[clang][ARM] When handling multiple -mimplicit-it mark all as used

[DavidSpickett]

Summary

Since 4468e5b8999291cc84b78f33f207dcd0e58146bc clang will prefer
the last one it finds of "-mimplicit-it" or "-Wa,-mimplicit-it".

Due to a mistake in that patch the compiler argument "-mimplicit-it"
was never marked as used, even if it was the last one and was passed
to llvm.

Move the Claim call back to the start of the loop and update
the testing to check we don't get any unused argument warnings.

[DavidSpickett]

You could argue that one of them is actually "unused" but I tried -march which also takes the last value and that does not warn when it ignores earlier values.

Should've spotted it in review really but hey, simple fix.

[mstorsjo]

LGTM, and sorry for not testning this aspect in the updated version of the patch.

clang/lib/Driver/ToolChains/Clang.cpp

static void CollectArgsForIntegratedAssembler(Compilation &C,
 
   bool UseRelaxRelocations = C.getDefaultToolChain().useRelaxRelocations();
   bool UseNoExecStack = C.getDefaultToolChain().isNoExecStackDefault();
   const char *MipsTargetFeature = nullptr;
   StringRef ImplicitIt;
   for (const Arg *A :
        Args.filtered(options::OPT_Wa_COMMA, options::OPT_Xassembler,
                      options::OPT_mimplicit_it_EQ)) {
+    A->claim();
+
     if (A->getOption().getID() == options::OPT_mimplicit_it_EQ) {
       switch (C.getDefaultToolChain().getArch()) {
       case llvm::Triple::arm:
       case llvm::Triple::armeb:
       case llvm::Triple::thumb:
       case llvm::Triple::thumbeb:
         // Only store the value; the last value set takes effect.
         ImplicitIt = A->getValue();
         if (!CheckARMImplicitITArg(ImplicitIt))
           D.Diag(diag::err_drv_unsupported_option_argument)
               << A->getOption().getName() << ImplicitIt;
         continue;
       default:
         break;
       }
     }
 
-    A->claim();
-
     for (StringRef Value : A->getValues()) {
       if (TakeNextArg) {
         CmdArgs.push_back(Value.data());
         TakeNextArg = false;
         continue;
       }
 
       if (C.getDefaultToolChain().getTriple().isOSBinFormatCOFF() &&

clang/test/Driver/arm-target-as-mimplicit-it.s

 
 /// Test invalid input.
 // RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=foo %s 2>&1 | FileCheck %s --check-prefix=INVALID
 // RUN: %clang -target arm-linux-gnueabi -### -Xassembler -mimplicit-it=foo %s 2>&1 | FileCheck %s --check-prefix=XINVALID
 // RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=always -Wa,-mimplicit-it=foo %s 2>&1 | FileCheck %s --check-prefix=INVALID
 // RUN: %clang -target arm-linux-gnueabi -### -Wa,-mimplicit-it=always,-mimplicit-it=foo %s 2>&1 | FileCheck %s --check-prefix=INVALID
 
 
+/// Check that the argument we ignore is still marked as used.
+// ALWAYS-NOT: warning: argument unused during compilation: {{.*}}-mimplicit-it={{.*}}
 /// Check that there isn't a second -arm-implicit-it before or after the one
 /// that was the indended match.
 // ALWAYS-NOT: "-arm-implicit-it={{.*}}"
 // ALWAYS: "-mllvm" "-arm-implicit-it=always"
 // ALWAYS-NOT: "-arm-implicit-it={{.*}}"
 // NEVER-NOT: "-arm-implicit-it={{.*}}"
 // NEVER: "-mllvm" "-arm-implicit-it=never"
 // NEVER-NOT: "-arm-implicit-it={{.*}}"
 // ARM: "-mllvm" "-arm-implicit-it=arm"
 // THUMB: "-mllvm" "-arm-implicit-it=thumb"
 // INVALID: error: unsupported argument '-mimplicit-it=foo' to option 'Wa,'
 // XINVALID: error: unsupported argument '-mimplicit-it=foo' to option 'Xassembler'