forked from OSchip/llvm-project
[BOLT] Fix ignored LP at fragment start
If the first block of a fragment is also a landing pad, the landing pad is not used if an exception is thrown. This is because the landing pad is at the same start address that the corresponding LSDA describes. In that case, the offset in the call site records to refer to that landing pad is zero, and a zero offset is interpreted by the personality function as "no handler" and ignored. Reviewed By: Amir Differential Revision: https://reviews.llvm.org/D132053
This commit is contained in:
Fabian Parzefall
parent
4ddc9c8e12
commit
fd159c2316
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@ -400,6 +400,17 @@ void BinaryEmitter::emitFunctionBody(BinaryFunction &BF, bool EmitColdPart,
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const FunctionFragment FF = BF.getLayout().getFragment(
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EmitColdPart ? FragmentNum::cold() : FragmentNum::hot());
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if (!FF.empty() && FF.front()->isLandingPad()) {
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assert(!FF.front()->isEntryPoint() &&
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"Landing pad cannot be entry point of function");
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// If the first block of the fragment is a landing pad, it's offset from the
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// start of the area that the corresponding LSDA describes is zero. In this
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// case, the call site entries in that LSDA have 0 as offset to the landing
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// pad, which the runtime interprets as "no handler". To prevent this,
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// insert some padding.
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Streamer.emitIntValue(BC.MIB->getTrapFillValue(), 1);
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}
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// Track the first emitted instruction with debug info.
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bool FirstInstr = true;
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for (BinaryBasicBlock *const BB : FF) {
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@ -0,0 +1,167 @@
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# Test that landing pads at fragment entries are not omitted during unwinding.
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# This uses profile2 splitting with a fake fdata, so SplitFunctions splits main
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# right before landing pad.
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# RUN: llvm-mc --filetype=obj --triple x86_64-unknown-unknown %s -o %t.o
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# RUN: link_fdata %s %t.o %t.fdata
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# RUN: llvm-strip --strip-unneeded %t.o
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# RUN: %clang++ %cflags %t.o -o %t.exe -Wl,-q
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# RUN: llvm-bolt %t.exe -o %t.bolt --split-functions --data=%t.fdata \
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# RUN: --print-split --print-only=main --split-eh --split-all-cold \
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# RUN: 2>&1 | FileCheck --check-prefix=BOLT-CHECK %s
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# RUN: %t.bolt | FileCheck --check-prefix=RUN-CHECK %s
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# BOLT-CHECK: ------- HOT-COLD SPLIT POINT -------
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# BOLT-CHECK-EMPTY:
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# BOLT-CHECK-NEXT: .LLP1
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# RUN-CHECK: failed successfully
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.text
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.file "lp-fragment-start.cpp"
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.globl main # -- Begin function main
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.p2align 4, 0x90
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.type main,@function
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main: # @main
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.Lfunc_begin0:
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.cfi_startproc
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.cfi_personality 155, DW.ref.__gxx_personality_v0
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.cfi_lsda 27, .Lexception0
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pushq %r15
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.cfi_def_cfa_offset 16
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pushq %r14
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.cfi_def_cfa_offset 24
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pushq %rbx
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.cfi_def_cfa_offset 32
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.cfi_offset %rbx, -32
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.cfi_offset %r14, -24
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.cfi_offset %r15, -16
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movl $16, %edi
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LL_fdata0:
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callq __cxa_allocate_exception@PLT
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# FDATA: 1 main #LL_fdata0# 1 __cxa_allocate_exception@PLT 0 0 1
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movq %rax, %rbx
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.Ltmp0:
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leaq .L.str(%rip), %rsi
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movq %rax, %rdi
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callq _ZNSt13runtime_errorC1EPKc@PLT
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jmp .Ltmp3
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.Ltmp1:
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# Cause split here, so .Ltmp5 is the first block of the fragment
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.Ltmp5: # LP for .Ltmp3 to .Ltmp4
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movq %rdx, %r15
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movq %rax, %r14
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jmp .LBB0_4
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.Ltmp3: # throw std::runtime_error
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movq _ZTISt13runtime_error@GOTPCREL(%rip), %rsi
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movq _ZNSt13runtime_errorD1Ev@GOTPCREL(%rip), %rdx
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movq %rbx, %rdi
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callq __cxa_throw@PLT # LP: .Ltmp5
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.Ltmp4:
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.Ltmp2:
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movq %rdx, %r15
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movq %rax, %r14
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movq %rbx, %rdi
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callq __cxa_free_exception@PLT
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.LBB0_4:
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movq %r14, %rdi
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cmpl $1, %r15d
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jne .LBB0_5
