[PowerPC] Add clang option -m[no-]prefixed

[lei]

Summary

Add user-facing front end option to turn off power10 prefixed instructions.

[nemanjai]

LGTM. Thanks.

clang/include/clang/Driver/Options.td

defm unsafe_fp_atomics : BoolOption<"m", "unsafe-fp-atomics",
   NegFlag<SetFalse>>, Group<m_Group>;
 
 def faltivec : Flag<["-"], "faltivec">, Group<f_Group>, Flags<[NoXarchOption]>;
 def fno_altivec : Flag<["-"], "fno-altivec">, Group<f_Group>, Flags<[NoXarchOption]>;
 def maltivec : Flag<["-"], "maltivec">, Group<m_ppc_Features_Group>;
 def mno_altivec : Flag<["-"], "mno-altivec">, Group<m_ppc_Features_Group>;
 def mpcrel: Flag<["-"], "mpcrel">, Group<m_ppc_Features_Group>;
 def mno_pcrel: Flag<["-"], "mno-pcrel">, Group<m_ppc_Features_Group>;
+def mprefixed: Flag<["-"], "mprefixed">, Group<m_ppc_Features_Group>;
+def mno_prefixed: Flag<["-"], "mno-prefixed">, Group<m_ppc_Features_Group>;
 def mspe : Flag<["-"], "mspe">, Group<m_ppc_Features_Group>;
 def mno_spe : Flag<["-"], "mno-spe">, Group<m_ppc_Features_Group>;
 def mefpu2 : Flag<["-"], "mefpu2">, Group<m_ppc_Features_Group>;
 def mabi_EQ_vec_extabi : Flag<["-"], "mabi=vec-extabi">, Group<m_Group>, Flags<[CC1Option]>,
   HelpText<"Enable the extended Altivec ABI on AIX (AIX only). Uses volatile and nonvolatile vector registers">,
   MarshallingInfoFlag<LangOpts<"EnableAIXExtendedAltivecABI">>;
 def mabi_EQ_vec_default : Flag<["-"], "mabi=vec-default">, Group<m_Group>, Flags<[CC1Option]>,
   HelpText<"Enable the default Altivec ABI on AIX (AIX only). Uses only volatile vector registers.">;

clang/lib/Basic/Targets/PPC.h

class LLVM_LIBRARY_VISIBILITY PPCTargetInfo : public TargetInfo {
   bool HasHTM = false;
   bool HasBPERMD = false;
   bool HasExtDiv = false;
   bool HasP9Vector = false;
   bool HasSPE = false;
   bool PairedVectorMemops = false;
   bool HasP10Vector = false;
   bool HasPCRelativeMemops = false;
+  bool HasPrefixInstrs = false;
 
 protected:
   std::string ABI;
 
 public:
   PPCTargetInfo(const llvm::Triple &Triple, const TargetOptions &)
       : TargetInfo(Triple) {
     SuitableAlign = 128;

clang/lib/Basic/Targets/PPC.cpp

for (const auto &Feature : Features) {
     } else if (Feature == "+float128") {
       HasFloat128 = true;
     } else if (Feature == "+power9-vector") {
       HasP9Vector = true;
     } else if (Feature == "+power10-vector") {
       HasP10Vector = true;
     } else if (Feature == "+pcrelative-memops") {
       HasPCRelativeMemops = true;
+    } else if (Feature == "+prefix-instrs") {
+      HasPrefixInstrs = true;
     } else if (Feature == "+spe" || Feature == "+efpu2") {
       HasSPE = true;
       LongDoubleWidth = LongDoubleAlign = 64;
       LongDoubleFormat = &llvm::APFloat::IEEEdouble();
     } else if (Feature == "-hard-float") {
       FloatABI = SoftFloat;
     } else if (Feature == "+paired-vector-memops") {
       PairedVectorMemops = true;

 // Add any Power10 specific features.
 void PPCTargetInfo::addP10SpecificFeatures(
     llvm::StringMap<bool> &Features) const {
   Features["htm"] = false; // HTM was removed for P10.
   Features["paired-vector-memops"] = true;
   Features["mma"] = true;
   Features["power10-vector"] = true;
   Features["pcrelative-memops"] = true;
+  Features["prefix-instrs"] = true;
   return;
 }
 
