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[SystemZ] Implement backchain attribute.

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This introduces a SystemZ-specific "backchain" attribute on function, which
enables writing the frame backchain link as specified by the ABI.  This will
be used to implement -mbackchain option in clang.

Differential Revision: http://reviews.llvm.org/D19889

llvm-svn: 268571
This commit is contained in:
Marcin Koscielnicki 2016-05-04 23:31:20 +00:00
parent 91bbed9888
commit 237ad4edbd
3 changed files with 130 additions and 4 deletions
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13
lib/Target/SystemZ/SystemZFrameLowering.cpp
View File

@ -354,6 +354,15 @@ void SystemZFrameLowering::emitPrologue(MachineFunction &MF,
uint64_t StackSize = getAllocatedStackSize(MF);
if (StackSize) {
// Determine if we want to store a backchain.
bool StoreBackchain = MF.getFunction()->hasFnAttribute("backchain");
// If we need backchain, save current stack pointer. R1 is free at this
// point.
if (StoreBackchain)
BuildMI(MBB, MBBI, DL, ZII->get(SystemZ::LGR))
.addReg(SystemZ::R1D).addReg(SystemZ::R15D);
// Allocate StackSize bytes.
int64_t Delta = -int64_t(StackSize);
emitIncrement(MBB, MBBI, DL, SystemZ::R15D, Delta, ZII);
@ -364,6 +373,10 @@ void SystemZFrameLowering::emitPrologue(MachineFunction &MF,
BuildMI(MBB, MBBI, DL, ZII->get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
SPOffsetFromCFA += Delta;
if (StoreBackchain)
BuildMI(MBB, MBBI, DL, ZII->get(SystemZ::STG))
.addReg(SystemZ::R1D).addReg(SystemZ::R15D).addImm(0).addReg(0);
}
if (HasFP) {

37
lib/Target/SystemZ/SystemZISelLowering.cpp
View File

@ -2835,8 +2835,9 @@ SDValue SystemZTargetLowering::lowerVACOPY(SDValue Op,
SDValue SystemZTargetLowering::
lowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const {
const TargetFrameLowering *TFI = Subtarget.getFrameLowering();
bool RealignOpt = !DAG.getMachineFunction().getFunction()->
hasFnAttribute("no-realign-stack");
MachineFunction &MF = DAG.getMachineFunction();
bool RealignOpt = !MF.getFunction()-> hasFnAttribute("no-realign-stack");
bool StoreBackchain = MF.getFunction()->hasFnAttribute("backchain");
SDValue Chain = Op.getOperand(0);
SDValue Size = Op.getOperand(1);
@ -2858,6 +2859,12 @@ lowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const {
// Get a reference to the stack pointer.
SDValue OldSP = DAG.getCopyFromReg(Chain, DL, SPReg, MVT::i64);
// If we need a backchain, save it now.
SDValue Backchain;
if (StoreBackchain)
Backchain = DAG.getLoad(MVT::i64, DL, Chain, OldSP, MachinePointerInfo(),
false, false, false, 0);
// Add extra space for alignment if needed.
if (ExtraAlignSpace)
NeededSpace = DAG.getNode(ISD::ADD, DL, MVT::i64, NeededSpace,
@ -2885,6 +2892,10 @@ lowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const {
DAG.getConstant(~(RequiredAlign - 1), DL, MVT::i64));
}
if (StoreBackchain)
Chain = DAG.getStore(Chain, DL, Backchain, NewSP, MachinePointerInfo(),
false, false, 0);
SDValue Ops[2] = { Result, Chain };
return DAG.getMergeValues(Ops, DL);
}
@ -3336,8 +3347,26 @@ SDValue SystemZTargetLowering::lowerSTACKRESTORE(SDValue Op,
SelectionDAG &DAG) const {
MachineFunction &MF = DAG.getMachineFunction();
MF.getInfo<SystemZMachineFunctionInfo>()->setManipulatesSP(true);
return DAG.getCopyToReg(Op.getOperand(0), SDLoc(Op),
SystemZ::R15D, Op.getOperand(1));
bool StoreBackchain = MF.getFunction()->hasFnAttribute("backchain");
SDValue Chain = Op.getOperand(0);
SDValue NewSP = Op.getOperand(1);
SDValue Backchain;
SDLoc DL(Op);
if (StoreBackchain) {
SDValue OldSP = DAG.getCopyFromReg(Chain, DL, SystemZ::R15D, MVT::i64);
Backchain = DAG.getLoad(MVT::i64, DL, Chain, OldSP, MachinePointerInfo(),
false, false, false, 0);
}
Chain = DAG.getCopyToReg(Chain, DL, SystemZ::R15D, NewSP);
if (StoreBackchain)
Chain = DAG.getStore(Chain, DL, Backchain, NewSP, MachinePointerInfo(),
false, false, 0);
return Chain;
}
SDValue SystemZTargetLowering::lowerPREFETCH(SDValue Op,

