MC: Support COFF image-relative MCSymbolRefs
Add support for the COFF relocation types IMAGE_REL_I386_DIR32NB and
IMAGE_REL_AMD64_ADDR32NB for 32- and 64-bit respectively. These are
similar to normal 4-byte relocations except that they do not include
the base address of the image.
Image-relative relocations are used for debug information (32-bit) and
SEH unwind tables (64-bit).
A new MCSymbolRef variant called 'VK_COFF_IMGREL32' is introduced to
specify such relocations. For AT&T assembly, this variant can be accessed
using the symbol suffix '@imgrel'.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@179240 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/Extensions.rst b/docs/Extensions.rst
new file mode 100644
index 0000000..062804a
--- /dev/null
+++ b/docs/Extensions.rst
@@ -0,0 +1,39 @@
+===============
+LLVM Extensions
+===============
+
+.. contents::
+ :local:
+ :depth: 1
+
+.. toctree::
+ :hidden:
+
+Introduction
+============
+
+This document describes extensions to tools and formats LLVM seeks compatibility
+with.
+
+Machine-specific Assembly Syntax
+================================
+
+X86/COFF-Dependent
+------------------
+
+The following additional relocation type is supported:
+
+**@IMGREL** (AT&T syntax only) generates an image-relative relocation that
+corresponds to the COFF relocation types ``IMAGE_REL_I386_DIR32NB`` (32-bit) or
+``IMAGE_REL_AMD64_ADDR32NB`` (64-bit).
+
+.. code-block:: gas
+
+ .text
+ fun:
+ mov foo@IMGREL(%ebx, %ecx, 4), %eax
+
+ .section .pdata
+ .long fun@IMGREL
+ .long (fun@imgrel + 0x3F)
+ .long $unwind$fun@imgrel
diff --git a/docs/index.rst b/docs/index.rst
index c3bb808..6b182da 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -160,6 +160,7 @@
ExtendingLLVM
HowToSetUpLLVMStyleRTTI
ProgrammersManual
+ Extensions
:doc:`LLVM Language Reference Manual <LangRef>`
Defines the LLVM intermediate representation and the assembly form of the
@@ -172,6 +173,9 @@
Introduction to the general layout of the LLVM sourcebase, important classes
and APIs, and some tips & tricks.
+:doc:`Extensions`
+ LLVM-specific extensions to tools and formats LLVM seeks compatibility with.
+
:doc:`CommandLine`
Provides information on using the command line parsing library.
diff --git a/include/llvm/MC/MCExpr.h b/include/llvm/MC/MCExpr.h
index b5bfed1..a2c5bd3 100644
--- a/include/llvm/MC/MCExpr.h
+++ b/include/llvm/MC/MCExpr.h
@@ -216,7 +216,9 @@
VK_Mips_GOT_HI16,
VK_Mips_GOT_LO16,
VK_Mips_CALL_HI16,
- VK_Mips_CALL_LO16
+ VK_Mips_CALL_LO16,
+
+ VK_COFF_IMGREL32 // symbol@imgrel (image-relative)
};
private:
diff --git a/include/llvm/MC/MCWinCOFFObjectWriter.h b/include/llvm/MC/MCWinCOFFObjectWriter.h
index 11df574..f13e7d5 100644
--- a/include/llvm/MC/MCWinCOFFObjectWriter.h
+++ b/include/llvm/MC/MCWinCOFFObjectWriter.h
@@ -11,7 +11,9 @@
#define LLVM_MC_MCWINCOFFOBJECTWRITER_H
namespace llvm {
+ class MCFixup;
class MCObjectWriter;
+ class MCValue;
class raw_ostream;
class MCWinCOFFObjectTargetWriter {
@@ -24,7 +26,9 @@
virtual ~MCWinCOFFObjectTargetWriter() {}
unsigned getMachine() const { return Machine; }
- virtual unsigned getRelocType(unsigned FixupKind) const = 0;
+ virtual unsigned getRelocType(const MCValue &Target,
+ const MCFixup &Fixup,
+ bool IsCrossSection) const = 0;
};
/// \brief Construct a new Win COFF writer instance.
