Even more explanation.

[oota-llvm.git] / lib / Target / PowerPC / PPCTargetMachine.cpp

diff --git a/lib/Target/PowerPC/PPCTargetMachine.cpp b/lib/Target/PowerPC/PPCTargetMachine.cpp
index 3d5ae5221af565f984afb66461ec1ff9d61c9770..c7f788238a345d845944876aac26f2217da79b79 100644 (file)
--- a/lib/Target/PowerPC/PPCTargetMachine.cpp
+++ b/lib/Target/PowerPC/PPCTargetMachine.cpp
@@ -12,36 +12,37 @@
 //===----------------------------------------------------------------------===//
 
 #include "PPC.h"
-#include "PPCTargetAsmInfo.h"
+#include "PPCMCAsmInfo.h"
 #include "PPCTargetMachine.h"
-#include "llvm/Module.h"
 #include "llvm/PassManager.h"
-#include "llvm/Target/TargetMachineRegistry.h"
 #include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetRegistry.h"
 #include "llvm/Support/FormattedStream.h"
 using namespace llvm;
 
-// Register the targets
-static RegisterTarget<PPC32TargetMachine>
-X(ThePPC32Target, "ppc32", "PowerPC 32");
-
-static RegisterTarget<PPC64TargetMachine>
-Y(ThePPC64Target, "ppc64", "PowerPC 64");
-
-// Force static initialization.
-extern "C" void LLVMInitializePowerPCTarget() { }
+static const MCAsmInfo *createMCAsmInfo(const Target &T, StringRef TT) {
+  Triple TheTriple(TT);
+  bool isPPC64 = TheTriple.getArch() == Triple::ppc64;
+  if (TheTriple.getOS() == Triple::Darwin)
+    return new PPCMCAsmInfoDarwin(isPPC64);
+  return new PPCLinuxMCAsmInfo(isPPC64);
+  
+}
 
-const TargetAsmInfo *PPCTargetMachine::createTargetAsmInfo() const {
-  if (Subtarget.isDarwin())
-    return new PPCDarwinTargetAsmInfo(*this);
-  else
-    return new PPCLinuxTargetAsmInfo(*this);
+extern "C" void LLVMInitializePowerPCTarget() {
+  // Register the targets
+  RegisterTargetMachine<PPC32TargetMachine> A(ThePPC32Target);  
+  RegisterTargetMachine<PPC64TargetMachine> B(ThePPC64Target);
+  
+  RegisterAsmInfoFn C(ThePPC32Target, createMCAsmInfo);
+  RegisterAsmInfoFn D(ThePPC64Target, createMCAsmInfo);
 }
 
-PPCTargetMachine::PPCTargetMachine(const Target&T, const Module &M, 
+
+PPCTargetMachine::PPCTargetMachine(const Target &T, const std::string &TT,
                                    const std::string &FS, bool is64Bit)
-  : LLVMTargetMachine(T),
-    Subtarget(*this, M, FS, is64Bit),
+  : LLVMTargetMachine(T, TT),
+    Subtarget(TT, FS, is64Bit),
     DataLayout(Subtarget.getTargetDataString()), InstrInfo(*this),
     FrameInfo(*this, is64Bit), JITInfo(*this, is64Bit), TLInfo(*this),
     InstrItins(Subtarget.getInstrItineraryData()), MachOWriterInfo(*this) {
@@ -58,15 +59,15 @@ PPCTargetMachine::PPCTargetMachine(const Target&T, const Module &M,
 /// groups, which typically degrades performance.
 bool PPCTargetMachine::getEnableTailMergeDefault() const { return false; }
 
-PPC32TargetMachine::PPC32TargetMachine(const Target &T, const Module &M, 
+PPC32TargetMachine::PPC32TargetMachine(const Target &T, const std::string &TT, 
                                        const std::string &FS) 
-  : PPCTargetMachine(T, M, FS, false) {
+  : PPCTargetMachine(T, TT, FS, false) {
 }
 
 
-PPC64TargetMachine::PPC64TargetMachine(const Target &T, const Module &M, 
+PPC64TargetMachine::PPC64TargetMachine(const Target &T, const std::string &TT, 
                                        const std::string &FS)
-  : PPCTargetMachine(T, M, FS, true) {
+  : PPCTargetMachine(T, TT, FS, true) {
 }
 
 
@@ -193,4 +194,31 @@ bool PPCTargetMachine::addSimpleCodeEmitter(PassManagerBase &PM,
   return false;
 }
 
-
+/// getLSDAEncoding - Returns the LSDA pointer encoding. The choices are 4-byte,
+/// 8-byte, and target default. The CIE is hard-coded to indicate that the LSDA
+/// pointer in the FDE section is an "sdata4", and should be encoded as a 4-byte
+/// pointer by default. However, some systems may require a different size due
+/// to bugs or other conditions. We will default to a 4-byte encoding unless the
+/// system tells us otherwise.
+///
+/// The issue is when the CIE says their is an LSDA. That mandates that every
+/// FDE have an LSDA slot. But if the function does not need an LSDA. There
+/// needs to be some way to signify there is none. The LSDA is encoded as
+/// pc-rel. But you don't look for some magic value after adding the pc. You
+/// have to look for a zero before adding the pc. The problem is that the size
+/// of the zero to look for depends on the encoding. The unwinder bug in SL is
+/// that it always checks for a pointer-size zero. So on x86_64 it looks for 8
+/// bytes of zero. If you have an LSDA, it works fine since the 8-bytes are
+/// non-zero so it goes ahead and then reads the value based on the encoding.
+/// But if you use sdata4 and there is no LSDA, then the test for zero gives a
+/// false negative and the unwinder thinks there is an LSDA.
+///
+/// FIXME: This call-back isn't good! We should be using the correct encoding
+/// regardless of the system. However, there are some systems which have bugs
+/// that prevent this from occuring.
+DwarfLSDAEncoding::Encoding PPCTargetMachine::getLSDAEncoding() const {
+  if (Subtarget.isDarwin() && Subtarget.getDarwinVers() != 10)
+    return DwarfLSDAEncoding::Default;
+
+  return DwarfLSDAEncoding::EightByte;
+}