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[X86] add dwarf annotation for inline stack probe (#100)
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While probing stack, the stack register is moved without dwarf
information, which could cause panic if unwind the backtrace.
This commit only add annotation for the inline stack probe case.
Dwarf information for the loop case should be done in another
patch and need further discussion.

Reviewed By: nagisa

Differential Revision: https://reviews.llvm.org/D99579

Co-authored-by: YangKeao <keao.yang@yahoo.com>
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@nagisa @YangKeao @nikic
2 people authored and nikic committed Jul 10, 2021
1 parent c64b1fb commit c40829e
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Showing 6 changed files with 81 additions and 35 deletions.
26 changes: 23 additions & 3 deletions llvm/lib/Target/X86/X86FrameLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -553,6 +553,8 @@ void X86FrameLowering::emitStackProbeInlineGenericBlock(
MachineBasicBlock::iterator MBBI, const DebugLoc &DL, uint64_t Offset,
uint64_t AlignOffset) const {

const bool NeedsDwarfCFI = needsDwarfCFI(MF);
const bool HasFP = hasFP(MF);
const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
const X86TargetLowering &TLI = *STI.getTargetLowering();
const unsigned Opc = getSUBriOpcode(Uses64BitFramePtr, Offset);
Expand All @@ -570,6 +572,11 @@ void X86FrameLowering::emitStackProbeInlineGenericBlock(
.addReg(StackPtr)
.addImm(StackProbeSize - AlignOffset)
.setMIFlag(MachineInstr::FrameSetup);
if (!HasFP && NeedsDwarfCFI) {
BuildCFI(MBB, MBBI, DL,
MCCFIInstruction::createAdjustCfaOffset(
nullptr, StackProbeSize - AlignOffset));
}
MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.

addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(MovMIOpc))
Expand All @@ -591,7 +598,11 @@ void X86FrameLowering::emitStackProbeInlineGenericBlock(
.setMIFlag(MachineInstr::FrameSetup);
MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.


if (!HasFP && NeedsDwarfCFI) {
BuildCFI(
MBB, MBBI, DL,
MCCFIInstruction::createAdjustCfaOffset(nullptr, StackProbeSize));
}
addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(MovMIOpc))
.setMIFlag(MachineInstr::FrameSetup),
StackPtr, false, 0)
Expand All @@ -607,6 +618,8 @@ void X86FrameLowering::emitStackProbeInlineGenericBlock(
.addReg(StackPtr)
.addImm(ChunkSize)
.setMIFlag(MachineInstr::FrameSetup);
// No need to adjust Dwarf CFA offset here, the last position of the stack has
// been defined
MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
}

Expand Down Expand Up @@ -1200,6 +1213,13 @@ bool X86FrameLowering::has128ByteRedZone(const MachineFunction& MF) const {
return Is64Bit && !IsWin64CC && !Fn.hasFnAttribute(Attribute::NoRedZone);
}

bool X86FrameLowering::isWin64Prologue(const MachineFunction &MF) const {
return MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
}

bool X86FrameLowering::needsDwarfCFI(const MachineFunction &MF) const {
return !isWin64Prologue(MF) && MF.needsFrameMoves();
}

/// emitPrologue - Push callee-saved registers onto the stack, which
/// automatically adjust the stack pointer. Adjust the stack pointer to allocate
Expand Down Expand Up @@ -1305,13 +1325,13 @@ void X86FrameLowering::emitPrologue(MachineFunction &MF,
MF.hasEHFunclets() && Personality == EHPersonality::CoreCLR;
bool IsClrFunclet = IsFunclet && FnHasClrFunclet;
bool HasFP = hasFP(MF);
bool IsWin64Prologue = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
bool IsWin64Prologue = isWin64Prologue(MF);
bool NeedsWin64CFI = IsWin64Prologue && Fn.needsUnwindTableEntry();
// FIXME: Emit FPO data for EH funclets.
bool NeedsWinFPO =
!IsFunclet && STI.isTargetWin32() && MMI.getModule()->getCodeViewFlag();
bool NeedsWinCFI = NeedsWin64CFI || NeedsWinFPO;
bool NeedsDwarfCFI = !IsWin64Prologue && MF.needsFrameMoves();
bool NeedsDwarfCFI = needsDwarfCFI(MF);
Register FramePtr = TRI->getFrameRegister(MF);
const Register MachineFramePtr =
STI.isTarget64BitILP32()
Expand Down
4 changes: 4 additions & 0 deletions llvm/lib/Target/X86/X86FrameLowering.h
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Original file line number Diff line number Diff line change
Expand Up @@ -192,6 +192,10 @@ class X86FrameLowering : public TargetFrameLowering {
bool has128ByteRedZone(const MachineFunction& MF) const;

