[PPC32] Fix PLT calls for -msecure-plt -fpic

[MaskRay]

Summary

In Secure PLT ABI, -fpic is similar to -fPIC. The difference is that:

• the address of _GLOBAL_OFFSET_TABLE instead of .got2+0x8000 is stored in r30.
• R_PPC_PLTREL24 does not get an addend of 0x8000.

[MaskRay]

Update title

[MaskRay]

Fix R_*_PLTREL addend

[MaskRay]

Ping :)

[jhibbits]

Looks fine to me. @hfinkel or @nemanjai?

[MaskRay]

Update description

lib/Target/PowerPC/PPCAsmPrinter.cpp

case PPC::MovePCtoLR8: {
     OutStreamer->EmitLabel(PICBase);
     return;
   }
   case PPC::UpdateGBR: {
     // Transform %rd = UpdateGBR(%rt, %ri)
     // Into: lwz %rt, .L0$poff - .L0$pb(%ri)
     //       add %rd, %rt, %ri
     // or into (if secure plt mode is on):
-    //       addis r30, r30, .LTOC - .L0$pb@ha
-    //       addi r30, r30, .LTOC - .L0$pb@l
+    //       addis r30, r30, {.LTOC,_GLOBAL_OFFSET_TABLE} - .L0$pb@ha
+    //       addi r30, r30, {.LTOC,_GLOBAL_OFFSET_TABLE} - .L0$pb@l
     // Get the offset from the GOT Base Register to the GOT
     LowerPPCMachineInstrToMCInst(MI, TmpInst, *this, isDarwin);
     if (Subtarget->isSecurePlt() && isPositionIndependent() ) {
       unsigned PICR = TmpInst.getOperand(0).getReg();
-      MCSymbol *LTOCSymbol = OutContext.getOrCreateSymbol(StringRef(".LTOC"));
+      MCSymbol *BaseSymbol = OutContext.getOrCreateSymbol(
+          M->getPICLevel() == PICLevel::SmallPIC ? "_GLOBAL_OFFSET_TABLE_"
+                                                 : ".LTOC");
       const MCExpr *PB =
-        MCSymbolRefExpr::create(MF->getPICBaseSymbol(),
-                                OutContext);
+          MCSymbolRefExpr::create(MF->getPICBaseSymbol(), OutContext);
 
-      const MCExpr *LTOCDeltaExpr =
-        MCBinaryExpr::createSub(MCSymbolRefExpr::create(LTOCSymbol, OutContext),
-                                PB, OutContext);
+      const MCExpr *DeltaExpr = MCBinaryExpr::createSub(
+          MCSymbolRefExpr::create(BaseSymbol, OutContext), PB, OutContext);
 
-      const MCExpr *LTOCDeltaHi =
-        PPCMCExpr::createHa(LTOCDeltaExpr, false, OutContext);
-      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDIS)
-                                   .addReg(PICR)
-                                   .addReg(PICR)
-                                   .addExpr(LTOCDeltaHi));
+      const MCExpr *DeltaHi = PPCMCExpr::createHa(DeltaExpr, false, OutContext);
+      EmitToStreamer(
+          *OutStreamer,
+          MCInstBuilder(PPC::ADDIS).addReg(PICR).addReg(PICR).addExpr(DeltaHi));
 
-      const MCExpr *LTOCDeltaLo =
-        PPCMCExpr::createLo(LTOCDeltaExpr, false, OutContext);
-      EmitToStreamer(*OutStreamer, MCInstBuilder(PPC::ADDI)
-                                   .addReg(PICR)
-                                   .addReg(PICR)
-                                   .addExpr(LTOCDeltaLo));
+      const MCExpr *DeltaLo = PPCMCExpr::createLo(DeltaExpr, false, OutContext);
+      EmitToStreamer(
+          *OutStreamer,
+          MCInstBuilder(PPC::ADDI).addReg(PICR).addReg(PICR).addExpr(DeltaLo));
       return;
     } else {
       MCSymbol *PICOffset =
         MF->getInfo<PPCFunctionInfo>()->getPICOffsetSymbol();
       TmpInst.setOpcode(PPC::LWZ);
       const MCExpr *Exp =
         MCSymbolRefExpr::create(PICOffset, MCSymbolRefExpr::VK_None, OutContext);
       const MCExpr *PB =

lib/Target/PowerPC/PPCISelDAGToDAG.cpp

if (!GlobalBaseReg) {
     MachineBasicBlock &FirstMBB = MF->front();
     MachineBasicBlock::iterator MBBI = FirstMBB.begin();
     const Module *M = MF->getFunction().getParent();
     DebugLoc dl;
 