 // Add features specific to the "Future" CPU.
 void PPCTargetInfo::addFutureSpecificFeatures(
     llvm::StringMap<bool> &Features) const {
   return;
 }
return llvm::StringSwitch<bool>(Feature)
       .Case("htm", HasHTM)
       .Case("bpermd", HasBPERMD)
       .Case("extdiv", HasExtDiv)
       .Case("float128", HasFloat128)
       .Case("power9-vector", HasP9Vector)
       .Case("paired-vector-memops", PairedVectorMemops)
       .Case("power10-vector", HasP10Vector)
       .Case("pcrelative-memops", HasPCRelativeMemops)
+      .Case("prefix-instrs", HasPrefixInstrs)
       .Case("spe", HasSPE)
       .Case("mma", HasMMA)
       .Case("rop-protect", HasROPProtect)
       .Case("privileged", HasPrivileged)
       .Default(false);
 }
 
 void PPCTargetInfo::setFeatureEnabled(llvm::StringMap<bool> &Features,
if (Enabled) {
     if (FeatureHasVSX)
       Features["vsx"] = Features["altivec"] = true;
     if (Name == "power9-vector")
       Features["power8-vector"] = true;
     else if (Name == "power10-vector")
       Features["power8-vector"] = Features["power9-vector"] = true;
     if (Name == "pcrel")
       Features["pcrelative-memops"] = true;
+    else if (Name == "prefixed")
+      Features["prefix-instrs"] = true;
     else
       Features[Name] = true;
   } else {
     if (Name == "spe")
       Features["efpu2"] = false;
     // If we're disabling altivec or vsx go ahead and disable all of the vsx
     // features.
     if ((Name == "altivec") || (Name == "vsx"))
       Features["vsx"] = Features["direct-move"] = Features["power8-vector"] =
           Features["float128"] = Features["power9-vector"] =
               Features["paired-vector-memops"] = Features["mma"] =
                   Features["power10-vector"] = false;
     if (Name == "power8-vector")
       Features["power9-vector"] = Features["paired-vector-memops"] =
           Features["mma"] = Features["power10-vector"] = false;
     else if (Name == "power9-vector")
       Features["paired-vector-memops"] = Features["mma"] =
           Features["power10-vector"] = false;
     if (Name == "pcrel")
       Features["pcrelative-memops"] = false;
+    else if (Name == "prefixed")
+      Features["prefix-instrs"] = false;
     else
       Features[Name] = false;
   }
 }
 
 const char *const PPCTargetInfo::GCCRegNames[] = {
     "r0",  "r1",     "r2",   "r3",      "r4",      "r5",  "r6",  "r7",  "r8",
     "r9",  "r10",    "r11",  "r12",     "r13",     "r14", "r15", "r16", "r17",

clang/test/Driver/ppc-prefixed.cpp

+// RUN: %clang -target powerpc64-unknown-linux-gnu %s -### -mcpu=pwr10 -mprefixed -o %t.o 2>&1 | FileCheck -check-prefix=CHECK-PREFIXED %s
+// RUN: %clang -target powerpc64-unknown-linux-gnu %s -### -mcpu=pwr10 -mno-prefixed -o %t.o 2>&1 | FileCheck -check-prefix=CHECK-NOPREFIXED %s
+// CHECK-NOPREFIXED: "-target-feature" "-prefixed"
+// CHECK-PREFIXED: "-target-feature" "+prefixed"
+
+// RUN: %clang -target powerpc64-unknown-linux-gnu -mcpu=pwr10 -emit-llvm -S %s -o - | grep "attributes.*+prefix-instrs"
+// RUN: %clang -target powerpc64-unknown-linux-gnu -mcpu=pwr10 -mprefixed -emit-llvm -S %s -o - | grep "attributes.*+prefix-instrs"
+// RUN: %clang -target powerpc64-unknown-linux-gnu -mcpu=pwr10 -mno-prefixed -emit-llvm -S %s -o - | grep "attributes.*\-prefix-instrs"
+
+int main(int argc, char *argv[]) {
+  return 0;
+}