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[Sparc] Account for bias in stack readjustment #94

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Jan 29, 2018
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[Sparc] Account for bias in stack readjustment #94

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29 changes: 24 additions & 5 deletions lib/Target/Sparc/SparcFrameLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -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.
Expand Down Expand Up @@ -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.
Expand Down Expand Up @@ -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 %o6, -BIAS, %g1
BuildMI(MBB, MBBI, dl, TII.get(SP::ADDri), SP::O6)
.addReg(regUnbiased).addImm(-Bias);
}
}
}

Expand Down
16 changes: 11 additions & 5 deletions test/CodeGen/SPARC/stack-align.ll
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Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
; 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
Expand All @@ -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
;; CHECK-NEXT: call stack_realign_helper
;; CHECK-NEXT: add %sp, 128, %o1
;; 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
;; 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:
Expand Down