[PATCH] D56878: [mips] Add '-mrelax-pic-calls', '-mno-relax-pic-calls'

[Vladimir Stefanovic via Phabricator via cfe-commits]

vstefanovic created this revision.
vstefanovic added a reviewer: atanasyan.
Herald added subscribers: jrtc27, arichardson, sdardis.

These two options enable/disable emission of R_{MICRO}MIPS_JALR fixups along
with PIC calls. The linker may then try to turn PIC calls into direct jumps.
By default, these fixups do get emitted by the backend, use
'-mno-relax-pic-calls' to omit them.


Repository:
  rC Clang

https://reviews.llvm.org/D56878

Files:
  include/clang/Driver/Options.td
  lib/Driver/ToolChains/Clang.cpp
  test/Driver/mips-features.c


Index: test/Driver/mips-features.c
===================================================================
--- test/Driver/mips-features.c
+++ test/Driver/mips-features.c
@@ -444,3 +444,15 @@
 // RUN:     -mginv -mno-ginv 2>&1 \
 // RUN:   | FileCheck --check-prefix=CHECK-NO-GINV %s
 // CHECK-NO-GINV: "-target-feature" "-ginv"
+//
+// -mrelax-pic-calls
+// RUN: %clang -target mips-unknown-linux-gnu -### -c %s \
+// RUN:     -mno-relax-pic-calls -mrelax-pic-calls 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-RELAX-PIC-CALLS %s
+// CHECK-RELAX-PIC-CALLS-NOT: "-mllvm" "-mips-jalr-reloc=0"
+//
+// -mno-relax-pic-calls
+// RUN: %clang -target mips-unknown-linux-gnu -### -c %s \
+// RUN:     -mrelax-pic-calls -mno-relax-pic-calls 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-NO-RELAX-PIC-CALLS %s
+// CHECK-NO-RELAX-PIC-CALLS: "-mllvm" "-mips-jalr-reloc=0"
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -1712,6 +1712,14 @@
     } else
       D.Diag(diag::warn_target_unsupported_compact_branches) << CPUName;
   }
+
+  if (Arg *A = Args.getLastArg(options::OPT_mrelax_pic_calls,
+                               options::OPT_mno_relax_pic_calls)) {
+    if (A->getOption().matches(options::OPT_mno_relax_pic_calls)) {
+      CmdArgs.push_back("-mllvm");
+      CmdArgs.push_back(Args.MakeArgString("-mips-jalr-reloc=0"));
+    }
+  }
 }
 
 void Clang::AddPPCTargetArgs(const ArgList &Args,
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -2402,6 +2402,14 @@
 def mno_odd_spreg : Flag<["-"], "mno-odd-spreg">, Group<m_mips_Features_Group>,
   HelpText<"Disable odd single-precision floating point registers">,
   Flags<[HelpHidden]>;
+def mrelax_pic_calls : Flag<["-"], "mrelax-pic-calls">,
+  Group<m_mips_Features_Group>,
+  HelpText<"Try turning PIC calls (j{al}r{c} $25) into direct calls "
+  "(MIPS only)">, Flags<[HelpHidden]>;
+def mno_relax_pic_calls : Flag<["-"], "mno-relax-pic-calls">,
+  Group<m_mips_Features_Group>,
+  HelpText<"Do not try turning PIC calls (j{al}r{c} $25) into direct calls "
+  "(MIPS only)">, Flags<[HelpHidden]>;
 def mglibc : Flag<["-"], "mglibc">, Group<m_libc_Group>, Flags<[HelpHidden]>;
 def muclibc : Flag<["-"], "muclibc">, Group<m_libc_Group>, Flags<[HelpHidden]>;
 def module_file_info : Flag<["-"], "module-file-info">, Flags<[DriverOption,CC1Option]>, Group<Action_Group>,


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