private:
bool isWin64Prologue(const MachineFunction &MF) const;

bool needsDwarfCFI(const MachineFunction &MF) const;

uint64_t calculateMaxStackAlign(const MachineFunction &MF) const;

/// Emit target stack probe as a call to a helper function
Expand Down
1 change: 1 addition & 0 deletions llvm/test/CodeGen/X86/stack-clash-medium-natural-probes-mutliple-objects.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -8,6 +8,7 @@ define i32 @foo() local_unnamed_addr #0 {
; CHECK-LABEL: foo:
; CHECK: # %bb.0:
; CHECK-NEXT: subq $4096, %rsp # imm = 0x1000
; CHECK-NEXT: .cfi_adjust_cfa_offset 4096
; CHECK-NEXT: movq $0, (%rsp)
; CHECK-NEXT: subq $1784, %rsp # imm = 0x6F8
; CHECK-NEXT: .cfi_def_cfa_offset 5888
Expand Down
26 changes: 12 additions & 14 deletions llvm/test/CodeGen/X86/stack-clash-medium-natural-probes.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -7,20 +7,18 @@ target triple = "x86_64-unknown-linux-gnu"
define i32 @foo() local_unnamed_addr #0 {

; CHECK-LABEL: foo:
; CHECK: # %bb.0:
; CHECK-NEXT: subq $4096, %rsp # imm = 0x1000
; CHECK-NEXT: movq $0, (%rsp)
; CHECK-NEXT: subq $3784, %rsp # imm = 0xEC8
; CHECK-NEXT: .cfi_def_cfa_offset 7888
; CHECK-NEXT: movl $1, 264(%rsp)
; CHECK-NEXT: movl $1, 4664(%rsp)
; CHECK-NEXT: movl -128(%rsp), %eax
; CHECK-NEXT: addq $7880, %rsp # imm = 0x1EC8
; CHECK-NEXT: .cfi_def_cfa_offset 8
; CHECK-NEXT: retq



; CHECK: # %bb.0:
; CHECK-NEXT: subq $4096, %rsp # imm = 0x1000
; CHECK-NEXT: .cfi_adjust_cfa_offset 4096
; CHECK-NEXT: movq $0, (%rsp)
; CHECK-NEXT: subq $3784, %rsp # imm = 0xEC8
; CHECK-NEXT: .cfi_def_cfa_offset 7888
; CHECK-NEXT: movl $1, 264(%rsp)
; CHECK-NEXT: movl $1, 4664(%rsp)
; CHECK-NEXT: movl -128(%rsp), %eax
; CHECK-NEXT: addq $7880, %rsp # imm = 0x1EC8
; CHECK-NEXT: .cfi_def_cfa_offset 8
; CHECK-NEXT: retq
%a = alloca i32, i64 2000, align 16
%b0 = getelementptr inbounds i32, i32* %a, i64 98
%b1 = getelementptr inbounds i32, i32* %a, i64 1198
Expand Down
29 changes: 27 additions & 2 deletions llvm/test/CodeGen/X86/stack-clash-medium.ll
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Original file line number Diff line number Diff line change
@@ -1,7 +1,32 @@
; RUN: llc -mtriple=x86_64-linux-android < %s | FileCheck -check-prefix=CHECK-X86-64 %s
; RUN: llc -mtriple=i686-linux-android < %s | FileCheck -check-prefix=CHECK-X86-32 %s
; RUN: llc -mtriple=x86_64-linux-android < %s | FileCheck -check-prefix=CHECK-X86-64 %s
; RUN: llc -mtriple=i686-linux-android < %s | FileCheck -check-prefix=CHECK-X86-32 %s