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callq __cxa_begin_catch@PLT
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movq (%rax), %rcx
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movq %rax, %rdi
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callq *16(%rcx)
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movq %rax, %rdi
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callq puts@PLT
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callq __cxa_end_catch@PLT
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xorl %eax, %eax
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popq %rbx
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.cfi_def_cfa_offset 24
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popq %r14
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.cfi_def_cfa_offset 16
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popq %r15
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.cfi_def_cfa_offset 8
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retq
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.LBB0_5:
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.cfi_def_cfa_offset 32
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callq _Unwind_Resume@PLT
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.Lfunc_end0:
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.size main, .Lfunc_end0-main
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.cfi_endproc
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.section .gcc_except_table,"a",@progbits
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.p2align 2
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GCC_except_table0:
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.Lexception0:
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.byte 255 # @LPStart Encoding = omit
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.byte 155 # @TType Encoding = indirect pcrel sdata4
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.uleb128 .Lttbase0-.Lttbaseref0
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.Lttbaseref0:
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.byte 1 # Call site Encoding = uleb128
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.uleb128 .Lcst_end0-.Lcst_begin0
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.Lcst_begin0:
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.uleb128 .Lfunc_begin0-.Lfunc_begin0 # >> Call Site 1 <<
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.uleb128 .Ltmp0-.Lfunc_begin0 # Call between .Lfunc_begin0 and .Ltmp0
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.byte 0 # has no landing pad
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.byte 0 # On action: cleanup
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.uleb128 .Ltmp0-.Lfunc_begin0 # >> Call Site 2 <<
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.uleb128 .Ltmp1-.Ltmp0 # Call between .Ltmp0 and .Ltmp1
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.uleb128 .Ltmp2-.Lfunc_begin0 # jumps to .Ltmp2
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.byte 3 # On action: 2
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.uleb128 .Ltmp3-.Lfunc_begin0 # >> Call Site 3 <<
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.uleb128 .Ltmp4-.Ltmp3 # Call between .Ltmp3 and .Ltmp4
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.uleb128 .Ltmp5-.Lfunc_begin0 # jumps to .Ltmp5
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.byte 5 # On action: 3
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.uleb128 .Ltmp4-.Lfunc_begin0 # >> Call Site 4 <<
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.uleb128 .Lfunc_end0-.Ltmp4 # Call between .Ltmp4 and .Lfunc_end0
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.byte 0 # has no landing pad
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.byte 0 # On action: cleanup
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.Lcst_end0:
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.byte 0 # >> Action Record 1 <<
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.byte 0 # No further actions
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.byte 1 # >> Action Record 2 <<
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.byte 125 # Continue to action 1
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.byte 1 # >> Action Record 3 <<
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.byte 0 # No further actions
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.p2align 2
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.Ltmp6: # TypeInfo 1
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.long .L_ZTISt13runtime_error.DW.stub-.Ltmp6
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.Lttbase0:
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.p2align 2
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.type .L.str,@object # @.str
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.section .rodata.str1.1,"aMS",@progbits,1
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.L.str:
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.asciz "failed successfully"
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.size .L.str, 20
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.data
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.p2align 3
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.L_ZTISt13runtime_error.DW.stub:
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.quad _ZTISt13runtime_error
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.hidden DW.ref.__gxx_personality_v0
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.weak DW.ref.__gxx_personality_v0
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.section .data.DW.ref.__gxx_personality_v0,"aGw",@progbits,DW.ref.__gxx_personality_v0,comdat
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.p2align 3
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.type DW.ref.__gxx_personality_v0,@object
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.size DW.ref.__gxx_personality_v0, 8
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DW.ref.__gxx_personality_v0:
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.quad __gxx_personality_v0
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.ident "clang version 14.0.0 (https://github.com/llvm/llvm-project.git 329fda39c507e8740978d10458451dcdb21563be)"
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.section ".note.GNU-stack","",@progbits
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.addrsig
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.addrsig_sym __gxx_personality_v0
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.addrsig_sym _Unwind_Resume
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.addrsig_sym _ZTISt13runtime_error
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# #include <cstdio>
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# #include <stdexcept>
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#
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# int main() {
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# try {
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# throw std::runtime_error("failed successfully");
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# } catch (const std::runtime_error &e) {
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# puts(e.what());
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# }
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# return 0;
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# }
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