[clang] [Windows] Mark PIC as implicitly enabled for aarch64, just like for x86_64

[mstorsjo]

Summary

This doesn't practically affect the code generation.

[MaskRay]

Looks great!

[MaskRay]

clang/test/Driver/pic.c

322

perhaps change windows-pic.cpp instead

[mstorsjo]

clang/test/Driver/pic.c

322

That file actually doesn't test the thing that this patch touches (if I remove the existing cases for x86_64 in the modified functions, that test still passes but this one breaks), so I thought this one is a better fit, wrt what the test actually tests.

[MaskRay]

I was thinking of when testing "windows" x "pic", whether the test should reside in "windows" or "pic".
If in "windows", we can decrease the number of RUN lines and use one RUN line to test multiple properties at one time.
If in "pic", it does make it clear what platforms default to pic but I think many platforms have dedicated tests and duplicate the coverage here anyway.

[mstorsjo]

In D111707#3062361, @MaskRay wrote:

I was thinking of when testing "windows" x "pic", whether the test should reside in "windows" or "pic".
If in "windows", we can decrease the number of RUN lines and use one RUN line to test multiple properties at one time.
If in "pic", it does make it clear what platforms default to pic but I think many platforms have dedicated tests and duplicate the coverage here anyway.

True, but then again, this avoids needing to duplicate the PIC level checks across two files. It costs a couple more RUN lines, true...

Anyway, I'm not strongly opposed to restructuring it, but feel free to pick that up as a followup if you want to - I'd rather keep this one as-is.

[MaskRay]

In D111707#3062384, @mstorsjo wrote:

In D111707#3062361, @MaskRay wrote:

I was thinking of when testing "windows" x "pic", whether the test should reside in "windows" or "pic".
If in "windows", we can decrease the number of RUN lines and use one RUN line to test multiple properties at one time.
If in "pic", it does make it clear what platforms default to pic but I think many platforms have dedicated tests and duplicate the coverage here anyway.

True, but then again, this avoids needing to duplicate the PIC level checks across two files. It costs a couple more RUN lines, true...

Anyway, I'm not strongly opposed to restructuring it, but feel free to pick that up as a followup if you want to - I'd rather keep this one as-is.

LG

clang/lib/Driver/ToolChains/MSVC.cpp

bool MSVCToolChain::IsUnwindTablesDefault(const ArgList &Args) const {
   // All non-x86_32 Windows targets require unwind tables. However, LLVM
   // doesn't know how to generate them for all targets, so only enable
   // the ones that are actually implemented.
   return getArch() == llvm::Triple::x86_64 ||
          getArch() == llvm::Triple::aarch64;
 }
 
 bool MSVCToolChain::isPICDefault() const {
-  return getArch() == llvm::Triple::x86_64;
+  return getArch() == llvm::Triple::x86_64 ||
+         getArch() == llvm::Triple::aarch64;
 }
 
 bool MSVCToolChain::isPIEDefault() const {
   return false;
 }
 
 bool MSVCToolChain::isPICDefaultForced() const {
-  return getArch() == llvm::Triple::x86_64;
+  return getArch() == llvm::Triple::x86_64 ||
+         getArch() == llvm::Triple::aarch64;
 }
 
 void MSVCToolChain::AddCudaIncludeArgs(const ArgList &DriverArgs,
                                        ArgStringList &CC1Args) const {
   CudaInstallation.AddCudaIncludeArgs(DriverArgs, CC1Args);
 }
 
 void MSVCToolChain::AddHIPIncludeArgs(const ArgList &DriverArgs,

clang/lib/Driver/ToolChains/MinGW.cpp

bool toolchains::MinGW::IsUnwindTablesDefault(const ArgList &Args) const {
   if (ExceptionArg &&
       ExceptionArg->getOption().matches(options::OPT_fseh_exceptions))
     return true;
   return getArch() == llvm::Triple::x86_64 ||
          getArch() == llvm::Triple::aarch64;
 }
 
 bool toolchains::MinGW::isPICDefault() const {
-  return getArch() == llvm::Triple::x86_64;
+  return getArch() == llvm::Triple::x86_64 ||
+         getArch() == llvm::Triple::aarch64;
 }
 
 bool toolchains::MinGW::isPIEDefault() const { return false; }
 
 bool toolchains::MinGW::isPICDefaultForced() const {
-  return getArch() == llvm::Triple::x86_64;
+  return getArch() == llvm::Triple::x86_64 ||
+         getArch() == llvm::Triple::aarch64;
 }
 
 llvm::ExceptionHandling
 toolchains::MinGW::GetExceptionModel(const ArgList &Args) const {
   if (getArch() == llvm::Triple::x86_64 || getArch() == llvm::Triple::aarch64)
     return llvm::ExceptionHandling::WinEH;
   return llvm::ExceptionHandling::DwarfCFI;
 }

clang/test/Driver/pic.c

 // RUN:   | FileCheck %s --check-prefix=CHECK-PIE2
 // RUN: %clang -c %s -target i686-linux-android16 -fno-PIE -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
 // RUN: %clang -c %s -target aarch64-linux-android -fno-PIE -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
 // RUN: %clang -c %s -target aarch64-linux-android24 -fno-PIE -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-NO-PIC
 //
-// On Windows-X64 PIC is enabled by default
+// On Windows x86_64 and aarch64 PIC is enabled by default
 // RUN: %clang -c %s -target x86_64-pc-windows-msvc18.0.0 -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
 // RUN: %clang -c %s -target x86_64-pc-windows-gnu -### 2>&1 \
 // RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
+// RUN: %clang -c %s -target aarch64-windows-msvc -### 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-PIC2
+// RUN: %clang -c %s -target aarch64-windows-gnu -### 2>&1 \
+// RUN:   | FileCheck %s --check-prefix=CHECK-PIC2