Reland "[mips] Teach the driver to accept -m(no-)gpopt."

This patch teaches the driver to pass -mgpopt by default to the backend when it
is supported, i.e. we are using -mno-abicalls.

Reviewers: atanasyan, slthakur

Differential Revision: https://reviews.llvm.org/D35548

This version fixes a logic error that generated warnings incorrectly and
gets rid of spurious arguments to the backend when -mgpopt is not used.

llvm-svn: 308619

clang/include/clang/Basic/DiagnosticDriverKinds.td

@@ -279,6 +279,10 @@ def warn_target_unsupported_nanlegacy : Warning<
 def warn_target_unsupported_compact_branches : Warning<
   "ignoring '-mcompact-branches=' option because the '%0' architecture does not"
   " support it">, InGroup<UnsupportedCB>;
+def warn_drv_unsupported_gpopt : Warning<
+  "ignoring '-mgpopt' option as it cannot be used with %select{|the implicit"
+  " usage of}0-mabicalls">,
+  InGroup<UnsupportedGPOpt>;
 
 def warn_drv_unable_to_find_directory_expected : Warning<
   "unable to find %0 directory, expected to be in '%1'">,

clang/include/clang/Basic/DiagnosticGroups.td

@@ -61,6 +61,7 @@ def DoublePromotion : DiagGroup<"double-promotion">;
 def EnumTooLarge : DiagGroup<"enum-too-large">;
 def UnsupportedNan : DiagGroup<"unsupported-nan">;
 def UnsupportedCB : DiagGroup<"unsupported-cb">;
+def UnsupportedGPOpt : DiagGroup<"unsupported-gpopt">;
 def NonLiteralNullConversion : DiagGroup<"non-literal-null-conversion">;
 def NullConversion : DiagGroup<"null-conversion">;
 def ImplicitConversionFloatingPointToBool :

clang/include/clang/Driver/Options.td

@@ -2035,6 +2035,12 @@ def mfp64 : Flag<["-"], "mfp64">, Group<m_Group>,
   HelpText<"Use 64-bit floating point registers (MIPS only)">;
 def mfp32 : Flag<["-"], "mfp32">, Group<m_Group>,
   HelpText<"Use 32-bit floating point registers (MIPS only)">;
+def mgpopt : Flag<["-"], "mgpopt">, Group<m_Group>,
+  HelpText<"Use GP relative accesses for symbols known to be in a small"
+           " data section (MIPS)">;
+def mno_gpopt : Flag<["-"], "mno-gpopt">, Group<m_Group>,
+  HelpText<"Do not use GP relative accesses for symbols known to be in a small"
+           " data section (MIPS)">;
 def mnan_EQ : Joined<["-"], "mnan=">, Group<m_Group>;
 def mabicalls : Flag<["-"], "mabicalls">, Group<m_Group>,
   HelpText<"Enable SVR4-style position-independent code (Mips only)">;

clang/lib/Driver/ToolChains/Clang.cpp

@@ -1462,6 +1462,30 @@ void Clang::AddMIPSTargetArgs(const ArgList &Args,
     A->claim();
   }
 
+  Arg *GPOpt = Args.getLastArg(options::OPT_mgpopt, options::OPT_mno_gpopt);
+  Arg *ABICalls =
+      Args.getLastArg(options::OPT_mabicalls, options::OPT_mno_abicalls);
+
+  // -mabicalls is the default for many MIPS environments, even with -fno-pic.
+  // -mgpopt is the default for static, -fno-pic environments but these two
+  // options conflict. We want to be certain that -mno-abicalls -mgpopt is
+  // the only case where -mllvm -mgpopt is passed.
+  // NOTE: We need a warning here or in the backend to warn when -mgpopt is
+  //       passed explicitly when compiling something with -mabicalls
+  //       (implictly) in affect. Currently the warning is in the backend.
+  bool NoABICalls =
+      ABICalls && ABICalls->getOption().matches(options::OPT_mno_abicalls);
+  bool WantGPOpt = GPOpt && GPOpt->getOption().matches(options::OPT_mgpopt);
+  // We quietly ignore -mno-gpopt as the backend defaults to -mno-gpopt.
+  if (NoABICalls && (!GPOpt || WantGPOpt)) {
+    CmdArgs.push_back("-mllvm");
+    CmdArgs.push_back("-mgpopt");
+  } else if ((!ABICalls || (!NoABICalls && ABICalls)) && WantGPOpt)
+    D.Diag(diag::warn_drv_unsupported_gpopt) << (ABICalls ? 0 : 1);
+
+  if (GPOpt)
+    GPOpt->claim();
+
   if (Arg *A = Args.getLastArg(options::OPT_mcompact_branches_EQ)) {
     StringRef Val = StringRef(A->getValue());
     if (mips::hasCompactBranches(CPUName)) {

clang/test/Driver/mips-features.c

@@ -10,6 +10,31 @@
 // RUN:   | FileCheck --check-prefix=CHECK-MNOABICALLS %s
 // CHECK-MNOABICALLS: "-target-feature" "+noabicalls"
 //
+// -mgpopt
+// RUN: %clang -target mips-linux-gnu -### -c %s -mno-gpopt -mgpopt -Wno-unsupported-gpopt 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MGPOPT-DEF-ABICALLS %s
+// CHECK-MGPOPT-DEF-ABICALLS-NOT: "-mllvm" "-mgpopt"
+//
+// -mabicalls -mgpopt
+// RUN: %clang -target mips-linux-gnu -### -c %s -mabicalls -mno-gpopt -mgpopt -Wno-unsupported-gpopt 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MGPOPT-EXPLICIT-ABICALLS %s
+// CHECK-MGPOPT-EXPLICIT-ABICALLS-NOT: "-mllvm" "-mgpopt"
+//
+// -mno-abicalls -mgpopt
+// RUN: %clang -target mips-linux-gnu -### -c %s -mno-abicalls -mno-gpopt -mgpopt 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MGPOPT %s
+// CHECK-MGPOPT: "-mllvm" "-mgpopt"
+//
+// -mno-abicalls -mno-gpopt
+// RUN: %clang -target mips-linux-gnu -### -c %s -mno-abicalls -mgpopt -mno-gpopt 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MNOGPOPT %s
+// CHECK-MNOGPOPT-NOT: "-mllvm" "-mgpopt"
+//
+// -mno-abicalls
+// RUN: %clang -target mips-linux-gnu -### -c %s -mno-abicalls 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-MGPOPTDEF %s
+// CHECK-MGPOPTDEF: "-mllvm" "-mgpopt"
+//
 // -mips16
 // RUN: %clang -target mips-linux-gnu -### -c %s \
 // RUN:     -mno-mips16 -mips16 2>&1 \

clang/test/Driver/mips-gpopt-warning.c

@@ -0,0 +1,6 @@
+// REQUIRES: mips-registered-target
+// RUN: %clang -### -c -target mips-mti-elf %s -mgpopt 2>&1 | FileCheck -check-prefix=IMPLICIT %s
+// IMPLICIT: warning: ignoring '-mgpopt' option as it cannot be used with the implicit usage of-mabicalls
+
+// RUN: %clang -### -c -target mips-mti-elf %s -mgpopt -mabicalls 2>&1 | FileCheck -check-prefix=EXPLICIT %s
+// EXPLICIT: warning: ignoring '-mgpopt' option as it cannot be used with -mabicalls