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https://github.com/Gericom/teak-llvm.git
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acd7d2b00b
The change cleans up and unifies the handling of relocation entries in WasmObjectWriter. Type index relocation no longer need to be handled separately. The only externally visible change should be that type index relocations are no longer grouped at the end. Differential Revision: https://reviews.llvm.org/D33918 llvm-svn: 304816
100 lines
3.6 KiB
C++
100 lines
3.6 KiB
C++
//===-- WebAssemblyWasmObjectWriter.cpp - WebAssembly Wasm Writer ---------===//
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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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///
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/// \file
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/// \brief This file handles Wasm-specific object emission, converting LLVM's
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/// internal fixups into the appropriate relocations.
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///
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/WebAssemblyFixupKinds.h"
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#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCSymbolWasm.h"
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#include "llvm/MC/MCWasmObjectWriter.h"
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#include "llvm/Support/Casting.h"
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#include "llvm/Support/ErrorHandling.h"
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#include "llvm/Support/Wasm.h"
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using namespace llvm;
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namespace {
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class WebAssemblyWasmObjectWriter final : public MCWasmObjectTargetWriter {
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public:
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explicit WebAssemblyWasmObjectWriter(bool Is64Bit);
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private:
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unsigned getRelocType(MCContext &Ctx, const MCValue &Target,
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const MCFixup &Fixup, bool IsPCRel) const override;
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};
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} // end anonymous namespace
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WebAssemblyWasmObjectWriter::WebAssemblyWasmObjectWriter(bool Is64Bit)
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: MCWasmObjectTargetWriter(Is64Bit) {}
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// Test whether the given expression computes a function address.
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static bool IsFunctionExpr(const MCExpr *Expr) {
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if (const MCSymbolRefExpr *SyExp =
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dyn_cast<MCSymbolRefExpr>(Expr))
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return cast<MCSymbolWasm>(SyExp->getSymbol()).isFunction();
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if (const MCBinaryExpr *BinOp =
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dyn_cast<MCBinaryExpr>(Expr))
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return IsFunctionExpr(BinOp->getLHS()) != IsFunctionExpr(BinOp->getRHS());
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if (const MCUnaryExpr *UnOp =
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dyn_cast<MCUnaryExpr>(Expr))
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return IsFunctionExpr(UnOp->getSubExpr());
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return false;
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}
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static bool IsFunctionType(const MCValue &Target) {
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const MCSymbolRefExpr *RefA = Target.getSymA();
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return RefA && RefA->getKind() == MCSymbolRefExpr::VK_WebAssembly_TYPEINDEX;
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}
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unsigned WebAssemblyWasmObjectWriter::getRelocType(MCContext &Ctx,
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const MCValue &Target,
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const MCFixup &Fixup,
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bool IsPCRel) const {
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// WebAssembly functions are not allocated in the data address space. To
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// resolve a pointer to a function, we must use a special relocation type.
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bool IsFunction = IsFunctionExpr(Fixup.getValue());
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assert(!IsPCRel);
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switch (unsigned(Fixup.getKind())) {
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case WebAssembly::fixup_code_sleb128_i32:
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if (IsFunction)
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return wasm::R_WEBASSEMBLY_TABLE_INDEX_SLEB;
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return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_SLEB;
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case WebAssembly::fixup_code_sleb128_i64:
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llvm_unreachable("fixup_sleb128_i64 not implemented yet");
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case WebAssembly::fixup_code_uleb128_i32:
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if (IsFunctionType(Target))
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return wasm::R_WEBASSEMBLY_TYPE_INDEX_LEB;
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if (IsFunction)
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return wasm::R_WEBASSEMBLY_FUNCTION_INDEX_LEB;
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return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_LEB;
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case FK_Data_4:
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if (IsFunction)
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return wasm::R_WEBASSEMBLY_TABLE_INDEX_I32;
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return wasm::R_WEBASSEMBLY_GLOBAL_ADDR_I32;
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case FK_Data_8:
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llvm_unreachable("FK_Data_8 not implemented yet");
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default:
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llvm_unreachable("unimplemented fixup kind");
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}
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}
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MCObjectWriter *llvm::createWebAssemblyWasmObjectWriter(raw_pwrite_stream &OS,
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bool Is64Bit) {
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MCWasmObjectTargetWriter *MOTW = new WebAssemblyWasmObjectWriter(Is64Bit);
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return createWasmObjectWriter(MOTW, OS);
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}
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