     if (PPCLowering->getPointerTy(CurDAG->getDataLayout()) == MVT::i32) {
       if (PPCSubTarget->isTargetELF()) {
         GlobalBaseReg = PPC::R30;
-        if (M->getPICLevel() == PICLevel::SmallPIC) {
+        if (!PPCSubTarget->isSecurePlt() &&
+            M->getPICLevel() == PICLevel::SmallPIC) {
           BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MoveGOTtoLR));
           BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MFLR), GlobalBaseReg);
           MF->getInfo<PPCFunctionInfo>()->setUsesPICBase(true);
         } else {
           BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MovePCtoLR));
           BuildMI(FirstMBB, MBBI, dl, TII.get(PPC::MFLR), GlobalBaseReg);
           unsigned TempReg = RegInfo->createVirtualRegister(&PPC::GPRCRegClass);
           BuildMI(FirstMBB, MBBI, dl,
case PPCISD::ADDI_TLSGD_L_ADDR: {
     // generate secure plt code for TLS symbols.
     getGlobalBaseReg();
   } break;
   case PPCISD::CALL: {
     const Module *M = MF->getFunction().getParent();
 
     if (PPCLowering->getPointerTy(CurDAG->getDataLayout()) != MVT::i32 ||
         (!TM.isPositionIndependent() || !PPCSubTarget->isSecurePlt()) ||
-        !PPCSubTarget->isTargetELF() || M->getPICLevel() == PICLevel::SmallPIC)
+        !PPCSubTarget->isTargetELF())
       break;
 
     SDValue Op = N->getOperand(1);
 
     if (GlobalAddressSDNode *GA = dyn_cast<GlobalAddressSDNode>(Op)) {
       if (GA->getTargetFlags() == PPCII::MO_PLT)
         getGlobalBaseReg();
     }

test/CodeGen/PowerPC/ppc32-pic.ll

-; RUN: llc < %s -mtriple=powerpc-unknown-linux-gnu -relocation-model=pic | FileCheck -check-prefix=SMALL-BSS %s
+; RUN: llc < %s -mtriple=powerpc -relocation-model=pic | \
+; RUN:    FileCheck -check-prefixes=SMALL,SMALL-BSS %s
+; RUN: llc < %s -mtriple=powerpc -relocation-model=pic -mattr=+secure-plt | \
+; RUN:    FileCheck -check-prefixes=SMALL,SMALL-SECUREPLT %s
 @bar = common global i32 0, align 4
 
 declare i32 @call_foo(i32, ...)
 
 define i32 @foo() {
 entry:
   %0 = load i32, i32* @bar, align 4
   %call = call i32 (i32, ...) @call_foo(i32 %0, i32 0, i32 1, i32 2, i32 4, i32 8, i32 16, i32 32, i32 64)
   ret i32 0
 }
 
 !llvm.module.flags = !{!0}
 !0 = !{i32 1, !"PIC Level", i32 1}
-; SMALL-BSS-LABEL:foo:
-; SMALL-BSS:         stwu 1, -32(1)
-; SMALL-BSS:         stw 30, 24(1)
-; SMALL-BSS:         bl _GLOBAL_OFFSET_TABLE_@local-4
-; SMALL-BSS:         mflr 30
-; SMALL-BSS-DAG:     stw {{[0-9]+}}, 8(1)
-; SMALL-BSS-DAG:     lwz [[VREG:[0-9]+]], bar@GOT(30)
-; SMALL-BSS-DAG:     lwz {{[0-9]+}}, 0([[VREG]])
-; SMALL-BSS:         bl call_foo@PLT
-; SMALL-BSS:         lwz 30, 24(1)
+; SMALL-LABEL: foo:
+; SMALL:         stwu 1, -32(1)
+; SMALL:         stw 30, 24(1)
+; SMALL-BSS:     bl _GLOBAL_OFFSET_TABLE_@local-4
+; SMALL-SECURE:  bl .L0$pb
+; SMALL:         mflr 30
+; SMALL-SECURE:  addis 30, 30, _GLOBAL_OFFSET_TABLE_-.Lo$pb@ha
+; SMALL-SECURE:  addi 30, 30, _GLOBAL_OFFSET_TABLE_-.Lo$pb@l
+; SMALL-DAG:     stw {{[0-9]+}}, 8(1)
+; SMALL-DAG:     lwz [[VREG:[0-9]+]], bar@GOT(30)
+; SMALL-DAG:     lwz {{[0-9]+}}, 0([[VREG]])
+; SMALL-BSS:     bl call_foo@PLT{{$}}
+; SMALL-SECURE:  bl call_foo@PLT+32768
+; SMALL:         lwz 30, 24(1)