[mips] Compact branch policy setting.

This patch adds the commandline option -mcompact-branches={never,optimal,always),
which controls how LLVM generates compact branches for MIPSR6 targets. By default,
the compact branch policy is 'optimal' where LLVM will generate the most
appropriate branch for any situation. The 'never' and 'always' policy will disable
or always generate compact branches wherever possible respectfully.

Reviewers: dsanders, vkalintiris, atanasyan

Differential Revision: http://reviews.llvm.org/D20729

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@271000 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/UsersManual.rst b/docs/UsersManual.rst
index b88a418d89043f14cf7138d98f176097006c9dee..64ae4661d2b0acbf99ec86bc8859ea15b54d4aae 100644 (file)
--- a/docs/UsersManual.rst
+++ b/docs/UsersManual.rst
@@ -1140,6 +1140,16 @@ are listed below.
    This option restricts the generated code to use general registers
    only. This only applies to the AArch64 architecture.
 
+.. option:: -mcompact-branches=[values]
+
+   Control the usage of compact branches for MIPSR6.
+
+   Valid values are: ``never``, ``optimal`` and ``always``.
+   The default value is ``optimal`` which generates compact branches
+   when a delay slot cannot be filled. ``never`` disables the usage of
+   compact branches and ``always`` generates compact branches whenever
+   possible.
+
 **-f[no-]max-type-align=[number]**
    Instruct the code generator to not enforce a higher alignment than the given
    number (of bytes) when accessing memory via an opaque pointer or reference.

diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td
index 80114645db7bd866646bd1cbcb112cab9f9a63c2..c1d221e178f622d80e97318f3f70228ed0246d05 100644 (file)
--- a/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/include/clang/Basic/DiagnosticDriverKinds.td
@@ -238,6 +238,9 @@ def warn_target_unsupported_nan2008 : Warning<
 def warn_target_unsupported_nanlegacy : Warning<
   "ignoring '-mnan=legacy' option because the '%0' architecture does not support it">,
   InGroup<UnsupportedNan>;
+def warn_target_unsupported_compact_branches : Warning<
+  "ignoring '-mcompact-branches=' option because the '%0' architecture does not"
+  " support it">, InGroup<UnsupportedCB>;
 
 def warn_drv_unable_to_find_directory_expected : Warning<
   "unable to find %0 directory, expected to be in '%1'">,

diff --git a/include/clang/Basic/DiagnosticGroups.td b/include/clang/Basic/DiagnosticGroups.td
index 73df8998cd68139ed705cc2f3515e818ee001490..979c81f6361b6d26fa69aeca96043f767344742e 100644 (file)
--- a/include/clang/Basic/DiagnosticGroups.td
+++ b/include/clang/Basic/DiagnosticGroups.td
@@ -56,6 +56,7 @@ def FloatConversion :
 def DoublePromotion : DiagGroup<"double-promotion">;
 def EnumTooLarge : DiagGroup<"enum-too-large">;
 def UnsupportedNan : DiagGroup<"unsupported-nan">;
+def UnsupportedCB : DiagGroup<"unsupported-cb">;
 def NonLiteralNullConversion : DiagGroup<"non-literal-null-conversion">;
 def NullConversion : DiagGroup<"null-conversion">;
 def ImplicitConversionFloatingPointToBool :

diff --git a/include/clang/Driver/Options.td b/include/clang/Driver/Options.td
index db9abbb9b992ba55d65980443d72b191486fd75d..c51acb89fab1b0e85e68a1fa6a57d26479e4e9c8 100644 (file)
--- a/include/clang/Driver/Options.td
+++ b/include/clang/Driver/Options.td
@@ -1621,6 +1621,7 @@ def mno_ldc1_sdc1 : Flag<["-"], "mno-ldc1-sdc1">, Group<m_Group>;
 def mcheck_zero_division : Flag<["-"], "mcheck-zero-division">, Group<m_Group>;
 def mno_check_zero_division : Flag<["-"], "mno-check-zero-division">,
                               Group<m_Group>;
+def mcompact_branches_EQ : Joined<["-"], "mcompact-branches=">, Group<m_Group>;
 def mdsp : Flag<["-"], "mdsp">, Group<m_Group>;
 def mno_dsp : Flag<["-"], "mno-dsp">, Group<m_Group>;
 def mdspr2 : Flag<["-"], "mdspr2">, Group<m_Group>;

