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Handle CET for -exception-model sjlj
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Summary:
In SjLj exception mode, the old landingpad BB will create a new landingpad BB and use indirect branch jump to the old landingpad BB in lowering.
So we should add 2 endbr for this exception model.

Reviewers: hjl.tools, craig.topper, annita.zhang, LuoYuanke, pengfei, efriedma

Reviewed By: LuoYuanke

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D77124
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@xiangzh1
xiangzh1 committed Apr 20, 2020
1 parent edcfc39 commit 0980038
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Showing 3 changed files with 244 additions and 11 deletions.
33 changes: 27 additions & 6 deletions llvm/lib/Target/X86/X86IndirectBranchTracking.cpp
View file
Expand Up @@ -138,17 +138,38 @@ bool X86IndirectBranchTrackingPass::runOnMachineFunction(MachineFunction &MF) {
if (MBB.hasAddressTaken())
Changed |= addENDBR(MBB, MBB.begin());

// Exception handle may indirectly jump to catch pad, So we should add
// ENDBR before catch pad instructions.
bool EHPadIBTNeeded = MBB.isEHPad();

for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
if (I->isCall() && IsCallReturnTwice(I->getOperand(0)))
Changed |= addENDBR(MBB, std::next(I));
}

if (EHPadIBTNeeded && I->isEHLabel()) {
// Exception handle may indirectly jump to catch pad, So we should add
// ENDBR before catch pad instructions. For SjLj exception model, it will
// create a new BB(new landingpad) indirectly jump to the old landingpad.
if (TM->Options.ExceptionModel == ExceptionHandling::SjLj) {
for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
// New Landingpad BB without EHLabel.
if (MBB.isEHPad()) {
if (I->isDebugInstr())
continue;
Changed |= addENDBR(MBB, I);
break;
} else if (I->isEHLabel()) {
// Old Landingpad BB (is not Landingpad now) with
// the the old "callee" EHLabel.
MCSymbol *Sym = I->getOperand(0).getMCSymbol();
if (!MF.hasCallSiteLandingPad(Sym))
continue;
Changed |= addENDBR(MBB, std::next(I));
break;
}
}
} else if (MBB.isEHPad()){
for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I) {
if (!I->isEHLabel())
continue;
Changed |= addENDBR(MBB, std::next(I));
EHPadIBTNeeded = false;
break;
}
}
}
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73 changes: 68 additions & 5 deletions llvm/test/CodeGen/X86/indirect-branch-tracking-eh.ll
View file
@@ -1,15 +1,78 @@
; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s
; RUN: llc -mtriple=i386-unknown-unknown < %s | FileCheck %s
; RUN: llc -mtriple=x86_64-unknown-unknown < %s | FileCheck %s --check-prefix=X86_64
; RUN: llc -mtriple=i386-unknown-unknown < %s | FileCheck %s --check-prefix=X86
; RUN: llc -mtriple i386-windows-gnu -exception-model sjlj -verify-machineinstrs=0 < %s | FileCheck %s --check-prefix=SJLJ
; RUN: llc -mtriple i386-windows-gnu -exception-model sjlj -verify-machineinstrs=0 < %s | FileCheck %s --check-prefix=NUM

; X86_64: test_eh: # @test_eh
; X86_64-NEXT: .Lfunc_begin0:
; X86_64: # %bb.0: # %entry
; X86_64-NEXT: endbr64
; X86_64-NEXT: pushq %rax
; X86_64: .Ltmp0:
; X86_64-NEXT: callq _Z20function_that_throwsv
; X86_64-NEXT: .Ltmp1:
; X86_64-NEXT: # %bb.1: # %try.cont
; X86_64: retq
; X86_64-NEXT: .LBB0_2: # %lpad
; X86_64-NEXT: .cfi_def_cfa_offset 16
; X86_64-NEXT: .Ltmp2:
; X86_64-NEXT: endbr64
; X86_64: callq __cxa_begin_catch


; X86: test_eh: # @test_eh
; X86-NEXT: .Lfunc_begin0:
; X86: # %bb.0: # %entry
; X86-NEXT: endbr32
; X86-NEXT: .Ltmp0:
; X86: calll _Z20function_that_throwsv
; X86-NEXT: .Ltmp1:
; X86-NEXT: # %bb.1: # %try.cont
; X86-NEXT: retl
; X86-NEXT: .LBB0_2: # %lpad
; X86-NEXT: .Ltmp2:
; X86-NEXT: endbr32
; X86: calll __cxa_begin_catch

; NUM-COUNT-3: endbr32

; SJLJ: test_eh:
; SJLJ-NEXT: Lfunc_begin0:
; SJLJ-NEXT: # %bb.0: # %entry
; SJLJ-NEXT: endbr32
; SJLJ: calll __Unwind_SjLj_Register
; SJLJ: Ltmp0:
; SJLJ: calll __Z20function_that_throwsv
; SJLJ: LBB0_2: # %try.cont
; SJLJ: calll __Unwind_SjLj_Unregister
; SJLJ: retl

; SJLJ: LBB0_3:
; SJLJ-NEXT: endbr32
; SJLJ-NEXT: leal
; SJLJ-NEXT: movl
; SJLJ-NEXT: cmpl
; SJLJ-NEXT: jb LBB0_4

; SJLJ: LBB0_4:
; SJLJ-NEXT: jmpl *LJTI0_0(,%eax,4)

; SJLJ: LBB0_6: # %lpad
; SJLJ-NEXT: Ltmp2:
; SJLJ-NEXT: endbr32
; SJLJ: calll ___cxa_begin_catch
; SJLJ: jmp LBB0_2
; SJLJ: LJTI0_0:
; SJLJ-NEXT: .long LBB0_6


;There should be 2 endbr* instruction at entry and catch pad.
;CHECK-COUNT-2: endbr

declare void @_Z20function_that_throwsv()
declare i32 @__gxx_personality_sj0(...)
declare i8* @__cxa_begin_catch(i8*)
declare void @__cxa_end_catch()

define void @test8() personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
define void @test_eh() personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
entry:
invoke void @_Z20function_that_throwsv()
to label %try.cont unwind label %lpad
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149 changes: 149 additions & 0 deletions llvm/test/CodeGen/X86/indirect-branch-tracking-eh2.ll
View file
@@ -0,0 +1,149 @@
; RUN: llc -mtriple x86_64-unknown-unknown -exception-model sjlj -verify-machineinstrs=0 < %s | FileCheck %s --check-prefix=NUM
; RUN: llc -mtriple x86_64-unknown-unknown -exception-model sjlj -verify-machineinstrs=0 < %s | FileCheck %s --check-prefix=SJLJ

; NUM-COUNT-3: endbr64

;SJLJ: main: # @main
;SJLJ-NEXT: .Lmain$local:
;SJLJ-NEXT: .Lfunc_begin0:
;SJLJ-NEXT: # %bb.0: # %entry
;SJLJ-NEXT: endbr64
;SJLJ-NEXT: pushq %rbp
;SJLJ: callq _Unwind_SjLj_Register
;SJLJ-NEXT: .Ltmp0:
;SJLJ-NEXT: callq _Z3foov
;SJLJ-NEXT: .Ltmp1:
;SJLJ-NEXT: # %bb.1: # %invoke.cont
;SJLJ-NEXT: movl
;SJLJ-NEXT: .LBB0_7: # %return
;SJLJ: callq _Unwind_SjLj_Unregister
;SJLJ: retq
;SJLJ-NEXT: .LBB0_9:
;SJLJ-NEXT: endbr64
;SJLJ-NEXT: movl
;SJLJ-NEXT: cmpl
;SJLJ-NEXT: jb .LBB0_10
;SJLJ-NEXT: # %bb.11:
;SJLJ-NEXT: ud2
;SJLJ-NEXT: .LBB0_10:
;SJLJ-NEXT: leaq .LJTI0_0(%rip), %rcx
;SJLJ-NEXT: jmpq *(%rcx,%rax,8)
;SJLJ-NEXT: .LBB0_2: # %lpad
;SJLJ-NEXT: .Ltmp2:
;SJLJ-NEXT: endbr64
;SJLJ: jne .LBB0_4
;SJLJ-NEXT: # %bb.3: # %catch3
;SJLJ: callq __cxa_begin_catch
;SJLJ: jmp .LBB0_6
;SJLJ-NEXT: .LBB0_4: # %catch.fallthrough
;SJLJ-NEXT: cmpl
;SJLJ-NEXT: jne .LBB0_8
;SJLJ-NEXT: # %bb.5: # %catch
;SJLJ: callq __cxa_begin_catch
;SJLJ: cmpb
;SJLJ-NEXT: .LBB0_6: # %return
;SJLJ: callq __cxa_end_catch
;SJLJ-NEXT: jmp .LBB0_7
;SJLJ-NEXT: .LBB0_8: # %eh.resume
;SJLJ-NEXT: movl
;SJLJ-NEXT: .Lfunc_end0:
;SJLJ: .LJTI0_0:
;SJLJ-NEXT: .quad .LBB0_2

@_ZTIi = external dso_local constant i8*
@_ZTIc = external dso_local constant i8*

; Function Attrs: noinline norecurse optnone uwtable
define dso_local i32 @main() #0 personality i8* bitcast (i32 (...)* @__gxx_personality_sj0 to i8*) {
entry:
%retval = alloca i32, align 4
%exn.slot = alloca i8*
%ehselector.slot = alloca i32
%x = alloca i8, align 1
%x4 = alloca i32, align 4
store i32 0, i32* %retval, align 4
invoke void @_Z3foov()
to label %invoke.cont unwind label %lpad

invoke.cont: ; preds = %entry
br label %try.cont

lpad: ; preds = %entry
%0 = landingpad { i8*, i32 }
catch i8* bitcast (i8** @_ZTIi to i8*)
catch i8* bitcast (i8** @_ZTIc to i8*)
%1 = extractvalue { i8*, i32 } %0, 0
store i8* %1, i8** %exn.slot, align 8
%2 = extractvalue { i8*, i32 } %0, 1
store i32 %2, i32* %ehselector.slot, align 4
br label %catch.dispatch

catch.dispatch: ; preds = %lpad
%sel = load i32, i32* %ehselector.slot, align 4
%3 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*)) #3
%matches = icmp eq i32 %sel, %3
br i1 %matches, label %catch3, label %catch.fallthrough

catch3: ; preds = %catch.dispatch
%exn5 = load i8*, i8** %exn.slot, align 8
%4 = call i8* @__cxa_begin_catch(i8* %exn5) #3
%5 = bitcast i8* %4 to i32*
%6 = load i32, i32* %5, align 4
store i32 %6, i32* %x4, align 4
%7 = load i32, i32* %x4, align 4
%cmp6 = icmp ne i32 %7, 5
%conv7 = zext i1 %cmp6 to i32
store i32 %conv7, i32* %retval, align 4
call void @__cxa_end_catch() #3
br label %return

catch.fallthrough: ; preds = %catch.dispatch
%8 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIc to i8*)) #3
%matches1 = icmp eq i32 %sel, %8
br i1 %matches1, label %catch, label %eh.resume

catch: ; preds = %catch.fallthrough
%exn = load i8*, i8** %exn.slot, align 8
%9 = call i8* @__cxa_begin_catch(i8* %exn) #3
%10 = load i8, i8* %9, align 1
store i8 %10, i8* %x, align 1
%11 = load i8, i8* %x, align 1
%conv = sext i8 %11 to i32
%cmp = icmp ne i32 %conv, 3
%conv2 = zext i1 %cmp to i32
store i32 %conv2, i32* %retval, align 4
call void @__cxa_end_catch() #3
br label %return

try.cont: ; preds = %invoke.cont
store i32 1, i32* %retval, align 4
br label %return

return: ; preds = %try.cont, %catch3, %catch
%12 = load i32, i32* %retval, align 4
ret i32 %12

eh.resume: ; preds = %catch.fallthrough
%exn8 = load i8*, i8** %exn.slot, align 8
%sel9 = load i32, i32* %ehselector.slot, align 4
%lpad.val = insertvalue { i8*, i32 } undef, i8* %exn8, 0
%lpad.val10 = insertvalue { i8*, i32 } %lpad.val, i32 %sel9, 1
resume { i8*, i32 } %lpad.val10
}

declare dso_local void @_Z3foov() #1

declare dso_local i32 @__gxx_personality_sj0(...)

; Function Attrs: nounwind readnone
declare i32 @llvm.eh.typeid.for(i8*) #2

declare dso_local i8* @__cxa_begin_catch(i8*)

declare dso_local void @__cxa_end_catch()

!llvm.module.flags = !{!0, !1, !2}

!0 = !{i32 1, !"wchar_size", i32 4}
!1 = !{i32 4, !"cf-protection-return", i32 1}
!2 = !{i32 4, !"cf-protection-branch", i32 1}

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