Sketch out PowerPC ELF writer. This is enough to get clang -integrated-as
to compile a working hello world on FreeBSD/PPC32.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@136689 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp b/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
index 290e61a..95f929a 100644
--- a/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
+++ b/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
@@ -10,14 +10,40 @@
#include "llvm/MC/MCAsmBackend.h"
#include "MCTargetDesc/PPCMCTargetDesc.h"
#include "MCTargetDesc/PPCFixupKinds.h"
+#include "llvm/MC/MCELFObjectWriter.h"
#include "llvm/MC/MCMachObjectWriter.h"
#include "llvm/MC/MCSectionMachO.h"
#include "llvm/MC/MCObjectWriter.h"
#include "llvm/MC/MCValue.h"
#include "llvm/Object/MachOFormat.h"
+#include "llvm/Support/ELF.h"
+#include "llvm/Support/ErrorHandling.h"
#include "llvm/Target/TargetRegistry.h"
using namespace llvm;
+static unsigned adjustFixupValue(unsigned Kind, uint64_t Value) {
+ switch (Kind) {
+ default:
+ llvm_unreachable("Unknown fixup kind!");
+ case FK_Data_1:
+ case FK_Data_2:
+ case FK_Data_4:
+ return Value;
+ case PPC::fixup_ppc_brcond14:
+ return Value & 0x3ffc;
+ case PPC::fixup_ppc_br24:
+ return Value & 0x3fffffc;
+#if 0
+ case PPC::fixup_ppc_hi16:
+ return (Value >> 16) & 0xffff;
+#endif
+ case PPC::fixup_ppc_ha16:
+ return ((Value >> 16) + ((Value & 0x8000) ? 1 : 0)) & 0xffff;
+ case PPC::fixup_ppc_lo16:
+ return Value & 0xffff;
+ }
+}
+
namespace {
class PPCMachObjectWriter : public MCMachObjectTargetWriter {
public:
@@ -31,6 +57,13 @@
MCValue Target, uint64_t &FixedValue) {}
};
+class PPCELFObjectWriter : public MCELFObjectTargetWriter {
+public:
+ PPCELFObjectWriter(bool Is64Bit, Triple::OSType OSType, uint16_t EMachine,
+ bool HasRelocationAddend, bool isLittleEndian)
+ : MCELFObjectTargetWriter(Is64Bit, OSType, EMachine, HasRelocationAddend) {}
+};
+
class PPCAsmBackend : public MCAsmBackend {
const Target &TheTarget;
public:
@@ -109,6 +142,42 @@
return false;
}
};
+
+ class ELFPPCAsmBackend : public PPCAsmBackend {
+ Triple::OSType OSType;
+ public:
+ ELFPPCAsmBackend(const Target &T, Triple::OSType OSType) :
+ PPCAsmBackend(T), OSType(OSType) { }
+
+ void ApplyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
+ uint64_t Value) const {
+ Value = adjustFixupValue(Fixup.getKind(), Value);
+ if (!Value) return; // Doesn't change encoding.
+
+ unsigned Offset = Fixup.getOffset();
+
+ // For each byte of the fragment that the fixup touches, mask in the bits from
+ // the fixup value. The Value has been "split up" into the appropriate
+ // bitfields above.
+ for (unsigned i = 0; i != 4; ++i)
+ Data[Offset + i] |= uint8_t((Value >> ((4 - i - 1)*8)) & 0xff);
+ }
+
+ MCObjectWriter *createObjectWriter(raw_ostream &OS) const {
+ bool is64 = getPointerSize() == 8;
+ return createELFObjectWriter(new PPCELFObjectWriter(
+ /*Is64Bit=*/is64,
+ OSType,
+ is64 ? ELF::EM_PPC64 : ELF::EM_PPC,
+ /*addend*/ true, /*isLittleEndian*/ false),
+ OS, /*IsLittleEndian=*/false);
+ }
+
+ virtual bool doesSectionRequireSymbols(const MCSection &Section) const {
+ return false;
+ }
+ };
+
} // end anonymous namespace
@@ -118,5 +187,5 @@
if (Triple(TT).isOSDarwin())
return new DarwinPPCAsmBackend(T);
- return 0;
+ return new ELFPPCAsmBackend(T, Triple(TT).getOS());
}