[RISCV] Add Tag_RISCV_arch attribute by default when using clang as an assembler.

[craig.topper]

Summary

Can be disabled with -mno-default-build-attributes just like ARM.

[jrtc27]

Surprised that we didn't already do this; seems like a bit of an oversight.

clang/test/Driver/riscv-default-build-attributes.s

2

Do we use /// for non-lit/FileCheck lines like we use ;; in IR tests?

12

Gap is a bit odd

13

missing "for"

[craig.topper]

clang/test/Driver/riscv-default-build-attributes.s

2

I don't know. I copied it from ARM's test.

[craig.topper]

Address review comments

[jrtc27]

Some more... hopefully spotted everything this time, sorry

clang/test/Driver/riscv-default-build-attributes.s

1

3

= for these

3

Also aren't these indented 1 too many spaces?

20

There aren't any uses of -verify?

[craig.topper]

clang/test/Driver/riscv-default-build-attributes.s

3

Cleary I should not have copied ARM's test :(

[jrtc27]

clang/test/Driver/riscv-default-build-attributes.s

3

Yeah... :( ARM and AArch64 tests can be pretty iffy in my experience

[craig.topper]

Fix more review comments

[asb]

I'd appreciate some riscv32 RUN lines for completeness, but otherwise LGTM.

clang/lib/Driver/ToolChains/Clang.cpp

 //===-- Clang.cpp - Clang+LLVM ToolChain Implementations --------*- C++ -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 

 
 void ClangAs::AddRISCVTargetArgs(const ArgList &Args,
                                ArgStringList &CmdArgs) const {
   const llvm::Triple &Triple = getToolChain().getTriple();
   StringRef ABIName = riscv::getRISCVABI(Args, Triple);
 
   CmdArgs.push_back("-target-abi");
   CmdArgs.push_back(ABIName.data());
+
+  if (Args.hasFlag(options::OPT_mdefault_build_attributes,
+                   options::OPT_mno_default_build_attributes, true)) {
+      CmdArgs.push_back("-mllvm");
+      CmdArgs.push_back("-riscv-add-build-attributes");
+  }
 }
 
 void ClangAs::ConstructJob(Compilation &C, const JobAction &JA,
                            const InputInfo &Output, const InputInfoList &Inputs,
                            const ArgList &Args,
                            const char *LinkingOutput) const {
   ArgStringList CmdArgs;
 

clang/test/Driver/riscv-default-build-attributes.s

+//// Enabled by default for assembly
+// RUN: %clang --target=riscv64 -### %s 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-ENABLED
+
+/// Can be forced on or off for assembly.
+// RUN: %clang --target=riscv64 -### %s 2>&1 -mno-default-build-attributes \
+// RUN:    | FileCheck %s -check-prefix CHECK-DISABLED
+// RUN: %clang --target=riscv64 -### %s 2>&1 -mdefault-build-attributes \
+// RUN:    | FileCheck %s -check-prefix CHECK-ENABLED
+
+/// Option ignored for C/C++ (since we always emit hardware and ABI build
+/// attributes during codegen).
+// RUN: %clang --target=riscv64 -### -x c %s -mdefault-build-attributes 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-DISABLED
+// RUN: %clang --target=riscv64 -### -x c++ %s -mdefault-build-attributes 2>&1 \
+// RUN:    | FileCheck %s -check-prefix CHECK-DISABLED
+
+// CHECK-DISABLED-NOT: "-riscv-add-build-attributes"
+// CHECK-ENABLED: "-riscv-add-build-attributes"
+// expected-warning {{argument unused during compilation: '-mno-default-build-attributes'}}