[X86] Extend some Linux special cases to cover kFreeBSD.

[• koriakin]

Summary

Both Linux and kFreeBSD use glibc, so follow similiar code paths.
Add isTargetGlibc to check for this, and use it instead of isTargetLinux
in a few places.

Fixes PR22248 for kFreeBSD.

[• koriakin]

Updated due to a conflict with r266806.

[RKSimon]

Please can you recreate as a full diff to get more context?

http://llvm.org/docs/Phabricator.html explains how you normally should aim to create your diff with something like

svn diff --diff-cmd=diff -x -U999999

[• koriakin]

In D19104#410433, @RKSimon wrote:

Please can you recreate as a full diff to get more context?

http://llvm.org/docs/Phabricator.html explains how you normally should aim to create your diff with something like

svn diff --diff-cmd=diff -x -U999999

Uh? diff #2 already has full context, do you want to see full context for the obsolete diff too (I messed up on that one)?

[RKSimon]

In D19104#410455, @koriakin wrote:

Uh? diff #2 already has full context, do you want to see full context for the obsolete diff too (I messed up on that one)?

My mistake - was looking at an old tab somehow.

[• koriakin]

Ping?

[RKSimon]

lib/Target/X86/X86ISelLowering.cpp

2004

Add comments detailing the glibc requirement? A reference if possible similar to the diff anove in X86ISelDAGToDAG.cpp.

2017

Add comments detailing the glibc requirement?

lib/Target/X86/X86Subtarget.cpp

234

Your comment lists the OS types and then you use the GLibc helper - would it be clearer to add a isTargetkFreeBSD() to the if() instead?

An alternative would be to update the comment to make it clear that glibc x86 32-bit targets always have 16-byte alignment, but I'm not sure if that is actually true? If it is, please add a reference.

Additionally, this needs to be tested - I don't think the stack protector tests cover this.

[RKSimon]

LGTM

include/llvm/ADT/Triple.h

     return getOS() == Triple::Linux;
   }
 
+  /// Tests whether the OS uses glibc.
+  bool isOSGlibc() const {
+    return getOS() == Triple::Linux || getOS() == Triple::KFreeBSD;
+  }
+
   /// Tests whether the OS uses the ELF binary format.
   bool isOSBinFormatELF() const {
     return getObjectFormat() == Triple::ELF;

lib/Target/X86/X86ISelDAGToDAG.cpp

   // For more information see http://people.redhat.com/drepper/tls.pdf
   if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Address))
     if (C->getSExtValue() == 0 && AM.Segment.getNode() == nullptr &&
-        Subtarget->isTargetLinux())
+        Subtarget->isTargetGlibc())
       switch (N->getPointerInfo().getAddrSpace()) {
       case 256:
         AM.Segment = CurDAG->getRegister(X86::GS, MVT::i16);

lib/Target/X86/X86ISelLowering.cpp

 }
 
 Value *X86TargetLowering::getIRStackGuard(IRBuilder<> &IRB) const {
-  if (!Subtarget.isTargetLinux())
+  if (!Subtarget.isTargetGlibc())
     return TargetLowering::getIRStackGuard(IRB);
 
   // %fs:0x28, unless we're using a Kernel code model, in which case it's %gs:

 }
 
 void X86TargetLowering::insertSSPDeclarations(Module &M) const {
-  if (!Subtarget.isTargetLinux())
+  if (!Subtarget.isTargetGlibc())
     TargetLowering::insertSSPDeclarations(M);
   else
-    llvm_unreachable("X86 Linux supports customized IR stack guard load");
+    llvm_unreachable("X86 glibc supports customized IR stack guard load");
 }
 
 Value *X86TargetLowering::getSDStackGuard(const Module &M) const {
-  if (!Subtarget.isTargetLinux())
+  if (!Subtarget.isTargetGlibc())
     return TargetLowering::getSDStackGuard(M);
-  llvm_unreachable("X86 Linux supports customized IR stack guard load");
+  llvm_unreachable("X86 glibc supports customized IR stack guard load");
 }
 
 Value *X86TargetLowering::getSafeStackPointerLocation(IRBuilder<> &IRB) const {

lib/Target/X86/X86Subtarget.h

   bool isTargetMachO() const { return TargetTriple.isOSBinFormatMachO(); }
 
   bool isTargetLinux() const { return TargetTriple.isOSLinux(); }
+  bool isTargetGlibc() const { return TargetTriple.isOSGlibc(); }
   bool isTargetAndroid() const { return TargetTriple.isAndroid(); }
   bool isTargetNaCl() const { return TargetTriple.isOSNaCl(); }
   bool isTargetNaCl32() const { return isTargetNaCl() && !is64Bit(); }

lib/Target/X86/X86Subtarget.cpp

   assert((!In64BitMode || HasX86_64) &&
          "64-bit code requested on a subtarget that doesn't support it!");
 
-  // Stack alignment is 16 bytes on Darwin, Linux and Solaris (both
+  // Stack alignment is 16 bytes on Darwin, Linux, kFreeBSD and Solaris (both
   // 32 and 64 bit) and for all 64-bit targets.
   if (StackAlignOverride)
     stackAlignment = StackAlignOverride;
-  else if (isTargetDarwin() || isTargetLinux() || isTargetSolaris() ||
+  else if (isTargetDarwin() || isTargetGlibc() || isTargetSolaris() ||
            In64BitMode)
     stackAlignment = 16;
 }

test/CodeGen/X86/stack-protector-target.ll

 ; RUN: llc -mtriple=x86_64-linux < %s -o - | FileCheck --check-prefix=LINUX-X64 %s
 ; RUN: llc -mtriple=i386-linux-android < %s -o - | FileCheck --check-prefix=LINUX-I386 %s
 ; RUN: llc -mtriple=x86_64-linux-android < %s -o - | FileCheck --check-prefix=LINUX-X64 %s
+; RUN: llc -mtriple=i386-kfreebsd < %s -o - | FileCheck --check-prefix=LINUX-I386 %s
+; RUN: llc -mtriple=x86_64-kfreebsd < %s -o - | FileCheck --check-prefix=LINUX-X64 %s
 
 define void @_Z1fv() sspreq {
 entry: