e1e1836bbd
This patch optimizes the Windows security cookie check mechanism by moving the comparison inline and only calling __security_check_cookie when the check fails. This reduces the overhead of making a DLL call for every function return. Previously, we implemented this optimization through a machine pass (X86WinFixupBufferSecurityCheckPass) in PR #95904 submitted by @mahesh-attarde. We have reverted that pass in favor of this new approach. Also we have abandoned the AArch64 specific implementation of same pass in PR #121938 in favor of this more general solution. The old machine instruction pass approach: - Scanned the generated code to find __security_check_cookie calls - Modified these calls by splitting basic blocks - Added comparison logic and conditional branching - Required complex block management and live register computation The new approach: - Implements the same optimization during instruction selection - Directly emits the comparison and conditional branching - No need for post-processing or basic block manipulation - Disables optimization at -Oz. Thanks @tamaspetz, @efriedma-quic and @arsenm for their help.
164 lines
5.4 KiB
LLVM
164 lines
5.4 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
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; RUN: llc -mtriple=x86_64-windows-msvc %s -o - -verify-machineinstrs | FileCheck %s -check-prefix=WINDOWS
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; RUN: llc -mtriple=x86_64-linux-gnu %s -o - -verify-machineinstrs | FileCheck %s -check-prefix=LINUX
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declare void @h(ptr, i64, ptr)
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define tailcc void @tailcall_frame(ptr %0, i64 %1) sspreq {
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; WINDOWS-LABEL: tailcall_frame:
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; WINDOWS: # %bb.0:
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; WINDOWS-NEXT: subq $56, %rsp
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; WINDOWS-NEXT: .seh_stackalloc 56
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; WINDOWS-NEXT: .seh_endprologue
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; WINDOWS-NEXT: movq __security_cookie(%rip), %rax
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; WINDOWS-NEXT: xorq %rsp, %rax
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; WINDOWS-NEXT: movq %rax, {{[0-9]+}}(%rsp)
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; WINDOWS-NEXT: movq {{[0-9]+}}(%rsp), %rax
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; WINDOWS-NEXT: xorq %rsp, %rax
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; WINDOWS-NEXT: movq __security_cookie(%rip), %rcx
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; WINDOWS-NEXT: cmpq %rax, %rcx
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; WINDOWS-NEXT: jne .LBB0_1
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; WINDOWS-NEXT: # %bb.2:
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; WINDOWS-NEXT: xorl %ecx, %ecx
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; WINDOWS-NEXT: xorl %edx, %edx
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; WINDOWS-NEXT: xorl %r8d, %r8d
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; WINDOWS-NEXT: .seh_startepilogue
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; WINDOWS-NEXT: addq $56, %rsp
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; WINDOWS-NEXT: .seh_endepilogue
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; WINDOWS-NEXT: jmp h # TAILCALL
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; WINDOWS-NEXT: .LBB0_1:
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; WINDOWS-NEXT: movq {{[0-9]+}}(%rsp), %rcx
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; WINDOWS-NEXT: xorq %rsp, %rcx
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; WINDOWS-NEXT: callq __security_check_cookie
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; WINDOWS-NEXT: int3
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; WINDOWS-NEXT: .seh_endproc
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;
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; LINUX-LABEL: tailcall_frame:
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; LINUX: # %bb.0:
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; LINUX-NEXT: subq $24, %rsp
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; LINUX-NEXT: .cfi_def_cfa_offset 32
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; LINUX-NEXT: movq %fs:40, %rax
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; LINUX-NEXT: movq %rax, {{[0-9]+}}(%rsp)
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; LINUX-NEXT: movq %fs:40, %rax
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; LINUX-NEXT: cmpq {{[0-9]+}}(%rsp), %rax
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; LINUX-NEXT: jne .LBB0_2
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; LINUX-NEXT: # %bb.1: # %SP_return
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; LINUX-NEXT: xorl %edi, %edi
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; LINUX-NEXT: xorl %esi, %esi
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; LINUX-NEXT: xorl %edx, %edx
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; LINUX-NEXT: addq $24, %rsp
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; LINUX-NEXT: .cfi_def_cfa_offset 8
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; LINUX-NEXT: jmp h@PLT # TAILCALL
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; LINUX-NEXT: .LBB0_2: # %CallStackCheckFailBlk
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; LINUX-NEXT: .cfi_def_cfa_offset 32
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; LINUX-NEXT: callq __stack_chk_fail@PLT
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tail call tailcc void @h(ptr null, i64 0, ptr null)
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ret void
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}
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declare void @bar()
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define void @tailcall_unrelated_frame() sspreq {
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; WINDOWS-LABEL: tailcall_unrelated_frame:
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; WINDOWS: # %bb.0:
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; WINDOWS-NEXT: subq $40, %rsp
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; WINDOWS-NEXT: .seh_stackalloc 40
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; WINDOWS-NEXT: .seh_endprologue
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; WINDOWS-NEXT: movq __security_cookie(%rip), %rax
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; WINDOWS-NEXT: xorq %rsp, %rax
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; WINDOWS-NEXT: movq %rax, {{[0-9]+}}(%rsp)
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; WINDOWS-NEXT: callq bar
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; WINDOWS-NEXT: movq {{[0-9]+}}(%rsp), %rax
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; WINDOWS-NEXT: xorq %rsp, %rax
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; WINDOWS-NEXT: movq __security_cookie(%rip), %rcx
