Delete Default and JITDefault code models
IMHO it is an antipattern to have a enum value that is Default.
At any given piece of code it is not clear if we have to handle
Default or if has already been mapped to a concrete value. In this
case in particular, only the target can do the mapping and it is nice
to make sure it is always done.
This deletes the two default enum values of CodeModel and uses an
explicit Optional<CodeModel> when it is possible that it is
unspecified.
llvm-svn: 309911
diff --git a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp b/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
index 025bf73..aa76a96 100644
--- a/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
+++ b/llvm/lib/Target/SystemZ/SystemZTargetMachine.cpp
@@ -99,14 +99,54 @@
return *RM;
}
+// For SystemZ we define the models as follows:
+//
+// Small: BRASL can call any function and will use a stub if necessary.
+// Locally-binding symbols will always be in range of LARL.
+//
+// Medium: BRASL can call any function and will use a stub if necessary.
+// GOT slots and locally-defined text will always be in range
+// of LARL, but other symbols might not be.
+//
+// Large: Equivalent to Medium for now.
+//
+// Kernel: Equivalent to Medium for now.
+//
+// This means that any PIC module smaller than 4GB meets the
+// requirements of Small, so Small seems like the best default there.
+//
+// All symbols bind locally in a non-PIC module, so the choice is less
+// obvious. There are two cases:
+//
+// - When creating an executable, PLTs and copy relocations allow
+// us to treat external symbols as part of the executable.
+// Any executable smaller than 4GB meets the requirements of Small,
+// so that seems like the best default.
+//
+// - When creating JIT code, stubs will be in range of BRASL if the
+// image is less than 4GB in size. GOT entries will likewise be
+// in range of LARL. However, the JIT environment has no equivalent
+// of copy relocs, so locally-binding data symbols might not be in
+// the range of LARL. We need the Medium model in that case.
+static CodeModel::Model getEffectiveCodeModel(Optional<CodeModel::Model> CM,
+ Reloc::Model RM, bool JIT) {
+ if (CM)
+ return *CM;
+ if (JIT)
+ return RM == Reloc::PIC_ ? CodeModel::Small : CodeModel::Medium;
+ return CodeModel::Small;
+}
+
SystemZTargetMachine::SystemZTargetMachine(const Target &T, const Triple &TT,
StringRef CPU, StringRef FS,
const TargetOptions &Options,
Optional<Reloc::Model> RM,
- CodeModel::Model CM,
- CodeGenOpt::Level OL)
- : LLVMTargetMachine(T, computeDataLayout(TT, CPU, FS), TT, CPU, FS, Options,
- getEffectiveRelocModel(RM), CM, OL),
+ Optional<CodeModel::Model> CM,
+ CodeGenOpt::Level OL, bool JIT)
+ : LLVMTargetMachine(
+ T, computeDataLayout(TT, CPU, FS), TT, CPU, FS, Options,
+ getEffectiveRelocModel(RM),
+ getEffectiveCodeModel(CM, getEffectiveRelocModel(RM), JIT), OL),
TLOF(llvm::make_unique<TargetLoweringObjectFileELF>()),
Subtarget(TT, CPU, FS, *this) {
initAsmInfo();