Forward -target-feature option through to assembler.

[• chatur01]

Summary

The cc1as driver supports the -target-feature option, but the Clang driver refuses to forward such an option specified with -Xassembler or -Wa through to cc1as, claiming it is unrecognized. This patch makes Clang forward the target-feature option and its argument through to the assembler.

The -target-feature option is useful for enabling/disabling optional features when using Clang as an assembler. For example (assuming test.s contains appropriate content),

$ clang -c -target arm-none-eabi -mcpu=cortex-a9 -Xassembler -target-feature -Xassembler -mp test.s
# Or
$ clang -c -target arm-none-eabi -mcpu=cortex-a9 -Wa,-target-feature,-mp test.s

Would signal an error if the assembly file test.s contained any multiprocessing extension instructions, such as PLDW,

$ clang -c -target arm-none-eabi -mcpu=cortex-a9 -Xassembler -target-feature -Xassembler -mp test.s
test.s:31:2: error: instruction requires: mp-extensions
        pldw    [r0]

However, currently the behavior is,

$ clang -c -target arm-none-eabi -mcpu=cortex-a9 -Xassembler -target-feature -Xassembler -mp test.s
clang-3.6: error: unsupported argument '-target-feature' to option 'Xassembler'
clang-3.6: error: unsupported argument '-mp' to option 'Xassembler

Which I consider incorrect.

[• rafael]

We normally use -Wa,FOO to be compatible with gnu as. Is there a gnu
as option that you could use?

lib/Driver/Tools.cpp

         } else if (Value.startswith("-I")) {
           CmdArgs.push_back(Value.data());
           // We need to consume the next argument if the current arg is a plain
           // -I. The next arg will be the include directory.
           if (Value == "-I")
             TakeNextArg = true;
         } else if (Value.startswith("-gdwarf-")) {
           CmdArgs.push_back(Value.data());
+        } else if (Value == "-target-feature") {
+          CmdArgs.push_back("-target-feature");
+          TakeNextArg = true;
         } else {
           D.Diag(diag::err_drv_unsupported_option_argument)
             << A->getOption().getName() << Value;
         }
       }
     }
     if (CompressDebugSections) {
       if (llvm::zlib::isAvailable())

test/Driver/integrated-as.s

 // RUN: %clang -### -c -integrated-as %s -gdwarf-4 2>&1 | FileCheck --check-prefix=DWARF4 %s
 // DWARF4: "-g" "-gdwarf-4"
 
 // RUN: %clang -### -c -integrated-as %s -Xassembler -gdwarf-2 2>&1 | FileCheck --check-prefix=DWARF2XASSEMBLER %s
 // DWARF2XASSEMBLER: "-gdwarf-2"
 
 // RUN: %clang -### -c -integrated-as %s -Wa,-gdwarf-2 2>&1 | FileCheck --check-prefix=DWARF2WA %s
 // DWARF2WA: "-gdwarf-2"
+
+// RUN: %clang -### -c -integrated-as %s -Xassembler -target-feature -Xassembler -mp 2>&1 \
+// RUN:    | FileCheck --check-prefix=TARGET_FEATURE1 %s
+// RUN: %clang -### -c -integrated-as %s -Wa,-target-feature,-mp 2>&1 | FileCheck --check-prefix=TARGET_FEATURE1 %s
+// TARGET_FEATURE1: "-target-feature"
+// TARGET_FEATURE1: "-mp"