Commit 27021b8a authored by Hans Wennborg's avatar Hans Wennborg
Browse files

Merging r323643: 

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r323643 | jdevlieghere | 2018-01-29 13:10:32 +0100 (Mon, 29 Jan 2018) | 16 lines

[Sparc] Account for bias in stack readjustment

Summary: This was broken long ago in D12208, which failed to account for
the fact that 64-bit SPARC uses a stack bias of 2047, and it is the
*unbiased* value which should be aligned, not the biased one. This was
seen to be an issue with Rust.

Patch by: jrtc27 (James Clarke)

Reviewers: jyknight, venkatra

Reviewed By: jyknight

Subscribers: jacob_hansen, JDevlieghere, fhahn, fedor.sergeev, llvm-commits

Differential Revision: https://reviews.llvm.org/D39425
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llvm-svn: 324090
parent 3b724f63

llvm/lib/Target/Sparc/SparcFrameLowering.cpp

+24 −5
Original line number Diff line number Diff line
@@ -88,10 +88,11 @@ void SparcFrameLowering::emitPrologue(MachineFunction &MF, 


  assert(&MF.front() == &MBB && "Shrink-wrapping not yet supported");

  MachineFrameInfo &MFI = MF.getFrameInfo();

  const SparcSubtarget &Subtarget = MF.getSubtarget<SparcSubtarget>();

  const SparcInstrInfo &TII =

      *static_cast<const SparcInstrInfo *>(MF.getSubtarget().getInstrInfo());

      *static_cast<const SparcInstrInfo *>(Subtarget.getInstrInfo());

  const SparcRegisterInfo &RegInfo =

      *static_cast<const SparcRegisterInfo *>(MF.getSubtarget().getRegisterInfo());

      *static_cast<const SparcRegisterInfo *>(Subtarget.getRegisterInfo());

  MachineBasicBlock::iterator MBBI = MBB.begin();

  // Debug location must be unknown since the first debug location is used

  // to determine the end of the prologue.
@@ -141,7 +142,7 @@ void SparcFrameLowering::emitPrologue(MachineFunction &MF, 


  // Adds the SPARC subtarget-specific spill area to the stack

  // size. Also ensures target-required alignment.

  NumBytes = MF.getSubtarget<SparcSubtarget>().getAdjustedFrameSize(NumBytes);

  NumBytes = Subtarget.getAdjustedFrameSize(NumBytes);



  // Finally, ensure that the size is sufficiently aligned for the

  // data on the stack.
@@ -176,9 +177,27 @@ void SparcFrameLowering::emitPrologue(MachineFunction &MF, 
      .addCFIIndex(CFIIndex);



  if (NeedsStackRealignment) {

    // andn %o6, MaxAlign-1, %o6

    int64_t Bias = Subtarget.getStackPointerBias();

    unsigned regUnbiased;

    if (Bias) {

      // This clobbers G1 which we always know is available here.

      regUnbiased = SP::G1;

      // add %o6, BIAS, %g1

      BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), regUnbiased)

        .addReg(SP::O6).addImm(Bias);

    } else

      regUnbiased = SP::O6;



    // andn %regUnbiased, MaxAlign-1, %regUnbiased

    int MaxAlign = MFI.getMaxAlignment();

    BuildMI(MBB, MBBI, dl, TII.get(SP::ANDNri), SP::O6).addReg(SP::O6).addImm(MaxAlign - 1);

    BuildMI(MBB, MBBI, dl, TII.get(SP::ANDNri), regUnbiased)

      .addReg(regUnbiased).addImm(MaxAlign - 1);



    if (Bias) {

      // add %g1, -BIAS, %o6

      BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), SP::O6)

        .addReg(regUnbiased).addImm(-Bias);

    }

  }

}

llvm/test/CodeGen/SPARC/stack-align.ll

+11 −5
Original line number Diff line number Diff line 
; RUN: llc -march=sparc < %s | FileCheck %s

; RUN: llc -march=sparc < %s | FileCheck %s --check-prefixes=CHECK,CHECK32

; RUN: llc -march=sparcv9 < %s | FileCheck %s --check-prefixes=CHECK,CHECK64

declare void @stack_realign_helper(i32 %a, i32* %b)



;; This is a function where we have a local variable of 64-byte
@@ -7,10 +8,15 @@ declare void @stack_realign_helper(i32 %a, i32* %b) 
;; the argument is accessed via frame pointer not stack pointer (to %o0).



;; CHECK-LABEL: stack_realign:

;; CHECK:      andn %sp, 63, %sp

;; CHECK-NEXT: ld [%fp+92], %o0

;; CHECK32:      andn %sp, 63, %sp

;; CHECK32-NEXT: ld [%fp+92], %o0

;; CHECK64:      add %sp, 2047, %g1

;; CHECK64-NEXT: andn %g1, 63, %g1

;; CHECK64-NEXT: add %g1, -2047, %sp

;; CHECK64-NEXT: ld [%fp+2227], %o0

;; CHECK-NEXT:   call stack_realign_helper

;; CHECK-NEXT: add %sp, 128, %o1

;; CHECK32-NEXT: add %sp, 128, %o1

;; CHECK64-NEXT: add %sp, 2239, %o1



define void @stack_realign(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f, i32 %g) {

entry: