[ARM] Add pre-defined macros for ROPI and RWPI

[olista01]

Summary

This adds pre-defined macros to test for code being compiled in the ROPI and RWPI position-independence modes. These macros will be defined in the next release of the ACLE.

[t.p.northover]

lib/Basic/Targets.cpp

5316 ↗

(On Diff #68347)

These names are pretty bad from a modern perspective (with APCS deprecated and almost entirely forgotten outside iOS). It's the kind of thing it would be good for the ACLE to cover, would they be likely to consider it?

[rengolin]

Was this abandoned?

[olista01]

I've proposed a patch to the ACLE to add these macros, but it's stalled in review. I've just given it a ping, I'll try to get an answer soon.

[olista01]

My patch to the ACLE has now been accepted, so it will be in the next release. This is the wording:

__ARM_ROPI is defined to 1 if the translation unit is being compiled in read-only position independent mode. In this mode, all read-only data and functions are at a link-time constant offset from the program counter.

__ARM_RWPI is defined to 1 if the translation unit is being compiled in read-write position independent mode. In this mode, all writable data is at a link-time constant offset from the static base register defined in [AAPCS].

The ROPI and RWPI position independence modes are compatible with each other, so the __ARM_ROPI and __ARM_RWPI macros may be defined at the same time.

We're not adding the FPIC macro to the ACLE, because that isn't ARM-specific.

[olista01]

Ping.

[kahmed]

Ping

[olista01]

These macros have been in the published ACLE for a while now: https://developer.arm.com/products/software-development-tools/compilers/arm-compiler-5/docs/101028/latest/5-feature-test-macros#position-independent-code

[rengolin]

Sorry for the delay, this fell out of my radar and just saw the ping now.

Given it's in ACLE and there are only mechanical (obvious) changes, LGTM.

I'm assuming those two parameters are already accepted in the LLVM back-end, right?

[olista01]

Yes, the back-end work was all done years ago, I just also forgot about these while waiting for the ACLE to be published.

cfe/trunk/include/clang/Basic/LangOptions.def

 COMPATIBLE_LANGOPT(Static            , 1, 0, "__STATIC__ predefined macro (as opposed to __DYNAMIC__)")
 VALUE_LANGOPT(PackStruct  , 32, 0,
               "default struct packing maximum alignment")
 VALUE_LANGOPT(MaxTypeAlign  , 32, 0,
               "default maximum alignment for types")
 VALUE_LANGOPT(AlignDouble            , 1, 0, "Controls if doubles should be aligned to 8 bytes (x86 only)")
 COMPATIBLE_VALUE_LANGOPT(PICLevel    , 2, 0, "__PIC__ level")
 COMPATIBLE_VALUE_LANGOPT(PIE         , 1, 0, "is pie")
+LANGOPT(ROPI                         , 1, 0, "Read-only position independence")
+LANGOPT(RWPI                         , 1, 0, "Read-write position independence")
 COMPATIBLE_LANGOPT(GNUInline         , 1, 0, "GNU inline semantics")
 COMPATIBLE_LANGOPT(NoInlineDefine    , 1, 0, "__NO_INLINE__ predefined macro")
 COMPATIBLE_LANGOPT(Deprecated        , 1, 0, "__DEPRECATED predefined macro")
 COMPATIBLE_LANGOPT(FastMath          , 1, 0, "fast FP math optimizations, and __FAST_MATH__ predefined macro")
 COMPATIBLE_LANGOPT(FiniteMathOnly    , 1, 0, "__FINITE_MATH_ONLY__ predefined macro")
 COMPATIBLE_LANGOPT(UnsafeFPMath      , 1, 0, "Unsafe Floating Point Math")
 
 BENIGN_LANGOPT(ObjCGCBitmapPrint , 1, 0, "printing of GC's bitmap layout for __weak/__strong ivars")

cfe/trunk/include/clang/Driver/Options.td

 def fpic : Flag<["-"], "fpic">, Group<f_Group>;
 def fno_pic : Flag<["-"], "fno-pic">, Group<f_Group>;
 def fpie : Flag<["-"], "fpie">, Group<f_Group>;
 def fno_pie : Flag<["-"], "fno-pie">, Group<f_Group>;
 def fplt : Flag<["-"], "fplt">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Use the PLT to make function calls">;
 def fno_plt : Flag<["-"], "fno-plt">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Do not use the PLT to make function calls">;
-def fropi : Flag<["-"], "fropi">, Group<f_Group>;
+def fropi : Flag<["-"], "fropi">, Group<f_Group>, Flags<[CC1Option]>;
 def fno_ropi : Flag<["-"], "fno-ropi">, Group<f_Group>;
-def frwpi : Flag<["-"], "frwpi">, Group<f_Group>;
+def frwpi : Flag<["-"], "frwpi">, Group<f_Group>, Flags<[CC1Option]>;
 def fno_rwpi : Flag<["-"], "fno-rwpi">, Group<f_Group>;
 def fplugin_EQ : Joined<["-"], "fplugin=">, Group<f_Group>, Flags<[DriverOption]>, MetaVarName<"<dsopath>">,
   HelpText<"Load the named plugin (dynamic shared object)">;
 def fpass_plugin_EQ : Joined<["-"], "fpass-plugin=">,
   Group<f_Group>, Flags<[CC1Option]>, MetaVarName<"<dsopath>">,
   HelpText<"Load pass plugin from a dynamic shared object file (only with new pass manager).">;
 def fpreserve_as_comments : Flag<["-"], "fpreserve-as-comments">, Group<f_Group>;
 def fno_preserve_as_comments : Flag<["-"], "fno-preserve-as-comments">, Group<f_Group>, Flags<[CC1Option]>,

