Delete Reloc::Default.

Having an enum member named Default is quite confusing: Is it distinct
from the others?

This patch removes that member and instead uses Optional<Reloc> in
places where we have a user input that still hasn't been maped to the
default value, which is now clear has no be one of the remaining 3
options.

llvm-svn: 269988

1 files changed, 40 insertions, 4 deletions

diff --git a/llvm/lib/Target/X86/X86TargetMachine.cpp b/llvm/lib/Target/X86/X86TargetMachine.cpp
index 1fe98a6..3ff847a 100644
--- a/llvm/lib/Target/X86/X86TargetMachine.cpp
+++ b/llvm/lib/Target/X86/X86TargetMachine.cpp
@@ -106,15 +106,51 @@ static std::string computeDataLayout(const Triple &TT) {
   return Ret;
 }
 
+static Reloc::Model getEffectiveRelocModel(const Triple &TT,
+                                           Optional<Reloc::Model> RM) {
+  bool is64Bit = TT.getArch() == Triple::x86_64;
+  if (!RM.hasValue()) {
+    // Darwin defaults to PIC in 64 bit mode and dynamic-no-pic in 32 bit mode.
+    // Win64 requires rip-rel addressing, thus we force it to PIC. Otherwise we
+    // use static relocation model by default.
+    if (TT.isOSDarwin()) {
+      if (is64Bit)
+        return Reloc::PIC_;
+      return Reloc::DynamicNoPIC;
+    }
+    if (TT.isOSWindows() && is64Bit)
+      return Reloc::PIC_;
+    return Reloc::Static;
+  }
+
+  // ELF and X86-64 don't have a distinct DynamicNoPIC model.  DynamicNoPIC
+  // is defined as a model for code which may be used in static or dynamic
+  // executables but not necessarily a shared library. On X86-32 we just
+  // compile in -static mode, in x86-64 we use PIC.
+  if (*RM == Reloc::DynamicNoPIC) {
+    if (is64Bit)
+      return Reloc::PIC_;
+    if (!TT.isOSDarwin())
+      return Reloc::Static;
+  }
+
+  // If we are on Darwin, disallow static relocation model in X86-64 mode, since
+  // the Mach-O file format doesn't support it.
+  if (*RM == Reloc::Static && TT.isOSDarwin() && is64Bit)
+    return Reloc::PIC_;
+
+  return *RM;
+}
+
 /// Create an X86 target.
 ///
 X86TargetMachine::X86TargetMachine(const Target &T, const Triple &TT,
                                    StringRef CPU, StringRef FS,
                                    const TargetOptions &Options,
-                                   Reloc::Model RM, CodeModel::Model CM,
-                                   CodeGenOpt::Level OL)
-    : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options, RM, CM,
-                        OL),
+                                   Optional<Reloc::Model> RM,
+                                   CodeModel::Model CM, CodeGenOpt::Level OL)
+    : LLVMTargetMachine(T, computeDataLayout(TT), TT, CPU, FS, Options,
+                        getEffectiveRelocModel(TT, RM), CM, OL),
       TLOF(createTLOF(getTargetTriple())),
       Subtarget(TT, CPU, FS, *this, Options.StackAlignmentOverride) {
   // Windows stack unwinder gets confused when execution flow "falls through"