[ARM] Adjust -march checking

[john.brawn]

Summary

getCanonicalArchName can return an empty string for an architecture that is well-formed but meaningless. Use parseArch to determine if it's actually valid or not.

[rengolin]

Good catch, thanks! LGTM.

lib/Driver/Tools.cpp

static void getARMTargetFeatures(const Driver &D, const llvm::Triple &Triple,
   }
 
   // Honor -mfpu=.
   if (const Arg *A = Args.getLastArg(options::OPT_mfpu_EQ))
     getARMFPUFeatures(D, A, Args, Features);
   if (const Arg *A = Args.getLastArg(options::OPT_mhwdiv_EQ))
     getARMHWDivFeatures(D, A, Args, Features);
 
-  // Check if -march is valid by checking if it can be canonicalised. getARMArch
-  // is used here instead of just checking the -march value in order to handle
-  // -march=native correctly.
+  // Check if -march is valid by checking if it can be canonicalised and parsed.
+  // getARMArch is used here instead of just checking the -march value in order
+  // to handle -march=native correctly.
   if (const Arg *A = Args.getLastArg(options::OPT_march_EQ)) {
     StringRef Arch = arm::getARMArch(Args, Triple);
-    if (llvm::ARMTargetParser::getCanonicalArchName(Arch).empty())
+    Arch = llvm::ARMTargetParser::getCanonicalArchName(Arch);
+    if (llvm::ARMTargetParser::parseArch(Arch) == llvm::ARM::AK_INVALID)
       D.Diag(diag::err_drv_clang_unsupported) << A->getAsString(Args);
   }
 
   // We do a similar thing with -mcpu, but here things are complicated because
   // the only function we have to check if a cpu is valid is
   // getLLVMArchSuffixForARM which also needs an architecture.
   if (const Arg *A = Args.getLastArg(options::OPT_mcpu_EQ)) {
     StringRef CPU = arm::getARMTargetCPU(Args, Triple);

test/Driver/arm-cortex-cpus.c

 // RUN: %clang -target arm -march=armebv8.1-a -mbig-endian -mthumb -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-BE-V81A-THUMB %s
 // CHECK-BE-V81A-THUMB: "-cc1"{{.*}} "-triple" "thumbebv8.1a-{{.*}}" "-target-cpu" "generic" "-target-feature" "+v8.1a"
 
 // ================== Check that a bogus architecture gives an error
 // RUN: %clang -target arm -march=armbogusv6 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-BOGUS %s
 // CHECK-BOGUS: error: {{.*}} does not support '-march=armbogusv6' 
 // RUN: %clang -target arm---eabihf -march=armbogusv7 -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-BOGUS-HF %s
 // CHECK-BOGUS-HF: error: {{.*}} does not support '-march=armbogusv7' 
+// RUN: %clang -target arm -march=armv6bogus -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-BOGUS2 %s
+// CHECK-BOGUS2: error: {{.*}} does not support '-march=armv6bogus'
+// RUN: %clang -target arm -march=bogus -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-BOGUS3 %s
+// CHECK-BOGUS3: error: {{.*}} does not support '-march=bogus'
 
 // ================== Check that a bogus CPU gives an error
 // RUN: %clang -target arm -mcpu=bogus -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-BOGUS-CPU %s
 // CHECK-BOGUS-CPU: error: {{.*}} does not support '-mcpu=bogus'
 
 // ================== Check default Architecture on each ARM11 CPU
 // RUN: %clang -target arm-linux-gnueabi -mcpu=arm1136j-s -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV6 %s
 // RUN: %clang -target arm-linux-gnueabi -mcpu=arm1136jf-s -### -c %s 2>&1 | FileCheck -check-prefix=CHECK-CPUV6 %s