[ARM] Don't pass -arm-execute-only to cc1as

[christof]

Summary

The option -mexecute-only is translated into the backend option -arm-execute-only. But this option only makes sense for the compiler and the assembler does not recognize it. This patch stops clang from passing the option to the assembler.

[rengolin]

Makes sense, LGTM. Thanks!

[christof]

This landed as https://reviews.llvm.org/rL296454 some time ago. Not sure why it was not auto-closed. Closing manually.

lib/Driver/Arch/ARM.cpp

if (Arg *A = Args.getLastArg(options::OPT_mlong_calls,
     if (A->getOption().matches(options::OPT_mlong_calls))
       Features.push_back("+long-calls");
   } else if (KernelOrKext && (!Triple.isiOS() || Triple.isOSVersionLT(6)) &&
              !Triple.isWatchOS()) {
       Features.push_back("+long-calls");
   }
 
   // Generate execute-only output (no data access to code sections).
+  // This only makes sense for the compiler, not for the assembler.
+  if (!ForAS) {
     // Supported only on ARMv6T2 and ARMv7 and above.
     // Cannot be combined with -mno-movt or -mlong-calls
     if (Arg *A = Args.getLastArg(options::OPT_mexecute_only, options::OPT_mno_execute_only)) {
       if (A->getOption().matches(options::OPT_mexecute_only)) {
         if (getARMSubArchVersionNumber(Triple) < 7 &&
             llvm::ARM::parseArch(Triple.getArchName()) != llvm::ARM::AK_ARMV6T2)
               D.Diag(diag::err_target_unsupported_execute_only) << Triple.getArchName();
         else if (Arg *B = Args.getLastArg(options::OPT_mno_movt))
           D.Diag(diag::err_opt_not_valid_with_opt) << A->getAsString(Args) << B->getAsString(Args);
         // Long calls create constant pool entries and have not yet been fixed up
         // to play nicely with execute-only. Hence, they cannot be used in
         // execute-only code for now
         else if (Arg *B = Args.getLastArg(options::OPT_mlong_calls, options::OPT_mno_long_calls)) {
           if (B->getOption().matches(options::OPT_mlong_calls))
             D.Diag(diag::err_opt_not_valid_with_opt) << A->getAsString(Args) << B->getAsString(Args);
         }
 
         CmdArgs.push_back("-backend-option");
         CmdArgs.push_back("-arm-execute-only");
       }
     }
+  }
 
   // Kernel code has more strict alignment requirements.
   if (KernelOrKext)
     Features.push_back("+strict-align");
   else if (Arg *A = Args.getLastArg(options::OPT_mno_unaligned_access,
                                     options::OPT_munaligned_access)) {
     if (A->getOption().matches(options::OPT_munaligned_access)) {
       // No v6M core supports unaligned memory access (v6M ARM ARM A3.2).

test/Driver/arm-execute-only.c

 // RUN:   FileCheck --check-prefix CHECK-EXECUTE-ONLY-NOT-SUPPORTED %s
 
 // RUN: not %clang -target armv8m.main-eabi -mpure-code -mno-movt %s 2>&1 \
 // RUN:    | FileCheck %s -check-prefix CHECK-EXECUTE-ONLY-NO-MOVT
 
 // RUN: not %clang -target armv8m.main-eabi -mpure-code -mlong-calls %s 2>&1 \
 // RUN:    | FileCheck %s -check-prefix CHECK-EXECUTE-ONLY-LONG-CALLS
 
+// RUN: %clang -target armv7m-eabi -x assembler -mexecute-only %s -c -### 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-NO-EXECUTE-ONLY -check-prefix CHECK-NO-EXECUTE-ONLY-ASM
+
 //
 // CHECK-NO-EXECUTE-ONLY-NOT: "-backend-option" "-arm-execute-only"
 // CHECK-EXECUTE-ONLY: "-backend-option" "-arm-execute-only"
 
 // CHECK-EXECUTE-ONLY-NOT-SUPPORTED: error: execute only is not supported for the thumbv6m sub-architecture
 // CHECK-EXECUTE-ONLY-NO-MOVT: error: option '-mexecute-only' cannot be specified with '-mno-movt'
 // CHECK-EXECUTE-ONLY-LONG-CALLS: error: option '-mexecute-only' cannot be specified with '-mlong-calls'
+// CHECK-NO-EXECUTE-ONLY-ASM: warning: argument unused during compilation: '-mexecute-only'