From be9668675aa2c3a602f71e49da84556d9813f778 Mon Sep 17 00:00:00 2001
From: Akira Hatanaka <ahatanaka@apple.com>
Date: Thu, 23 Oct 2014 04:17:05 +0000
Subject: [PATCH] [ARM, stack protector] If supported, use armv7 instructions.

This commit enables using movt/movw to load the stack guard address:

movw r0, :lower16:(L_g3$non_lazy_ptr-(LPC0_0+8))
movt r0, :upper16:(L_g3$non_lazy_ptr-(LPC0_0+8))
ldr r0, [pc, r0]

Previously a pc-relative load was emitted:

ldr r0, LCPI0_0
ldr r0, [pc, r0]

rdar://problem/18740489


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220470 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/ARM/ARMInstrInfo.cpp       | 43 ++++++++++++++++++++++++---
 test/CodeGen/ARM/stack_guard_remat.ll | 24 +++++++++++++++
 2 files changed, 63 insertions(+), 4 deletions(-)

diff --git a/lib/Target/ARM/ARMInstrInfo.cpp b/lib/Target/ARM/ARMInstrInfo.cpp
index 512152807e3..17d1ffaa9ff 100644
--- a/lib/Target/ARM/ARMInstrInfo.cpp
+++ b/lib/Target/ARM/ARMInstrInfo.cpp
@@ -92,10 +92,45 @@ unsigned ARMInstrInfo::getUnindexedOpcode(unsigned Opc) const {
 
 void ARMInstrInfo::expandLoadStackGuard(MachineBasicBlock::iterator MI,
                                         Reloc::Model RM) const {
-  if (RM == Reloc::PIC_)
-    expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_pcrel, ARM::LDRi12, RM);
-  else
-    expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_abs, ARM::LDRi12, RM);
+  MachineFunction &MF = *MI->getParent()->getParent();
+  const ARMSubtarget &Subtarget = MF.getTarget().getSubtarget<ARMSubtarget>();
+
+  if (!Subtarget.useMovt(MF)) {
+    if (RM == Reloc::PIC_)
+      expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_pcrel, ARM::LDRi12, RM);
+    else
+      expandLoadStackGuardBase(MI, ARM::LDRLIT_ga_abs, ARM::LDRi12, RM);
+    return;
+  }
+
+  if (RM != Reloc::PIC_) {
+    expandLoadStackGuardBase(MI, ARM::MOVi32imm, ARM::LDRi12, RM);
+    return;
+  }
+
+  const GlobalValue *GV =
+      cast<GlobalValue>((*MI->memoperands_begin())->getValue());
+
+  if (!Subtarget.GVIsIndirectSymbol(GV, RM)) {
+    expandLoadStackGuardBase(MI, ARM::MOV_ga_pcrel, ARM::LDRi12, RM);
+    return;
+  }
+
+  MachineBasicBlock &MBB = *MI->getParent();
+  DebugLoc DL = MI->getDebugLoc();
+  unsigned Reg = MI->getOperand(0).getReg();
+  MachineInstrBuilder MIB;
+
+  MIB = BuildMI(MBB, MI, DL, get(ARM::MOV_ga_pcrel_ldr), Reg)
+            .addGlobalAddress(GV, 0, ARMII::MO_NONLAZY);
+  unsigned Flag = MachineMemOperand::MOLoad | MachineMemOperand::MOInvariant;
+  MachineMemOperand *MMO = MBB.getParent()->getMachineMemOperand(
+      MachinePointerInfo::getGOT(), Flag, 4, 4);
+  MIB.addMemOperand(MMO);
+  MIB = BuildMI(MBB, MI, DL, get(ARM::LDRi12), Reg);
+  MIB.addReg(Reg, RegState::Kill).addImm(0);
+  MIB.setMemRefs(MI->memoperands_begin(), MI->memoperands_end());
+  AddDefaultPred(MIB);
 }
 
 namespace {
diff --git a/test/CodeGen/ARM/stack_guard_remat.ll b/test/CodeGen/ARM/stack_guard_remat.ll
index 7dc18250d38..b11ea92b04d 100644
--- a/test/CodeGen/ARM/stack_guard_remat.ll
+++ b/test/CodeGen/ARM/stack_guard_remat.ll
@@ -1,6 +1,9 @@
 ; RUN: llc < %s -mtriple=arm-apple-ios -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC
 ; RUN: llc < %s -mtriple=arm-apple-ios -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=NO-PIC -check-prefix=STATIC
 ; RUN: llc < %s -mtriple=arm-apple-ios -relocation-model=dynamic-no-pic -no-integrated-as | FileCheck %s  -check-prefix=NO-PIC -check-prefix=DYNAMIC-NO-PIC
+; RUN: llc < %s -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=pic -no-integrated-as | FileCheck %s -check-prefix=PIC-V7
+; RUN: llc < %s -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=static -no-integrated-as | FileCheck %s -check-prefix=STATIC-V7
+; RUN: llc < %s -mtriple=armv7-apple-ios -mcpu=cortex-a8 -relocation-model=dynamic-no-pic -no-integrated-as | FileCheck %s -check-prefix=DYNAMIC-NO-PIC-V7
 
 ;PIC:   foo2
 ;PIC:   ldr [[R0:r[0-9]+]], [[LABEL0:LCPI[0-9_]+]]
@@ -23,6 +26,27 @@
 ;DYNAMIC-NO-PIC:      [[LABEL0]]:
 ;DYNAMIC-NO-PIC-NEXT:   .long L___stack_chk_guard$non_lazy_ptr
 
+;PIC-V7:   movw [[R0:r[0-9]+]], :lower16:(L___stack_chk_guard$non_lazy_ptr-([[LABEL0:LPC[0-9_]+]]+8))
+;PIC-V7:   movt [[R0]], :upper16:(L___stack_chk_guard$non_lazy_ptr-([[LABEL0]]+8))
+;PIC-V7: [[LABEL0]]:
+;PIC-V7:   ldr [[R0]], {{\[}}pc, [[R0]]{{\]}}
+;PIC-V7:   ldr [[R0]], {{\[}}[[R0]]{{\]}}
+
+;PIC-V7: L___stack_chk_guard$non_lazy_ptr:
+;PIC-V7:   .indirect_symbol        ___stack_chk_guard
+
+;STATIC-V7: movw [[R0:r[0-9]+]], :lower16:___stack_chk_guard
+;STATIC-V7: movt [[R0]], :upper16:___stack_chk_guard
+;STATIC-V7: ldr  [[R0]], {{\[}}[[R0]]{{\]}}
+
+;DYNAMIC-NO-PIC-V7: movw [[R0:r[0-9]+]], :lower16:L___stack_chk_guard$non_lazy_ptr
+;DYNAMIC-NO-PIC-V7: movt [[R0]], :upper16:L___stack_chk_guard$non_lazy_ptr
+;DYNAMIC-NO-PIC-V7: ldr  [[R0]], {{\[}}[[R0]]{{\]}}
+;DYNAMIC-NO-PIC-V7: ldr  [[R0]], {{\[}}[[R0]]{{\]}}
+
+;DYNAMIC-NO-PIC-V7: L___stack_chk_guard$non_lazy_ptr:
+;DYNAMIC-NO-PIC-V7:   .indirect_symbol        ___stack_chk_guard
+
 ; Function Attrs: nounwind ssp
 define i32 @test_stack_guard_remat() #0 {
   %a1 = alloca [256 x i32], align 4