ARM: use r7 as the frame-pointer on all MachO targets.

This is better for a few reasons:
  + It matches the other tooling for iOS.
  + It matches EABI in more cases (i.e. Thumb-mode, and in practice we don't
    use ARM mode).
  + It leads to infinitesimally smaller code (0.2%, yay!).

rdar://25369506

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266003 91177308-0d34-0410-b5e6-96231b3b80d8

Author: TNorthover

lib/Target/ARM/ARMBaseRegisterInfo.cpp

@@ -49,12 +49,9 @@ ARMBaseRegisterInfo::ARMBaseRegisterInfo()
     : ARMGenRegisterInfo(ARM::LR, 0, 0, ARM::PC), BasePtr(ARM::R6) {}
 
 static unsigned getFramePointerReg(const ARMSubtarget &STI) {
-  if (STI.isTargetMachO()) {
-    if (STI.isTargetDarwin() || STI.isThumb1Only())
-      return ARM::R7;
-    else
-      return ARM::R11;
-  } else if (STI.isTargetWindows())
+  if (STI.isTargetMachO())
+    return ARM::R7;
+  else if (STI.isTargetWindows())
     return ARM::R11;
   else // ARM EABI
     return STI.isThumb() ? ARM::R7 : ARM::R11;

lib/Target/ARM/ARMFrameLowering.cpp

@@ -355,7 +355,7 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
     case ARM::R10:
     case ARM::R11:
     case ARM::R12:
-      if (STI.isTargetDarwin()) {
+      if (STI.isTargetMachO()) {
         GPRCS2Size += 4;
         break;
       }
@@ -559,7 +559,7 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
       case ARM::R10:
       case ARM::R11:
       case ARM::R12:
-        if (STI.isTargetDarwin())
+        if (STI.isTargetMachO())
           break;
         // fallthrough
       case ARM::R0:
@@ -592,7 +592,7 @@ void ARMFrameLowering::emitPrologue(MachineFunction &MF,
       case ARM::R10:
       case ARM::R11:
       case ARM::R12:
-        if (STI.isTargetDarwin()) {
+        if (STI.isTargetMachO()) {
           unsigned DwarfReg =  MRI->getDwarfRegNum(Reg, true);
           unsigned Offset = MFI->getObjectOffset(FI);
           unsigned CFIIndex = MMI.addFrameInst(
@@ -904,7 +904,7 @@ void ARMFrameLowering::emitPushInst(MachineBasicBlock &MBB,
     unsigned LastReg = 0;
     for (; i != 0; --i) {
       unsigned Reg = CSI[i-1].getReg();
-      if (!(Func)(Reg, STI.isTargetDarwin())) continue;
+      if (!(Func)(Reg, STI.isTargetMachO())) continue;
 
       // D-registers in the aligned area DPRCS2 are NOT spilled here.
       if (Reg >= ARM::D8 && Reg < ARM::D8 + NumAlignedDPRCS2Regs)
@@ -991,7 +991,7 @@ void ARMFrameLowering::emitPopInst(MachineBasicBlock &MBB,
     bool DeleteRet = false;
     for (; i != 0; --i) {
       unsigned Reg = CSI[i-1].getReg();
-      if (!(Func)(Reg, STI.isTargetDarwin())) continue;
+      if (!(Func)(Reg, STI.isTargetMachO())) continue;
 
       // The aligned reloads from area DPRCS2 are not inserted here.
       if (Reg >= ARM::D8 && Reg < ARM::D8 + NumAlignedDPRCS2Regs)
@@ -1545,7 +1545,7 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
     if (Spilled) {
       NumGPRSpills++;
 
-      if (!STI.isTargetDarwin()) {
+      if (!STI.isTargetMachO()) {
         if (Reg == ARM::LR)
           LRSpilled = true;
         CS1Spilled = true;
@@ -1567,7 +1567,7 @@ void ARMFrameLowering::determineCalleeSaves(MachineFunction &MF,
         break;
       }
     } else {
-      if (!STI.isTargetDarwin()) {
+      if (!STI.isTargetMachO()) {
         UnspilledCS1GPRs.push_back(Reg);
         continue;
       }

test/CodeGen/ARM/interrupt-attr.ll

@@ -35,15 +35,15 @@ define arm_aapcscc void @irq_fn() alignstack(8) "interrupt"="IRQ" {
   ; Normal AAPCS function (r0-r3 pushed onto stack by hardware, lr set to
   ; appropriate sentinel so no special return needed).
 ; CHECK-M-LABEL: irq_fn:
-; CHECK-M: push.w {r4, r7, r11, lr}
-; CHECK-M: add.w r11, sp, #8
+; CHECK-M: push {r4, r6, r7, lr}
+; CHECK-M: add r7, sp, #8
 ; CHECK-M: mov r4, sp
 ; CHECK-M: bfc r4, #0, #3
 ; CHECK-M: mov sp, r4
 ; CHECK-M: bl _bar
-; CHECK-M: sub.w r4, r11, #8
+; CHECK-M: sub.w r4, r7, #8
 ; CHECK-M: mov sp, r4
-; CHECK-M: pop.w {r4, r7, r11, pc}
+; CHECK-M: pop {r4, r6, r7, pc}
 
   call arm_aapcscc void @bar()
   ret void

test/CodeGen/ARM/none-macho.ll

@@ -43,8 +43,8 @@ define i32 @test_frame_ptr() {
 ; CHECK-LABEL: test_frame_ptr:
   call void @test_trap()
 
-  ; Frame pointer is r11.
-; CHECK: mov r11, sp
+  ; Frame pointer is r7.
+; CHECK: mov r7, sp
   ret i32 42
 }
 
@@ -58,9 +58,11 @@ define void @test_two_areas(%big_arr* %addr) {
   ; This goes with the choice of r7 as FP (largely). FP and LR have to be stored
   ; consecutively on the stack for the frame record to be valid, which means we
   ; need the 2 register-save areas employed by iOS.
-; CHECK-NON-FAST: push.w {r4, r5, r6, r7, r8, r9, r10, r11, lr}
+; CHECK-NON-FAST: push {r4, r5, r6, r7, lr}
+; CHECK-NON-FAST: push.w {r8, r9, r10, r11}
 ; ...
-; CHECK-NON-FAST: pop.w {r4, r5, r6, r7, r8, r9, r10, r11, pc}
+; CHECK-NON-FAST: pop.w {r8, r9, r10, r11}
+; CHECK-NON-FAST: pop {r4, r5, r6, r7, pc}
   ret void
 }
 

test/CodeGen/Thumb2/emit-unwinding.ll

@@ -1,6 +1,6 @@
 ; RUN: llc -mtriple thumbv7em-apple-unknown-eabi-macho %s -o - -O0 | FileCheck %s
 
-; CHECK: add.w r11, sp, #{{[1-9]+}}
+; CHECK: add r7, sp, #{{[1-9]+}}
 
 define void @foo1() {
   call void asm sideeffect "", "~{r4}"()