveXMM128Big:
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Count += 3;
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break;
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case Win64EH::UOP_AllocLarge:
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Count += (I.Offset > 512 * 1024 - 8) ? 3 : 2;
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break;
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}
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}
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return Count;
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}
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static void EmitAbsDifference(MCStreamer &Streamer, const MCSymbol *LHS,
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const MCSymbol *RHS) {
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MCContext &Context = Streamer.getContext();
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const MCExpr *Diff =
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MCBinaryExpr::CreateSub(MCSymbolRefExpr::Create(LHS, Context),
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MCSymbolRefExpr::Create(RHS, Context), Context);
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Streamer.EmitAbsValue(Diff, 1);
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}
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static void EmitUnwindCode(MCStreamer &streamer, MCSymbol *begin,
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MCWin64EHInstruction &inst) {
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uint8_t b2;
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uint16_t w;
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b2 = (inst.Operation & 0x0F);
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switch (inst.Operation) {
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case Win64EH::UOP_PushNonVol:
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EmitAbsDifference(streamer, inst.Label, begin);
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b2 |= (inst.Register & 0x0F) << 4;
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streamer.EmitIntValue(b2, 1);
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break;
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case Win64EH::UOP_AllocLarge:
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EmitAbsDifference(streamer, inst.Label, begin);
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if (inst.Offset > 512 * 1024 - 8) {
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b2 |= 0x10;
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streamer.EmitIntValue(b2, 1);
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w = inst.Offset & 0xFFF8;
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streamer.EmitIntValue(w, 2);
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w = inst.Offset >> 16;
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} else {
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streamer.EmitIntValue(b2, 1);
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w = inst.Offset >> 3;
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}
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streamer.EmitIntValue(w, 2);
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break;
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case Win64EH::UOP_AllocSmall:
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b2 |= (((inst.Offset - 8) >> 3) & 0x0F) << 4;
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EmitAbsDifference(streamer, inst.Label, begin);
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streamer.EmitIntValue(b2, 1);
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break;
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case Win64EH::UOP_SetFPReg:
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EmitAbsDifference(streamer, inst.Label, begin);
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streamer.EmitIntValue(b2, 1);
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break;
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case Win64EH::UOP_SaveNonVol:
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case Win64EH::UOP_SaveXMM128:
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b2 |= (inst.Register & 0x0F) << 4;
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EmitAbsDifference(streamer, inst.Label, begin);
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streamer.EmitIntValue(b2, 1);
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w = inst.Offset >> 3;
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if (inst.Operation == Win64EH::UOP_SaveXMM128)
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w >>= 1;
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streamer.EmitIntValue(w, 2);
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break;
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case Win64EH::UOP_SaveNonVolBig:
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case Win64EH::UOP_SaveXMM128Big:
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b2 |= (inst.Register & 0x0F) << 4;
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EmitAbsDifference(streamer, inst.Label, begin);
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streamer.EmitIntValue(b2, 1);
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if (inst.Operation == Win64EH::UOP_SaveXMM128Big)
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w = inst.Offset & 0xFFF0;
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else
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w = inst.Offset & 0xFFF8;
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streamer.EmitIntValue(w, 2);
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w = inst.Offset >> 16;
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streamer.EmitIntValue(w, 2);
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break;
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case Win64EH::UOP_PushMachFrame:
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if (inst.Offset == 1)
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b2 |= 0x10;
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EmitAbsDifference(streamer, inst.Label, begin);
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streamer.EmitIntValue(b2, 1);
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break;
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}
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}
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static void EmitSymbolRefWithOfs(MCStreamer &streamer,
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const MCSymbol *Base,
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const MCSymbol *Other) {
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MCContext &Context = streamer.getContext();
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const MCSymbolRefExpr *BaseRef = MCSymbolRefExpr::Create(Base, Context);
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const MCSymbolRefExpr *OtherRef = MCSymbolRefExpr::Create(Other, Context);
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const MCExpr *Ofs = MCBinaryExpr::CreateSub(OtherRef, BaseRef, Context);
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const MCSymbolRefExpr *BaseRefRel = MCSymbolRefExpr::Create(Base,
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MCSymbolRefExpr::VK_COFF_IMGREL32,
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Context);
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streamer.EmitValue(MCBinaryExpr::CreateAdd(BaseRefRel, Ofs, Context), 4);
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}
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static void EmitRuntimeFunction(MCStreamer &streamer,
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const MCWinFrameInfo *info) {
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MCContext &context = streamer.getContext();
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streamer.EmitValueToAlignment(4);
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EmitSymbolRefWithOfs(streamer, info->Function, info->Begin);
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EmitSymbolRefWithOfs(streamer, info->Function, info->End);
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streamer.EmitValue(MCSymbolRefExpr::Create(info->Symbol,
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MCSymbolRefExpr::VK_COFF_IMGREL32,
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context), 4);
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}
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static void EmitUnwindInfo(MCStreamer &streamer, MCWinFrameInfo *info) {
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// If this UNWIND_INFO already has a symbol, it's already been emitted.
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if (info->Symbol) return;
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MCContext &context = streamer.getContext();
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streamer.EmitValueToAlignment(4);
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info->Symbol = context.CreateTempSymbol();
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streamer.EmitLabel(info->Symbol);
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// Upper 3 bits are the version number (currently 1).
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uint8_t flags = 0x01;
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if (info->ChainedParent)
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flags |= Win64EH::UNW_ChainInfo << 3;
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else {
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if (info->HandlesUnwind)
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flags |= Win64EH::UNW_TerminateHandler << 3;
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if (info->HandlesExceptions)
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flags |= Win64EH::UNW_ExceptionHandler << 3;
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}
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streamer.EmitIntValue(flags, 1);
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if (info->PrologEnd)
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EmitAbsDifference(streamer, info->PrologEnd, info->Begin);
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else
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streamer.EmitIntValue(0, 1);
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uint8_t numCodes = CountOfUnwindCodes(info->Instructions);
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streamer.EmitIntValue(numCodes, 1);
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uint8_t frame = 0;
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if (info->LastFrameInst >= 0) {
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MCWin64EHInstruction &frameInst = info->Instructions[info->LastFrameInst];
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assert(frameInst.Operation == Win64EH::UOP_SetFPReg);
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frame = (frameInst.Register & 0x0F) | (frameInst.Offset & 0xF0);
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}
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streamer.EmitIntValue(frame, 1);
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// Emit unwind instructions (in reverse order).
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uint8_t numInst = info->Instructions.size();
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for (uint8_t c = 0; c < numInst; ++c) {
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MCWin64EHInstruction inst = info->Instructions.back();
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info->Instructions.pop_back();
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EmitUnwindCode(streamer, info->Begin, inst);
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}
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// For alignment purposes, the instruction array will always have an even
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// number of entries, with the final entry potentially unused (in which case
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// the array will be one longer than indicated by the count of unwind codes
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// field).
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if (numCodes & 1) {
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streamer.EmitIntValue(0, 2);
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}
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if (flags & (Win64EH::UNW_ChainInfo << 3))
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EmitRuntimeFunction(streamer, info->ChainedParent);
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else if (flags &
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((Win64EH::UNW_TerminateHandler|Win64EH::UNW_ExceptionHandler) << 3))
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streamer.EmitValue(MCSymbolRefExpr::Create(info->ExceptionHandler,
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MCSymbolRefExpr::VK_COFF_IMGREL32,
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context), 4);
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else if (numCodes == 0) {
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// The minimum size of an UNWIND_INFO struct is 8 bytes. If we're not
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// a chained unwind info, if there is no handler, and if there are fewer
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// than 2 slots used in the unwind code array, we have to pad to 8 bytes.
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streamer.EmitIntValue(0, 4);
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}
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}
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StringRef MCWin64EHUnwindEmitter::GetSectionSuffix(const MCSymbol *func) {
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if (!func || !func->isInSection()) return "";
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const MCSection *section = &func->getSection();
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const MCSectionCOFF *COFFSection;
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if ((COFFSection = dyn_cast<MCSectionCOFF>(section))) {
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StringRef name = COFFSection->getSectionName();
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size_t dollar = name.find('$');
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size_t dot = name.find('.', 1);
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if (dollar == StringRef::npos && dot == StringRef::npos)
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return "";
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if (dot == StringRef::npos)
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return name.substr(dollar);
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if (dollar == StringRef::npos || dot < dollar)
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return name.substr(dot);
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return name.substr(dollar);
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}
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return "";
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}
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static const MCSection *getWin64EHTableSection(StringRef suffix,
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MCContext &context) {
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if (suffix == "")
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return context.getObjectFileInfo()->getXDataSection();
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return context.getCOFFSection((".xdata"+suffix).str(),
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COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
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COFF::IMAGE_SCN_MEM_READ,
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SectionKind::getDataRel());
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}
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static const MCSection *getWin64EHFuncTableSection(StringRef suffix,
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MCContext &context) {
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if (suffix == "")
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return context.getObjectFileInfo()->getPDataSection();
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return context.getCOFFSection((".pdata"+suffix).str(),
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COFF::IMAGE_SCN_CNT_INITIALIZED_DATA |
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COFF::IMAGE_SCN_MEM_READ,
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SectionKind::getDataRel());
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}
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void MCWin64EHUnwindEmitter::EmitUnwindInfo(MCStreamer &streamer,
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MCWinFrameInfo *info) {
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// Switch sections (the static function above is meant to be called from
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// here and from Emit().
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MCContext &context = streamer.getContext();
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const MCSection *xdataSect =
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getWin64EHTableSection(GetSectionSuffix(info->Function), context);
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streamer.SwitchSection(xdataSect);
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llvm::EmitUnwindInfo(streamer, info);
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}
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void MCWin64EHUnwindEmitter::Emit(MCStreamer &Streamer) {
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MCContext &Context = Streamer.getContext();
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// Emit the unwind info structs first.
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for (const auto &CFI : Streamer.getWinFrameInfos()) {
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const MCSection *XData =
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getWin64EHTableSection(GetSectionSuffix(CFI->Function), Context);
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Streamer.SwitchSection(XData);
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EmitUnwindInfo(Streamer, CFI);
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}
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// Now emit RUNTIME_FUNCTION entries.
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for (const auto &CFI : Streamer.getWinFrameInfos()) {
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const MCSection *PData =
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getWin64EHFuncTableSection(GetSectionSuffix(CFI->Function), Context);
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Streamer.SwitchSection(PData);
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EmitRuntimeFunction(Streamer, CFI);
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}
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}
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} // End of namespace llvm
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