Simplify ARMTargetParser::getArchSynonym

[tyomitch]

Summary

1. The only caller, ARMTargetParser::parseArch, uses the results for an "endswith" test; so, including the "arm" prefix into the result is unnecessary.
2. Most ARMTargetParser::parseArch callers pass it the output from ARMTargetParser::getCanonicalArchName; so, make this behaviour the default. Then, including the "arm" prefix into the cases is unnecessary.

[rengolin]

There are also lots of places that are calling parseArch(getCanonical()), can you simplify them as well?

Some of them are in Clang...

lib/Support/TargetParser.cpp

371 ↗

(On Diff #27133)

The reason why I didn't do this initially is because I was calling parseArch() inside getCanonicalArchName(). Now this is safe, thanks for fixing this.

llvm/trunk/lib/Support/TargetParser.cpp

return StringSwitch<StringRef>(FPU)
     .Cases("fp5-dp-d16", "fpv5-dp-d16", "fpv5-d16")
     // FIXME: Clang uses it, but it's bogus, since neon defaults to vfpv3.
     .Case("neon-vfpv3", "neon")
     .Default(FPU);
 }
 
 StringRef ARMTargetParser::getArchSynonym(StringRef Arch) {
   return StringSwitch<StringRef>(Arch)
-    .Cases("armv6sm",  "v6sm",  "armv6s-m")
-    .Cases("armv6m",   "v6m",   "armv6-m")
-    .Cases("armv7a",   "v7a",   "armv7-a")
-    .Cases("armv7r",   "v7r",   "armv7-r")
-    .Cases("armv7m",   "v7m",   "armv7-m")
-    .Cases("armv7em",  "v7em",  "armv7e-m")
-    .Cases("armv8",    "v8",    "armv8-a")
-    .Cases("armv8a",   "v8a",   "armv8-a")
-    .Cases("armv8.1a", "v8.1a", "armv8.1-a")
-    .Cases("aarch64",  "arm64", "armv8-a")
+    .Case("v6sm", "v6s-m")
+    .Case("v6m", "v6-m")
+    .Case("v7a", "v7-a")
+    .Case("v7r", "v7-r")
+    .Case("v7m", "v7-m")
+    .Case("v7em", "v7e-m")
+    .Cases("v8", "v8a", "aarch64", "arm64", "armv8-a")
+    .Case("v8.1a", "v8.1-a")
     .Default(Arch);
 }
 
 // MArch is expected to be of the form (arm|thumb)?(eb)?(v.+)?(eb)?, but
 // (iwmmxt|xscale)(eb)? is also permitted. If the former, return
 // "v.+", if the latter, return unmodified string, minus 'eb'.
 // If invalid, return empty string.
 StringRef ARMTargetParser::getCanonicalArchName(StringRef Arch) {
for (const auto F : FPUNames) {
     if (Syn == F.Name)
       return F.ID;
   }
   return ARM::FK_INVALID;
 }
 
 // Allows partial match, ex. "v7a" matches "armv7a".
 unsigned ARMTargetParser::parseArch(StringRef Arch) {
+  Arch = getCanonicalArchName(Arch);
   StringRef Syn = getArchSynonym(Arch);
   for (const auto A : ARCHNames) {
     if (StringRef(A.Name).endswith(Syn))
       return A.ID;
   }
   return ARM::AK_INVALID;
 }
 

llvm/trunk/lib/Support/Triple.cpp

Triple Triple::get64BitArchVariant() const {
   case Triple::spir:    T.setArch(Triple::spir64);    break;
   }
   return T;
 }
 
 const char *Triple::getARMCPUForArch(StringRef MArch) const {
   if (MArch.empty())
     MArch = getArchName();
+  MArch = ARMTargetParser::getCanonicalArchName(MArch);
 
   // Some defaults are forced.
   switch (getOS()) {
   case llvm::Triple::FreeBSD:
   case llvm::Triple::NetBSD:
-    MArch = ARMTargetParser::getCanonicalArchName(MArch);
     if (!MArch.empty() && MArch == "v6")
       return "arm1176jzf-s";
     break;
   case llvm::Triple::Win32:
     // FIXME: this is invalid for WindowsCE
     return "cortex-a9";
   default:
     break;
   }
 
-  MArch = ARMTargetParser::getCanonicalArchName(MArch);
   if (MArch.empty())
     return nullptr;
 
   const char *CPU = ARMTargetParser::getDefaultCPU(MArch);
   if (CPU)
     return CPU;
 
   // If no specific architecture version is requested, return the minimum CPU