82095bd5ed
Mark fragments related to split jump table as non-simple. A function could be splitted into hot and cold fragments. A split jump table is challenging for correctly reconstructing control flow graphs, so it was marked as ignored. This update marks those fragments as non-simple, allowing them to be printed and partial control flow graph construction. Test Plan: ``` llvm-lit -a tools/bolt/test/X86/split-func-icf.s ``` This test has two functions (main, main2), each has a jump table target to the same cold portion main2.cold.1(*2). We try to print out only this cold portion. If it is ignored, it cannot be printed. If it is non-simple, it can be printed. We verify that it can be printed. Reviewed By: Amir Differential Revision: https://reviews.llvm.org/D127464
103 lines
2.4 KiB
ArmAsm
103 lines
2.4 KiB
ArmAsm
# This reproduces an issue where two cold fragments are folded into one, so the
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# fragment has two parents.
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# The fragment is only reachable through a jump table, so all functions must be
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# ignored.
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# REQUIRES: system-linux
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# RUN: llvm-mc -filetype=obj -triple x86_64-unknown-unknown %s -o %t.o
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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.out -v=1 --print-only=main2.cold.1 --print-disasm 2>&1 | FileCheck %s
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# CHECK-NOT: unclaimed PC-relative relocations left in data
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# CHECK-DAG: BOLT-INFO: marking main2.cold.1(*2) as a fragment of main
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# CHECK-DAG: BOLT-INFO: marking main2.cold.1(*2) as a fragment of main2
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# CHECK: Binary Function "main2.cold.1(*2)" after disassembly
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# CHECK: End of Function "main2.cold.1(*2)"
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# CHECK-DAG: BOLT-WARNING: Ignoring main2
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# CHECK-DAG: BOLT-WARNING: Ignoring main
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# CHECK-DAG: BOLT-WARNING: Ignoring main2.cold.1(*2)
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# CHECK: BOLT-WARNING: skipped 3 functions due to cold fragments
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.text
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.globl main
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.type main, %function
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.p2align 2
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main:
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LBB0:
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andl $0xf, %ecx
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cmpb $0x4, %cl
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# exit through ret
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ja LBB3
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# jump table dispatch, jumping to label indexed by val in %ecx
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LBB1:
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leaq JUMP_TABLE1(%rip), %r8
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movzbl %cl, %ecx
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movslq (%r8,%rcx,4), %rax
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addq %rax, %r8
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jmpq *%r8
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LBB2:
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xorq %rax, %rax
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LBB3:
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addq $0x8, %rsp
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ret
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.size main, .-main
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.globl main2
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.type main2, %function
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.p2align 2
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main2:
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LBB20:
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andl $0xb, %ebx
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cmpb $0x1, %cl
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# exit through ret
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ja LBB23
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# jump table dispatch, jumping to label indexed by val in %ecx
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LBB21:
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leaq JUMP_TABLE2(%rip), %r8
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movzbl %cl, %ecx
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movslq (%r8,%rcx,4), %rax
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addq %rax, %r8
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jmpq *%r8
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LBB22:
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xorq %rax, %rax
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LBB23:
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addq $0x8, %rsp
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ret
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.size main2, .-main2
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# cold fragment is only reachable through jump table
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.globl main2.cold.1
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.type main2.cold.1, %function
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main2.cold.1:
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.globl main.cold.1
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.type main.cold.1, %function
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.p2align 2
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main.cold.1:
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# load bearing nop: pad LBB4 so that it can't be treated
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# as __builtin_unreachable by analyzeJumpTable
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nop
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LBB4:
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callq abort
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.size main.cold.1, .-main.cold.1
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.rodata
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# jmp table, entries must be R_X86_64_PC32 relocs
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.globl JUMP_TABLE1
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JUMP_TABLE1:
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.long LBB2-JUMP_TABLE1
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.long LBB3-JUMP_TABLE1
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.long LBB4-JUMP_TABLE1
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.long LBB3-JUMP_TABLE1
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.globl JUMP_TABLE2
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JUMP_TABLE2:
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.long LBB22-JUMP_TABLE2
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.long LBB23-JUMP_TABLE2
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.long LBB4-JUMP_TABLE2
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.long LBB23-JUMP_TABLE2
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