[driver][mips] Enable integrated assembler for MIPS64 except N32 ABI selected

[atanasyan]

Summary

Enable integrated assembler for MIPS64 targets except N32 ABI explicitly selected by the -mabi=n32 command line option or mips64(el)-linux-gnuabin32 target triple.

[atanasyan]

Ping?

[rnk]

lgtm, sorry it got lost.

[brad]

Simon, and what about lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp?

[atanasyan]

In D52418#1256189, @brad wrote:

Simon, and what about lib/Target/Mips/MCTargetDesc/MipsMCAsmInfo.cpp?

Good point. In fact, integrated assembler for GNUABIN32 was enabled in the MipsMCAsmInfo ctor by me and by mistake. I have another patch which fix it. But anyway there is a problem - we cannot check command line options in the MipsMCAsmInfo. So I'm going to test current MIPS N32 ABI implementation. Maybe we are ready to enable integrated assembler for it. In that case both Generic_GCC::IsIntegratedAssemblerDefault() and MipsMCAsmInfo ctor can be simplified.

[brad]

IMHO it would be best to try and deal with as many known / exposed issues with the N32 support and then just enable IAS across the board. Then tackle any remaining issues as they come up.

[brad]

How is it going with regard to N32 fixes / testing?

[atanasyan]

In D52418#1271779, @brad wrote:

How is it going with regard to N32 fixes / testing?

I'm in the process of building/testing LLVM/Clang binaries for N32 ABI.

[brad]

Simon?

[atanasyan]

In D52418#1294699, @brad wrote:

Simon?

The testing continues. Unfortunately I do not have access to an appropriate hardware so cannot control the process. But the task is not abandoned.

[atanasyan]

Commits rL348934 and rL348935 enable using of integrated assembler for MIPS targets in all cases.

include/clang/Driver/ToolChain.h

protected:
   MultilibSet Multilibs;
   Multilib SelectedMultilib;
 
   ToolChain(const Driver &D, const llvm::Triple &T,
             const llvm::opt::ArgList &Args);
 
   void setTripleEnvironment(llvm::Triple::EnvironmentType Env);
 
+  const llvm::opt::ArgList &getArgs() const { return Args; };
+
   virtual Tool *buildAssembler() const;
   virtual Tool *buildLinker() const;
   virtual Tool *getTool(Action::ActionClass AC) const;
 
   /// \name Utilities for implementing subclasses.
   ///@{
   static void addSystemInclude(const llvm::opt::ArgList &DriverArgs,
                                llvm::opt::ArgStringList &CC1Args,

lib/Driver/ToolChains/Gnu.cpp

bool Generic_GCC::IsIntegratedAssemblerDefault() const {
   case llvm::Triple::riscv32:
   case llvm::Triple::riscv64:
   case llvm::Triple::systemz:
   case llvm::Triple::mips:
   case llvm::Triple::mipsel:
     return true;
   case llvm::Triple::mips64:
   case llvm::Triple::mips64el:
-    // Enabled for Debian, Android, FreeBSD and OpenBSD mips64/mipsel, as they
-    // can precisely identify the ABI in use (Debian) or only use N64 for MIPS64
-    // (Android). Other targets are unable to distinguish N32 from N64.
-    if (getTriple().getEnvironment() == llvm::Triple::GNUABI64 ||
-        getTriple().isAndroid() ||
-        getTriple().isOSFreeBSD() ||
-        getTriple().isOSOpenBSD())
-      return true;
-    return false;
+    // Do not use integrated assembler for N32 ABI only.
+    return !tools::mips::hasMipsAbiArg(getArgs(), "n32") &&
+           getTriple().getEnvironment() != llvm::Triple::GNUABIN32;
   default:
     return false;
   }
 }
 
 void Generic_GCC::AddClangCXXStdlibIncludeArgs(const ArgList &DriverArgs,
                                                ArgStringList &CC1Args) const {
   if (DriverArgs.hasArg(options::OPT_nostdlibinc) ||

test/Driver/mips-gnu-integrated-as.c

+# Check cases when MIPS cannot use the integrated assembler.
+
+# RUN: %clang -target mips-unknown-gnu -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=INT %s
+# RUN: %clang -target mipsel-unknown-gnu -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=INT %s
+# RUN: %clang -target mips64-unknown-gnu -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=INT %s
+# RUN: %clang -target mips64el-unknown-gnu -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=INT %s
+# RUN: %clang -target mips64-unknown-gnu -mabi=64 -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=INT %s
+# RUN: %clang -target mips64el-unknown-gnu -mabi=64 -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=INT %s
+
+# INT-NOT: "-no-integrated-as"
+
+# RUN: %clang -target mips64-linux-gnuabin32 -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=EXT %s
+# RUN: %clang -target mips64el-linux-gnuabin32 -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=EXT %s
+# RUN: %clang -target mips64-unknown-gnu -mabi=n32 -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=EXT %s
+# RUN: %clang -target mips64el-unknown-gnu -mabi=n32 -### -c %s 2>&1 \
+# RUN:   | FileCheck -check-prefix=EXT %s
+
+# EXT: "-no-integrated-as"