define i32 @foo() local_unnamed_addr #0 {
; CHECK-X86-64-LABEL: foo:
; CHECK-X86-64: # %bb.0:
; CHECK-X86-64-NEXT: subq $4096, %rsp # imm = 0x1000
; CHECK-X86-64-NEXT: .cfi_adjust_cfa_offset 4096
; CHECK-X86-64-NEXT: movq $0, (%rsp)
; CHECK-X86-64-NEXT: subq $3784, %rsp # imm = 0xEC8
; CHECK-X86-64-NEXT: .cfi_def_cfa_offset 7888
; CHECK-X86-64-NEXT: movl $1, 672(%rsp)
; CHECK-X86-64-NEXT: movl -128(%rsp), %eax
; CHECK-X86-64-NEXT: addq $7880, %rsp # imm = 0x1EC8
; CHECK-X86-64-NEXT: .cfi_def_cfa_offset 8
; CHECK-X86-64-NEXT: retq
;
; CHECK-X86-32-LABEL: foo:
; CHECK-X86-32: # %bb.0:
; CHECK-X86-32-NEXT: subl $4096, %esp # imm = 0x1000
; CHECK-X86-32-NEXT: .cfi_adjust_cfa_offset 4096
; CHECK-X86-32-NEXT: movl $0, (%esp)
; CHECK-X86-32-NEXT: subl $3916, %esp # imm = 0xF4C
; CHECK-X86-32-NEXT: .cfi_def_cfa_offset 8016
; CHECK-X86-32-NEXT: movl $1, 800(%esp)
; CHECK-X86-32-NEXT: movl (%esp), %eax
; CHECK-X86-32-NEXT: addl $8012, %esp # imm = 0x1F4C
; CHECK-X86-32-NEXT: .cfi_def_cfa_offset 4
; CHECK-X86-32-NEXT: retl
%a = alloca i32, i64 2000, align 16
%b = getelementptr inbounds i32, i32* %a, i64 200
store volatile i32 1, i32* %b
Expand Down
30 changes: 14 additions & 16 deletions llvm/test/CodeGen/X86/stack-clash-unknown-call.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -7,22 +7,20 @@ target triple = "x86_64-unknown-linux-gnu"
declare void @llvm.memset.p0i8.i64(i8* nocapture writeonly, i8, i64, i1 immarg);

define void @foo() local_unnamed_addr #0 {

;CHECK-LABEL: foo:
;CHECK: # %bb.0:
;CHECK-NEXT: subq $4096, %rsp # imm = 0x1000
; it's important that we don't use the call as a probe here
;CHECK-NEXT: movq $0, (%rsp)
;CHECK-NEXT: subq $3912, %rsp # imm = 0xF48
;CHECK-NEXT: .cfi_def_cfa_offset 8016
;CHECK-NEXT: movq %rsp, %rdi
;CHECK-NEXT: movl $8000, %edx # imm = 0x1F40
;CHECK-NEXT: xorl %esi, %esi
;CHECK-NEXT: callq memset
;CHECK-NEXT: addq $8008, %rsp # imm = 0x1F48
;CHECK-NEXT: .cfi_def_cfa_offset 8
;CHECK-NEXT: retq

; CHECK-LABEL: foo:
; CHECK: # %bb.0:
; CHECK-NEXT: subq $4096, %rsp # imm = 0x1000
; CHECK-NEXT: .cfi_adjust_cfa_offset 4096
; CHECK-NEXT: movq $0, (%rsp)
; CHECK-NEXT: subq $3912, %rsp # imm = 0xF48
; CHECK-NEXT: .cfi_def_cfa_offset 8016
; CHECK-NEXT: movq %rsp, %rdi
; CHECK-NEXT: movl $8000, %edx # imm = 0x1F40
; CHECK-NEXT: xorl %esi, %esi
; CHECK-NEXT: callq memset@PLT
; CHECK-NEXT: addq $8008, %rsp # imm = 0x1F48
; CHECK-NEXT: .cfi_def_cfa_offset 8
; CHECK-NEXT: retq
%a = alloca i8, i64 8000, align 16
call void @llvm.memset.p0i8.i64(i8* align 16 %a, i8 0, i64 8000, i1 false)
ret void
Expand Down

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