[X86] Implement disabling APX relocations and EPGR/NDD instrs for them

Introduce an option (-mapx-relax-relocations) to control the emission of the
new APX relocations. It's off by default to keep backward compatibility with
older version of ld and other linkers without APX support. And EGPR and NDD are
also suppressed to avoid the instructions updated incorrectly by older version
of linker.

Author: fzou1

clang/CMakeLists.txt

@@ -219,6 +219,9 @@ set(ENABLE_LINKER_BUILD_ID OFF CACHE BOOL "pass --build-id to ld")
 set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL
     "enable x86 relax relocations by default")
 
+set(ENABLE_X86_APX_RELAX_RELOCATIONS OFF CACHE BOOL
+    "Enable x86 APX relax relocations by default")
+
 set(PPC_LINUX_DEFAULT_IEEELONGDOUBLE OFF CACHE BOOL
     "Enable IEEE binary128 as default long double format on PowerPC Linux.")
 

clang/cmake/caches/Fuchsia-stage2.cmake

@@ -49,6 +49,7 @@ set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
 
 set(ENABLE_LINKER_BUILD_ID ON CACHE BOOL "")
 set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL "")
+set(ENABLE_X86_APX_RELAX_RELOCATIONS OFF CACHE BOOL "")
 
 # TODO(#67176): relative-vtables doesn't play well with different default
 # visibilities. Making everything hidden visibility causes other complications

clang/cmake/caches/Fuchsia.cmake

@@ -89,6 +89,7 @@ set(CLANG_PLUGIN_SUPPORT OFF CACHE BOOL "")
 
 set(ENABLE_LINKER_BUILD_ID ON CACHE BOOL "")
 set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL "")
+set(ENABLE_X86_APX_RELAX_RELOCATIONS OFF CACHE BOOL "")
 
 set(LLVM_ENABLE_ASSERTIONS ON CACHE BOOL "")
 set(LLVM_ENABLE_BACKTRACES ON CACHE BOOL "")

clang/include/clang/Basic/CodeGenOptions.def

@@ -201,6 +201,7 @@ CODEGENOPT(UniqueInternalLinkageNames, 1, 0) ///< Internal Linkage symbols get u
 CODEGENOPT(SplitMachineFunctions, 1, 0) ///< Split machine functions using profile information.
 CODEGENOPT(PPCUseFullRegisterNames, 1, 0) ///< Print full register names in assembly
 CODEGENOPT(X86RelaxRelocations, 1, 1) ///< -Wa,-mrelax-relocations={yes,no}
+CODEGENOPT(X86APXRelaxRelocations, 1, 0) ///< -Wa,-mrelax-relocations={yes,no}
 CODEGENOPT(X86Sse2Avx        , 1, 0)   ///< -Wa,-msse2avx
 
 /// When false, this attempts to generate code as if the result of an

clang/include/clang/Config/config.h.cmake

@@ -72,6 +72,9 @@
 /* enable x86 relax relocations by default */
 #cmakedefine01 ENABLE_X86_RELAX_RELOCATIONS
 
+/* enable x86 APX relax relocations by default */
+#cmakedefine01 ENABLE_X86_APX_RELAX_RELOCATIONS
+
 /* Enable IEEE binary128 as default long double format on PowerPC Linux. */
 #cmakedefine01 PPC_LINUX_DEFAULT_IEEELONGDOUBLE
 

clang/include/clang/Driver/Options.td

@@ -7442,6 +7442,9 @@ def mmapsyms_implicit : Flag<["-"], "mmapsyms=implicit">,
 def mrelax_relocations_no : Flag<["-"], "mrelax-relocations=no">,
     HelpText<"Disable x86 relax relocations">,
     MarshallingInfoNegativeFlag<CodeGenOpts<"X86RelaxRelocations">>;
+def mapx_relax_relocations_yes : Flag<["-"], "mapx-relax-relocations=yes">,
+    HelpText<"Enable x86 APX relax relocations">,
+    MarshallingInfoNegativeFlag<CodeGenOpts<"X86APXRelaxRelocations">>;
 def msave_temp_labels : Flag<["-"], "msave-temp-labels">,
   HelpText<"Save temporary labels in the symbol table. "
            "Note this may change .s semantics and shouldn't generally be used "

clang/include/clang/Driver/ToolChain.h

@@ -473,6 +473,9 @@ class ToolChain {
   /// Check whether to enable x86 relax relocations by default.
   virtual bool useRelaxRelocations() const;
 
+  /// Check whether to enable x86 APX relax relocations by default.
+  virtual bool useAPXRelaxRelocations() const;
+
   /// Check whether use IEEE binary128 as long double format by default.
   bool defaultToIEEELongDouble() const;
 

clang/lib/CodeGen/BackendUtil.cpp

@@ -513,6 +513,7 @@ static bool initTargetOptions(const CompilerInstance &CI,
   Options.MCOptions.Crel = CodeGenOpts.Crel;
   Options.MCOptions.ImplicitMapSyms = CodeGenOpts.ImplicitMapSyms;
   Options.MCOptions.X86RelaxRelocations = CodeGenOpts.X86RelaxRelocations;
+  Options.MCOptions.X86APXRelaxRelocations = CodeGenOpts.X86APXRelaxRelocations;
   Options.MCOptions.CompressDebugSections =
       CodeGenOpts.getCompressDebugSections();
   if (CodeGenOpts.OutputAsmVariant != 3) // 3 (default): not specified

clang/lib/Driver/ToolChain.cpp

@@ -192,6 +192,10 @@ bool ToolChain::useRelaxRelocations() const {
   return ENABLE_X86_RELAX_RELOCATIONS;
 }
 
+bool ToolChain::useAPXRelaxRelocations() const {
+  return ENABLE_X86_APX_RELAX_RELOCATIONS;
+}
+
 bool ToolChain::defaultToIEEELongDouble() const {
   return PPC_LINUX_DEFAULT_IEEELONGDOUBLE && getTriple().isOSLinux();
 }

clang/lib/Driver/ToolChains/Clang.cpp

@@ -2602,6 +2602,8 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
   bool Crel = false, ExperimentalCrel = false;
   bool ImplicitMapSyms = false;
   bool UseRelaxRelocations = C.getDefaultToolChain().useRelaxRelocations();
+  bool UseAPXRelaxRelocations =
+      C.getDefaultToolChain().useAPXRelaxRelocations();
   bool UseNoExecStack = false;
   bool Msa = false;
   const char *MipsTargetFeature = nullptr;
@@ -2663,6 +2665,12 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
           checkArg(IsELF, {"yes", "no"});
           continue;
         }
+        if (Equal.first == "-mapx-relax-relocations" ||
+            Equal.first == "--mapx-relax-relocations") {
+          UseAPXRelaxRelocations = Equal.second == "yes";
+          checkArg(IsELF, {"yes", "no"});
+          continue;
+        }
         if (Value == "-msse2avx") {
           CmdArgs.push_back("-msse2avx");
           continue;
@@ -2874,6 +2882,8 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
     CmdArgs.push_back("-mmsa");
   if (!UseRelaxRelocations)
     CmdArgs.push_back("-mrelax-relocations=no");
+  if (UseAPXRelaxRelocations)
+    CmdArgs.push_back("-mapx-relax-relocations=yes");
   if (UseNoExecStack)
     CmdArgs.push_back("-mnoexecstack");
   if (MipsTargetFeature != nullptr) {