diff --git a/lib/Driver/Tools.cpp b/lib/Driver/Tools.cpp
index 33de18d7104e3936988f160801b2b1a742910b27..95f0a80140d2c89b1cca89b0fa124c2606fc7c37 100644 (file)
--- a/lib/Driver/Tools.cpp
+++ b/lib/Driver/Tools.cpp
@@ -1436,6 +1436,19 @@ void Clang::AddMIPSTargetArgs(const ArgList &Args,
     CmdArgs.push_back(Args.MakeArgString("-mips-ssection-threshold=" + v));
     A->claim();
   }
+
+  if (Arg *A = Args.getLastArg(options::OPT_mcompact_branches_EQ)) {
+    StringRef Val = StringRef(A->getValue());
+    if (mips::hasCompactBranches(CPUName)) {
+      if (Val == "never" || Val == "always" || Val == "optimal") {
+        CmdArgs.push_back("-mllvm");
+        CmdArgs.push_back(Args.MakeArgString("-mips-compact-branches=" + Val));
+      } else
+        D.Diag(diag::err_drv_unsupported_option_argument)
+            << A->getOption().getName() << Val;
+    } else
+      D.Diag(diag::warn_target_unsupported_compact_branches) << CPUName;
+  }
 }
 
 /// getPPCTargetCPU - Get the (LLVM) name of the PowerPC cpu we are targeting.
@@ -7065,6 +7078,14 @@ mips::NanEncoding mips::getSupportedNanEncoding(StringRef &CPU) {
       .Default(NanLegacy);
 }
 
+bool mips::hasCompactBranches(StringRef &CPU) {
+  // mips32r6 and mips64r6 have compact branches.
+  return llvm::StringSwitch<bool>(CPU)
+      .Case("mips32r6", true)
+      .Case("mips64r6", true)
+      .Default(false);
+}
+
 bool mips::hasMipsAbiArg(const ArgList &Args, const char *Value) {
   Arg *A = Args.getLastArg(options::OPT_mabi_EQ);
   return A && (A->getValue() == StringRef(Value));

diff --git a/lib/Driver/Tools.h b/lib/Driver/Tools.h
index c2114bcfa8503b67fec11d8977c2fa7f243cc6c8..2e546fc653852f070d8130ea04c895b4b30b8195 100644 (file)
--- a/lib/Driver/Tools.h
+++ b/lib/Driver/Tools.h
@@ -291,6 +291,7 @@ enum class FloatABI {
 };
 
 NanEncoding getSupportedNanEncoding(StringRef &CPU);
+bool hasCompactBranches(StringRef &CPU);
 void getMipsCPUAndABI(const llvm::opt::ArgList &Args,
                       const llvm::Triple &Triple, StringRef &CPUName,
                       StringRef &ABIName);

diff --git a/test/Driver/mips-features.c b/test/Driver/mips-features.c
index 461d778182bedda23f4c524058b16dd449b32628..69fc20e1f245e449f354f2902618d3d58b2583b1 100644 (file)
--- a/test/Driver/mips-features.c
+++ b/test/Driver/mips-features.c
@@ -116,6 +116,24 @@
 // RUN:   | FileCheck --check-prefix=CHECK-NANLEGACY %s
 // CHECK-NANLEGACY: "-target-feature" "-nan2008"
 //
+// -mcompact-branches=never
+// RUN: %clang -target mips-linux-gnu -march=mips32r6 -### -c %s \
+// RUN:     -mcompact-branches=never 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-CBNEVER %s
+// CHECK-CBNEVER: "-mllvm" "-mips-compact-branches=never"
+//
+// -mcompact-branches=optimal
+// RUN: %clang -target mips-linux-gnu -march=mips32r6 -### -c %s \
+// RUN:     -mcompact-branches=optimal 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-CBOPTIMAL %s
+// CHECK-CBOPTIMAL: "-mllvm" "-mips-compact-branches=optimal"
+//
+// -mcompact-branches=always
+// RUN: %clang -target mips-linux-gnu -march=mips32r6 -### -c %s \
+// RUN:     -mcompact-branches=always 2>&1 \
+// RUN:   | FileCheck --check-prefix=CHECK-CBALWAYS %s
+// CHECK-CBALWAYS: "-mllvm" "-mips-compact-branches=always"
+//
 // -mxgot
 // RUN: %clang -target mips-linux-gnu -### -c %s \
 // RUN:     -mno-xgot -mxgot 2>&1 \