[PPC, SSP] Support PowerPC Linux stack protection using LOAD_STACK_GUARD

[timshen]

Summary

Let PowerPC handle LOAD_STACK_GUARD manually, since glibc isn't offering a __stack_chk_guard symbol, but put it in TCB.

[timshen]

Updated for only doing manual lowering on Linux (similar to X86).

[timshen]

Rebase to pick up SSP infrastructure change.

[echristo]

Hi Tim,

Other than one patch I'd like you to write first this just needs comments and you're good to go. Thanks a ton.

-eric

lib/Target/PowerPC/PPCISelLowering.cpp

12017 ↗

(On Diff #54245)

Comment explaining why on all 3 of these functions please.

lib/Target/PowerPC/PPCISelLowering.h

678

Mind going back in time and renaming this getSDagStackGuard please?

lib/Target/PowerPC/PPCInstrInfo.cpp

1849

Comments.

[timshen]

Updated and simplified.

lib/Target/PowerPC/PPCISelLowering.cpp

12017 ↗

(On Diff #54245)

Through commenting the functions, I actually simplifies them by overriding only two of them. :)

lib/Target/PowerPC/PPCInstrInfo.cpp

1849

Done in the header.

[timshen]

lib/Target/PowerPC/PPCISelLowering.cpp

12017 ↗

(On Diff #54248)

s/simplifies/simplified/. Apparently my English is broken. :P

[dblaikie]

Did this get committed? I can't seem to find the subject line anywhere &
the Differential revision isn't mentioned in a commit that I can find, etc.

[timshen]

This is committed as r266809.

lib/Target/PowerPC/PPCISelLowering.h

public:
     unsigned
     getExceptionPointerRegister(const Constant *PersonalityFn) const override;
 
     /// If a physical register, this returns the register that receives the
     /// exception typeid on entry to a landing pad.
     unsigned
     getExceptionSelectorRegister(const Constant *PersonalityFn) const override;
 
+    virtual Value *getStackGuardAddr(Module &M) const override {
+      return nullptr;
+    }
+
   private:
     struct ReuseLoadInfo {
       SDValue Ptr;
       SDValue Chain;
       SDValue ResChain;
       MachinePointerInfo MPI;
       bool IsInvariant;
       unsigned Alignment;

lib/Target/PowerPC/PPCInstrInfo.h

public:
   std::pair<unsigned, unsigned>
   decomposeMachineOperandsTargetFlags(unsigned TF) const override;
 
   ArrayRef<std::pair<unsigned, const char *>>
   getSerializableDirectMachineOperandTargetFlags() const override;
 
   ArrayRef<std::pair<unsigned, const char *>>
   getSerializableBitmaskMachineOperandTargetFlags() const override;
+
+  bool expandPostRAPseudo(MachineBasicBlock::iterator MI) const override;
 };
 
 }
 
 #endif

lib/Target/PowerPC/PPCInstrInfo.cpp

PPCInstrInfo::getSerializableBitmaskMachineOperandTargetFlags() const {
   static const std::pair<unsigned, const char *> TargetFlags[] = {
       {MO_PLT_OR_STUB, "ppc-plt-or-stub"},
       {MO_PIC_FLAG, "ppc-pic"},
       {MO_NLP_FLAG, "ppc-nlp"},
       {MO_NLP_HIDDEN_FLAG, "ppc-nlp-hidden"}};
   return makeArrayRef(TargetFlags);
 }
 
+bool PPCInstrInfo::expandPostRAPseudo(MachineBasicBlock::iterator MI) const {
+  switch (MI->getOpcode()) {
+  case TargetOpcode::LOAD_STACK_GUARD: {
+    const int64_t Offset = Subtarget.isPPC64() ? -0x7010 : -0x7008;
+    const unsigned Reg = Subtarget.isPPC64() ? PPC::X13 : PPC::R2;
+    MI->setDesc(get(PPC::LD));
+    MachineInstrBuilder(*MI->getParent()->getParent(), MI)
+        .addImm(Offset)
+        .addReg(Reg);
+    return true;
+  }
+  }
+  return false;
+}

test/CodeGen/PowerPC/stack-protector.ll

-; RUN: llc -march=ppc32 -mtriple=ppc32-unknown-linux < %s | FileCheck %s
-; CHECK: __stack_chk_guard
+; RUN: llc -march=ppc32 -mtriple=ppc32-unknown-linux < %s | FileCheck -check-prefix=PPC32 %s
+; RUN: llc -mtriple=powerpc64le-unknown-linux < %s | FileCheck -check-prefix=PPC64LE %s
+
+; PPC32: ld {{[0-9]+}}, -28680(2)
+; PPC64LE: ld {{[0-9]+}}, -28688(13)
 ; CHECK: __stack_chk_fail
 
 @"\01LC" = internal constant [11 x i8] c"buf == %s\0A\00"    ; <[11 x i8]*> [#uses=1]
 
 define void @test(i8* %a) nounwind ssp {
 entry:
   %a_addr = alloca i8*    ; <i8**> [#uses=2]
   %buf = alloca [8 x i8]    ; <[8 x i8]*> [#uses=2]