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ffdf511cf4
This patch adds support for some new relocation models to the ARM backend: * Read-only position independence (ROPI): Code and read-only data is accessed PC-relative. The offsets between all code and RO data sections are known at static link time. This does not affect read-write data. * Read-write position independence (RWPI): Read-write data is accessed relative to the static base register (r9). The offsets between all writeable data sections are known at static link time. This does not affect read-only data. These two modes are independent (they specify how different objects should be addressed), so they can be used individually or together. They are otherwise the same as the "static" relocation model, and are not compatible with SysV-style PIC using a global offset table. These modes are normally used by bare-metal systems or systems with small real-time operating systems. They are designed to avoid the need for a dynamic linker, the only initialisation required is setting r9 to an appropriate value for RWPI code. I have only added support to SelectionDAG, not FastISel, because FastISel is currently disabled for bare-metal targets where these modes would be used. Differential Revision: https://reviews.llvm.org/D23195 llvm-svn: 278015
63 lines
1.4 KiB
C++
63 lines
1.4 KiB
C++
//===-- llvm/Support/CodeGen.h - CodeGen Concepts ---------------*- C++ -*-===//
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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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// This file define some types which define code generation concepts. For
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// example, relocation model.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_SUPPORT_CODEGEN_H
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#define LLVM_SUPPORT_CODEGEN_H
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namespace llvm {
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// Relocation model types.
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namespace Reloc {
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enum Model { Static, PIC_, DynamicNoPIC, ROPI, RWPI, ROPI_RWPI };
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}
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// Code model types.
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namespace CodeModel {
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// Sync changes with CodeGenCWrappers.h.
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enum Model { Default, JITDefault, Small, Kernel, Medium, Large };
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}
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namespace PICLevel {
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// This is used to map -fpic/-fPIC.
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enum Level { NotPIC=0, SmallPIC=1, BigPIC=2 };
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}
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namespace PIELevel {
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enum Level { Default=0, Small=1, Large=2 };
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}
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// TLS models.
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namespace TLSModel {
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enum Model {
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GeneralDynamic,
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LocalDynamic,
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InitialExec,
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LocalExec
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};
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}
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// Code generation optimization level.
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namespace CodeGenOpt {
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enum Level {
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None, // -O0
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Less, // -O1
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Default, // -O2, -Os
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Aggressive // -O3
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};
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}
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} // end llvm namespace
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#endif
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