[PowerPC] Enable -fstack-clash-protection option for ppc64

[lkail]

Summary

Open -fstack-clash-protection option in clang for ppc64 arch.

[steven.zhang]

Shouldn't this be the last patch to commit after the backend supporting this feature ?

[lkail]

In D81355#2078752, @steven.zhang wrote:

Shouldn't this be the last patch to commit after the backend supporting this feature ?

Yes, I've updated the parent revision.

[steven.zhang]

LGTM.

clang/docs/ReleaseNotes.rst

 - Clang's profile files generated through ``-fprofile-instr-generate`` are using
   a fixed hashing algorithm that prevents some collision when loading
   out-of-date profile informations. Clang can still read old profile files.
 
 New Compiler Flags
 ------------------
 
 - -fstack-clash-protection will provide a protection against the stack clash
-  attack for x86 and s390x architectures through automatic probing of each page
-  of allocated stack.
+  attack for x86, s390x and ppc64 architectures through automatic probing of
+  each page of allocated stack.
 
 - -ffp-exception-behavior={ignore,maytrap,strict} allows the user to specify
   the floating-point exception behavior. The default setting is ``ignore``.
 
 - -ffp-model={precise,strict,fast} provides the user an umbrella option to
   simplify access to the many single purpose floating point options. The default
   setting is ``precise``.
 

clang/lib/Basic/Targets/PPC.h

if (LongDoubleWidth == 64)
       return "e";
     return LongDoubleFormat == &llvm::APFloat::PPCDoubleDouble()
                ? "g"
                : "u9__ieee128";
   }
   const char *getFloat128Mangling() const override { return "u9__ieee128"; }
 
   bool hasExtIntType() const override { return true; }
+
+  bool isSPRegName(StringRef RegName) const override {
+    return RegName.equals("r1") || RegName.equals("x1");
+  }
 };
 
 class LLVM_LIBRARY_VISIBILITY PPC32TargetInfo : public PPCTargetInfo {
 public:
   PPC32TargetInfo(const llvm::Triple &Triple, const TargetOptions &Opts)
       : PPCTargetInfo(Triple, Opts) {
     if (Triple.isOSAIX())
       resetDataLayout("E-m:a-p:32:32-i64:64-n32");

clang/lib/Driver/ToolChains/Clang.cpp

 
 static void RenderSCPOptions(const ToolChain &TC, const ArgList &Args,
                              ArgStringList &CmdArgs) {
   const llvm::Triple &EffectiveTriple = TC.getEffectiveTriple();
 
   if (!EffectiveTriple.isOSLinux())
     return;
 
-  if (!EffectiveTriple.isX86() && !EffectiveTriple.isSystemZ())
+  if (!EffectiveTriple.isX86() && !EffectiveTriple.isSystemZ() &&
+      !EffectiveTriple.isPPC64())
     return;
 
   if (Args.hasFlag(options::OPT_fstack_clash_protection,
                    options::OPT_fnostack_clash_protection, false))
     CmdArgs.push_back("-fstack-clash-protection");
 }
 
 static void RenderTrivialAutoVarInitOptions(const Driver &D,

clang/test/CodeGen/stack-clash-protection.c

 // Check the correct function attributes are generated
 // RUN: %clang_cc1 -triple x86_64-linux -O0 -S -emit-llvm -o- %s -fstack-clash-protection | FileCheck %s
 // RUN: %clang_cc1 -triple s390x-linux-gnu -O0 -S -emit-llvm -o- %s -fstack-clash-protection | FileCheck %s
+// RUN: %clang_cc1 -triple powerpc64le-linux-gnu -O0 -S -emit-llvm -o- %s -fstack-clash-protection | FileCheck %s
+// RUN: %clang_cc1 -triple powerpc64-linux-gnu -O0 -S -emit-llvm -o- %s -fstack-clash-protection | FileCheck %s
 
 // CHECK: define void @large_stack() #[[A:.*]] {
 void large_stack() {
   volatile int stack[20000], i;
   for (i = 0; i < sizeof(stack) / sizeof(int); ++i)
     stack[i] = i;
 }