cfe/trunk/lib/Basic/Targets/ARM.cpp

void ARMTargetInfo::getTargetDefines(const LangOptions &Opts,
   }
 
   if ((!SoftFloat && !SoftFloatABI) || ABI == "aapcs-vfp" || ABI == "aapcs16")
     Builder.defineMacro("__ARM_PCS_VFP", "1");
 
   if (SoftFloat)
     Builder.defineMacro("__SOFTFP__");
 
+  // ACLE position independent code macros.
+  if (Opts.ROPI)
+    Builder.defineMacro("__ARM_ROPI", "1");
+  if (Opts.RWPI)
+    Builder.defineMacro("__ARM_RWPI", "1");
+
   if (ArchKind == llvm::ARM::ArchKind::XSCALE)
     Builder.defineMacro("__XSCALE__");
 
   if (isThumb()) {
     Builder.defineMacro("__THUMBEL__");
     Builder.defineMacro("__thumb__");
     if (supportsThumb2())
       Builder.defineMacro("__thumb2__");

cfe/trunk/lib/Driver/ToolChains/Clang.cpp

#endif
   }
   if (PICLevel > 0) {
     CmdArgs.push_back("-pic-level");
     CmdArgs.push_back(PICLevel == 1 ? "1" : "2");
     if (IsPIE)
       CmdArgs.push_back("-pic-is-pie");
   }
 
+  if (RelocationModel == llvm::Reloc::ROPI ||
+      RelocationModel == llvm::Reloc::ROPI_RWPI)
+    CmdArgs.push_back("-fropi");
+  if (RelocationModel == llvm::Reloc::RWPI ||
+      RelocationModel == llvm::Reloc::ROPI_RWPI)
+    CmdArgs.push_back("-frwpi");
+
   if (Arg *A = Args.getLastArg(options::OPT_meabi)) {
     CmdArgs.push_back("-meabi");
     CmdArgs.push_back(A->getValue());
   }
 
   CmdArgs.push_back("-mthread-model");
   if (Arg *A = Args.getLastArg(options::OPT_mthread_model)) {
     if (!TC.isThreadModelSupported(A->getValue()))

cfe/trunk/lib/Frontend/CompilerInvocation.cpp

Opts.ObjCDefaultSynthProperties =
     !Args.hasArg(OPT_disable_objc_default_synthesize_properties);
   Opts.EncodeExtendedBlockSig =
     Args.hasArg(OPT_fencode_extended_block_signature);
   Opts.EmitAllDecls = Args.hasArg(OPT_femit_all_decls);
   Opts.PackStruct = getLastArgIntValue(Args, OPT_fpack_struct_EQ, 0, Diags);
   Opts.MaxTypeAlign = getLastArgIntValue(Args, OPT_fmax_type_align_EQ, 0, Diags);
   Opts.AlignDouble = Args.hasArg(OPT_malign_double);
   Opts.PICLevel = getLastArgIntValue(Args, OPT_pic_level, 0, Diags);
+  Opts.ROPI = Args.hasArg(OPT_fropi);
+  Opts.RWPI = Args.hasArg(OPT_frwpi);
   Opts.PIE = Args.hasArg(OPT_pic_is_pie);
   Opts.Static = Args.hasArg(OPT_static_define);
   Opts.DumpRecordLayoutsSimple = Args.hasArg(OPT_fdump_record_layouts_simple);
   Opts.DumpRecordLayouts = Opts.DumpRecordLayoutsSimple
                         || Args.hasArg(OPT_fdump_record_layouts);
   Opts.DumpVTableLayouts = Args.hasArg(OPT_fdump_vtable_layouts);
   Opts.SpellChecking = !Args.hasArg(OPT_fno_spell_checking);
   Opts.NoBitFieldTypeAlign = Args.hasArg(OPT_fno_bitfield_type_align);

cfe/trunk/test/Preprocessor/arm-pic-predefines.c

+// REQUIRES: arm-registered-target
+
+// RUN: %clang -target armv8--none-eabi   -x c -E -dM %s -o -               | FileCheck %s --check-prefix=NO-ROPI --check-prefix=NO-RWPI
+// RUN: %clang -target armv8--none-eabi   -x c -E -dM %s -o - -fropi        | FileCheck %s --check-prefix=ROPI    --check-prefix=NO-RWPI
+// RUN: %clang -target armv8--none-eabi   -x c -E -dM %s -o - -frwpi        | FileCheck %s --check-prefix=NO-ROPI --check-prefix=RWPI
+// RUN: %clang -target armv8--none-eabi   -x c -E -dM %s -o - -fropi -frwpi | FileCheck %s --check-prefix=ROPI    --check-prefix=RWPI
+
+// Pre-defined macros for position-independence modes
+
+// NO-ROPI-NOT: #define __APCS_ROPI
+// ROPI: #define __ARM_ROPI
+
+// NO-RWPI-NOT: #define __APCS_RWPI
+// RWPI: #define __ARM_RWPI