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; WINDOWS-NEXT: cmpq %rax, %rcx
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; WINDOWS-NEXT: jne .LBB1_1
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; WINDOWS-NEXT: # %bb.2:
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; WINDOWS-NEXT: .seh_startepilogue
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; WINDOWS-NEXT: addq $40, %rsp
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; WINDOWS-NEXT: .seh_endepilogue
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; WINDOWS-NEXT: jmp bar # TAILCALL
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; WINDOWS-NEXT: .LBB1_1:
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; WINDOWS-NEXT: movq {{[0-9]+}}(%rsp), %rcx
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; WINDOWS-NEXT: xorq %rsp, %rcx
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; WINDOWS-NEXT: callq __security_check_cookie
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; WINDOWS-NEXT: int3
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; WINDOWS-NEXT: .seh_endproc
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;
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; LINUX-LABEL: tailcall_unrelated_frame:
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; LINUX: # %bb.0:
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; LINUX-NEXT: pushq %rax
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; LINUX-NEXT: .cfi_def_cfa_offset 16
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; LINUX-NEXT: movq %fs:40, %rax
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; LINUX-NEXT: movq %rax, (%rsp)
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; LINUX-NEXT: callq bar@PLT
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; LINUX-NEXT: movq %fs:40, %rax
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; LINUX-NEXT: cmpq (%rsp), %rax
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; LINUX-NEXT: jne .LBB1_2
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; LINUX-NEXT: # %bb.1: # %SP_return
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; LINUX-NEXT: popq %rax
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; LINUX-NEXT: .cfi_def_cfa_offset 8
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; LINUX-NEXT: jmp bar@PLT # TAILCALL
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; LINUX-NEXT: .LBB1_2: # %CallStackCheckFailBlk
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; LINUX-NEXT: .cfi_def_cfa_offset 16
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; LINUX-NEXT: callq __stack_chk_fail@PLT
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call void @bar()
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tail call void @bar()
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ret void
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}
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declare void @callee()
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define void @caller() sspreq {
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; WINDOWS-LABEL: caller:
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; WINDOWS: # %bb.0:
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; WINDOWS-NEXT: subq $40, %rsp
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; WINDOWS-NEXT: .seh_stackalloc 40
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; WINDOWS-NEXT: .seh_endprologue
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; WINDOWS-NEXT: movq __security_cookie(%rip), %rax
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; WINDOWS-NEXT: xorq %rsp, %rax
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; WINDOWS-NEXT: movq %rax, {{[0-9]+}}(%rsp)
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; WINDOWS-NEXT: callq callee
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; WINDOWS-NEXT: callq callee
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; WINDOWS-NEXT: movq {{[0-9]+}}(%rsp), %rax
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; WINDOWS-NEXT: xorq %rsp, %rax
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; WINDOWS-NEXT: movq __security_cookie(%rip), %rcx
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; WINDOWS-NEXT: cmpq %rax, %rcx
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; WINDOWS-NEXT: jne .LBB2_2
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; WINDOWS-NEXT: # %bb.1:
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; WINDOWS-NEXT: .seh_startepilogue
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; WINDOWS-NEXT: addq $40, %rsp
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; WINDOWS-NEXT: .seh_endepilogue
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; WINDOWS-NEXT: retq
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; WINDOWS-NEXT: .LBB2_2:
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; WINDOWS-NEXT: movq {{[0-9]+}}(%rsp), %rcx
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; WINDOWS-NEXT: xorq %rsp, %rcx
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; WINDOWS-NEXT: callq __security_check_cookie
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; WINDOWS-NEXT: int3
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; WINDOWS-NEXT: .seh_endproc
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;
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; LINUX-LABEL: caller:
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; LINUX: # %bb.0:
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; LINUX-NEXT: pushq %rax
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; LINUX-NEXT: .cfi_def_cfa_offset 16
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; LINUX-NEXT: movq %fs:40, %rax
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; LINUX-NEXT: movq %rax, (%rsp)
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; LINUX-NEXT: callq callee@PLT
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; LINUX-NEXT: callq callee@PLT
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; LINUX-NEXT: movq %fs:40, %rax
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; LINUX-NEXT: cmpq (%rsp), %rax
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; LINUX-NEXT: jne .LBB2_2
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; LINUX-NEXT: # %bb.1: # %SP_return
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; LINUX-NEXT: popq %rax
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; LINUX-NEXT: .cfi_def_cfa_offset 8
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; LINUX-NEXT: retq
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; LINUX-NEXT: .LBB2_2: # %CallStackCheckFailBlk
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; LINUX-NEXT: .cfi_def_cfa_offset 16
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; LINUX-NEXT: callq __stack_chk_fail@PLT
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tail call void @callee()
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call void @callee()
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ret void
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}
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