[Driver] Make the use of relax relocations a per target option

The support for relax relocations is dependent on the linker and
different toolchains within the same compiler can be using different
linkers some of which may or may not support relax relocations.

Give toolchains the option to control whether they want to use relax
relocations in addition to the existing (global) build system option.

Differential Revision: https://reviews.llvm.org/D39831

llvm-svn: 318816

diff --git a/clang/cmake/caches/Fuchsia-stage2.cmake b/clang/cmake/caches/Fuchsia-stage2.cmake
index d2f19fd..b5841e2 100644 (file)
--- a/clang/cmake/caches/Fuchsia-stage2.cmake
+++ b/clang/cmake/caches/Fuchsia-stage2.cmake
@@ -18,13 +18,6 @@ if(NOT APPLE)
   set(CLANG_DEFAULT_LINKER lld CACHE STRING "")
 endif()
 
-# This is a "Does your linker support it?" option that only applies
-# to x86-64 ELF targets.  All Fuchsia target linkers do support it.
-# For x86-64 Linux, it's supported by LLD and by GNU linkers since
-# binutils 2.27, so one can hope that all Linux hosts in use handle it.
-# Ideally this would be settable as a per-target option.
-set(ENABLE_X86_RELAX_RELOCATIONS ON CACHE BOOL "")
-
 if(APPLE)
   set(LLDB_CODESIGN_IDENTITY "" CACHE STRING "")
 endif()

diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
index 1206794..bd71038 100644 (file)
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -316,6 +316,9 @@ public:
   /// mixed dispatch method be used?
   virtual bool UseObjCMixedDispatch() const { return false; }
 
+  /// \brief Check whether to enable x86 relax relocations by default.
+  virtual bool useRelaxRelocations() const;
+
   /// GetDefaultStackProtectorLevel - Get the default stack protector level for
   /// this tool chain (0=off, 1=on, 2=strong, 3=all).
   virtual unsigned GetDefaultStackProtectorLevel(bool KernelOrKext) const {

diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index fac0a5b..741f428 100644 (file)
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -90,6 +90,10 @@ bool ToolChain::useIntegratedAs() const {
                       IsIntegratedAssemblerDefault());
 }
 
+bool ToolChain::useRelaxRelocations() const {
+  return ENABLE_X86_RELAX_RELOCATIONS;
+}
+
 const SanitizerArgs& ToolChain::getSanitizerArgs() const {
   if (!SanitizerArguments.get())
     SanitizerArguments.reset(new SanitizerArgs(*this, Args));

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 3ab28d4..d96664c 100644 (file)
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1869,7 +1869,7 @@ static void CollectArgsForIntegratedAssembler(Compilation &C,
   // arg after parsing the '-I' arg.
   bool TakeNextArg = false;
 
-  bool UseRelaxRelocations = ENABLE_X86_RELAX_RELOCATIONS;
+  bool UseRelaxRelocations = C.getDefaultToolChain().useRelaxRelocations();
   const char *MipsTargetFeature = nullptr;
   for (const Arg *A :
        Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler)) {

diff --git a/clang/lib/Driver/ToolChains/Fuchsia.h b/clang/lib/Driver/ToolChains/Fuchsia.h
index 6d825fb..6f438de 100644 (file)
--- a/clang/lib/Driver/ToolChains/Fuchsia.h
+++ b/clang/lib/Driver/ToolChains/Fuchsia.h
@@ -43,6 +43,7 @@ public:
   bool HasNativeLLVMSupport() const override { return true; }
   bool IsIntegratedAssemblerDefault() const override { return true; }
   bool IsMathErrnoDefault() const override { return false; }
+  bool useRelaxRelocations() const override { return true; };
   RuntimeLibType GetDefaultRuntimeLibType() const override {
     return ToolChain::RLT_CompilerRT;
   }

diff --git a/clang/test/Driver/fuchsia.c b/clang/test/Driver/fuchsia.c
index 3f5597c..eb413b7 100644 (file)
--- a/clang/test/Driver/fuchsia.c
+++ b/clang/test/Driver/fuchsia.c
@@ -5,6 +5,7 @@
 // RUN:     --sysroot=%S/platform 2>&1 \
 // RUN:     | FileCheck -check-prefixes=CHECK,CHECK-AARCH64 %s
 // CHECK: {{.*}}clang{{.*}}" "-cc1"
+// CHECK: "--mrelax-relocations"
 // CHECK: "-munwind-tables"
 // CHECK: "-fuse-init-array"
 // CHECK: "-isysroot" "[[SYSROOT:[^"]+]]"