diff --git a/lib/MC/MCExpr.cpp b/lib/MC/MCExpr.cpp
index cd4d144..d54c264 100644
--- a/lib/MC/MCExpr.cpp
+++ b/lib/MC/MCExpr.cpp
@@ -250,6 +250,7 @@
case VK_Mips_GOT_LO16: return "GOT_LO16";
case VK_Mips_CALL_HI16: return "CALL_HI16";
case VK_Mips_CALL_LO16: return "CALL_LO16";
+ case VK_COFF_IMGREL32: return "IMGREL32";
}
llvm_unreachable("Invalid variant kind");
}
@@ -285,6 +286,8 @@
.Case("dtpoff", VK_DTPOFF)
.Case("TLVP", VK_TLVP)
.Case("tlvp", VK_TLVP)
+ .Case("IMGREL", VK_COFF_IMGREL32)
+ .Case("imgrel", VK_COFF_IMGREL32)
.Default(VK_Invalid);
}
diff --git a/lib/MC/WinCOFFObjectWriter.cpp b/lib/MC/WinCOFFObjectWriter.cpp
index 6dffed7..de7e67b 100644
--- a/lib/MC/WinCOFFObjectWriter.cpp
+++ b/lib/MC/WinCOFFObjectWriter.cpp
@@ -689,13 +689,8 @@
++Reloc.Symb->Relocations;
Reloc.Data.VirtualAddress += Fixup.getOffset();
-
- unsigned FixupKind = Fixup.getKind();
-
- if (CrossSection)
- FixupKind = FK_PCRel_4;
-
- Reloc.Data.Type = TargetObjectWriter->getRelocType(FixupKind);
+ Reloc.Data.Type = TargetObjectWriter->getRelocType(Target, Fixup,
+ CrossSection);
// FIXME: Can anyone explain what this does other than adjust for the size
// of the offset?
diff --git a/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp b/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
index bc272ef..ed64a32 100644
--- a/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
+++ b/lib/Target/X86/MCTargetDesc/X86WinCOFFObjectWriter.cpp
@@ -9,6 +9,8 @@
#include "MCTargetDesc/X86FixupKinds.h"
#include "MCTargetDesc/X86MCTargetDesc.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCValue.h"
#include "llvm/MC/MCWinCOFFObjectWriter.h"
#include "llvm/Support/COFF.h"
#include "llvm/Support/ErrorHandling.h"
@@ -27,7 +29,9 @@
X86WinCOFFObjectWriter(bool Is64Bit_);
~X86WinCOFFObjectWriter();
- virtual unsigned getRelocType(unsigned FixupKind) const;
+ virtual unsigned getRelocType(const MCValue &Target,
+ const MCFixup &Fixup,
+ bool IsCrossSection) const LLVM_OVERRIDE;
};
}
@@ -38,7 +42,14 @@
X86WinCOFFObjectWriter::~X86WinCOFFObjectWriter() {}
-unsigned X86WinCOFFObjectWriter::getRelocType(unsigned FixupKind) const {
+unsigned X86WinCOFFObjectWriter::getRelocType(const MCValue &Target,
+ const MCFixup &Fixup,
+ bool IsCrossSection) const {
+ unsigned FixupKind = IsCrossSection ? FK_PCRel_4 : Fixup.getKind();
+
+ MCSymbolRefExpr::VariantKind Modifier = Target.isAbsolute() ?
+ MCSymbolRefExpr::VK_None : Target.getSymA()->getKind();
+
switch (FixupKind) {
case FK_PCRel_4:
case X86::reloc_riprel_4byte:
@@ -46,6 +57,9 @@
return Is64Bit ? COFF::IMAGE_REL_AMD64_REL32 : COFF::IMAGE_REL_I386_REL32;
case FK_Data_4:
case X86::reloc_signed_4byte:
+ if (Modifier == MCSymbolRefExpr::VK_COFF_IMGREL32)
+ return Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32NB :
+ COFF::IMAGE_REL_I386_DIR32NB;
return Is64Bit ? COFF::IMAGE_REL_AMD64_ADDR32 : COFF::IMAGE_REL_I386_DIR32;
case FK_Data_8:
if (Is64Bit)
diff --git a/test/MC/COFF/relocation-imgrel.s b/test/MC/COFF/relocation-imgrel.s
new file mode 100644
index 0000000..ccd19ee
--- /dev/null
+++ b/test/MC/COFF/relocation-imgrel.s
@@ -0,0 +1,29 @@
+// COFF Image-relative relocations
+//
+// Test that we produce image-relative relocations (IMAGE_REL_I386_DIR32NB
+// and IMAGE_REL_AMD64_ADDR32NB) when accessing foo@imgrel.
+
+// RUN: llvm-mc -filetype=obj -triple i686-pc-win32 %s | llvm-readobj -r | FileCheck --check-prefix=W32 %s
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-win32 %s | llvm-readobj -r | FileCheck --check-prefix=W64 %s
+
+.data
+foo:
+ .long 1
+
+.text
+ mov foo@IMGREL(%ebx, %ecx, 4), %eax
+ mov foo@imgrel(%ebx, %ecx, 4), %eax
+
+// W32: Relocations [
+// W32-NEXT: Section (1) .text {
+// W32-NEXT: 0x3 IMAGE_REL_I386_DIR32NB foo
+// W32-NEXT: 0xA IMAGE_REL_I386_DIR32NB foo
+// W32-NEXT: }
+// W32-NEXT: ]
+
+// W64: Relocations [
+// W64-NEXT: Section (1) .text {
+// W64-NEXT: 0x4 IMAGE_REL_AMD64_ADDR32NB foo
+// W64-NEXT: 0xC IMAGE_REL_AMD64_ADDR32NB foo
+// W64-NEXT: }
+// W64-NEXT: ]