84
test/CodeGen/SystemZ/backchain.ll Normal file
View File

@ -0,0 +1,84 @@
; Test the backchain attribute.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
declare i8 *@llvm.stacksave()
declare void @llvm.stackrestore(i8 *)
declare void @g()
; nothing should happen if no stack frame is needed.
define void @f1() "backchain" {
; CHECK-LABEL: f1:
; CHECK-NOT: stg
ret void
}
; check that backchain is saved if we call someone
define void @f2() "backchain" {
; CHECK-LABEL: f2:
; CHECK: stmg %r14, %r15, 112(%r15)
; CHECK: lgr %r1, %r15
; CHECK: aghi %r15, -160
; CHECK: stg %r1, 0(%r15)
call void @g()
call void @g()
ret void
}
; check that backchain is saved if we have an alloca
define void @f3() "backchain" {
; CHECK-LABEL: f3:
; CHECK-NOT: stmg
; CHECK: lgr %r1, %r15
; CHECK: aghi %r15, -168
; CHECK: stg %r1, 0(%r15)
%ign = alloca i8, i32 4
ret void
}
; check that alloca copies the backchain
define void @f4(i32 %len) "backchain" {
; CHECK-LABEL: f4:
; CHECK: stmg %r11, %r15, 88(%r15)
; CHECK: lgr %r1, %r15
; CHECK: aghi %r15, -160
; CHECK: stg %r1, 0(%r15)
; CHECK: lgr %r11, %r15
; CHECK: lg [[BC:%r[0-9]+]], 0(%r15)
; CHECK: lgr [[NEWSP:%r[0-9]+]], %r15
; CHECK: lgr %r15, [[NEWSP]]
; CHECK: stg [[BC]], 0([[NEWSP]])
%ign = alloca i8, i32 %len
ret void
}
; check that llvm.stackrestore restores the backchain
define void @f5(i32 %count1, i32 %count2) "backchain" {
; CHECK-LABEL: f5:
; CHECK: stmg %r11, %r15, 88(%r15)
; CHECK: lgr %r1, %r15
; CHECK: aghi %r15, -160
; CHECK: stg %r1, 0(%r15)
; CHECK: lgr %r11, %r15
; CHECK: lgr [[SAVESP:%r[0-9]+]], %r15
; CHECK: lg [[BC:%r[0-9]+]], 0(%r15)
; CHECK: lgr [[NEWSP:%r[0-9]+]], %r15
; CHECK: lgr %r15, [[NEWSP]]
; CHECK: stg [[BC]], 0([[NEWSP]])
; CHECK: lg [[BC2:%r[0-9]+]], 0(%r15)
; CHECK: lgr %r15, [[SAVESP]]
; CHECK: stg [[BC2]], 0([[SAVESP]])
; CHECK: lg [[BC3:%r[0-9]+]], 0(%r15)
; CHECK: lgr [[NEWSP2:%r[0-9]+]], %r15
; CHECK: lgr %r15, [[NEWSP2]]
; CHECK: stg [[BC3]], 0([[NEWSP2]])
; CHECK: lmg %r11, %r15, 248(%r11)
; CHECK: br %r14
%src = call i8 *@llvm.stacksave()
%array1 = alloca i8, i32 %count1
store volatile i8 0, i8 *%array1
call void @llvm.stackrestore(i8 *%src)
%array2 = alloca i8, i32 %count2
store volatile i8 0, i8 *%array2
ret void
}