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.
120 lines
4.5 KiB
LLVM
120 lines
4.5 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=i386-pc-windows-msvc < %s -o - | FileCheck -check-prefix=MSVC-X86 %s
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; RUN: llc -mtriple=x86_64-pc-windows-msvc < %s -o - | FileCheck -check-prefix=MSVC-X64 %s
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; Make sure fastisel falls back and does something secure.
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; RUN: llc -mtriple=i686-pc-windows-msvc -O0 < %s -o - | FileCheck -check-prefix=MSVC-X86-O0 %s
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; RUN: llc -mtriple=x86_64-pc-windows-msvc -O0 < %s -o - | FileCheck -check-prefix=MSVC-X64-O0 %s
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@"\01LC" = internal constant [11 x i8] c"buf == %s\0A\00" ; <ptr> [#uses=1]
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define void @test(ptr %a) nounwind ssp minsize {
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; MSVC-X86-LABEL: test:
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; MSVC-X86: # %bb.0: # %entry
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; MSVC-X86-NEXT: pushl %esi
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; MSVC-X86-NEXT: subl $12, %esp
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; MSVC-X86-NEXT: movl ___security_cookie, %eax
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; MSVC-X86-NEXT: xorl %esp, %eax
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; MSVC-X86-NEXT: movl %eax, {{[0-9]+}}(%esp)
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; MSVC-X86-NEXT: movl %esp, %esi
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; MSVC-X86-NEXT: pushl {{[0-9]+}}(%esp)
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; MSVC-X86-NEXT: pushl %esi
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; MSVC-X86-NEXT: calll _strcpy
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; MSVC-X86-NEXT: popl %ecx
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; MSVC-X86-NEXT: popl %edx
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; MSVC-X86-NEXT: pushl %esi
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; MSVC-X86-NEXT: pushl $LC
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; MSVC-X86-NEXT: calll _printf
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; MSVC-X86-NEXT: popl %ecx
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; MSVC-X86-NEXT: popl %edx
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; MSVC-X86-NEXT: movl {{[0-9]+}}(%esp), %ecx
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; MSVC-X86-NEXT: xorl %esp, %ecx
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; MSVC-X86-NEXT: calll @__security_check_cookie@4
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; MSVC-X86-NEXT: addl $12, %esp
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; MSVC-X86-NEXT: popl %esi
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; MSVC-X86-NEXT: retl
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;
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; MSVC-X64-LABEL: test:
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; MSVC-X64: # %bb.0: # %entry
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; MSVC-X64-NEXT: pushq %rsi
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; MSVC-X64-NEXT: subq $64, %rsp
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; MSVC-X64-NEXT: movq %rcx, %rdx
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; MSVC-X64-NEXT: movq __security_cookie(%rip), %rax
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; MSVC-X64-NEXT: xorq %rsp, %rax
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; MSVC-X64-NEXT: movq %rax, {{[0-9]+}}(%rsp)
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; MSVC-X64-NEXT: movq %rcx, {{[0-9]+}}(%rsp)
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; MSVC-X64-NEXT: leaq {{[0-9]+}}(%rsp), %rsi
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; MSVC-X64-NEXT: movq %rsi, %rcx
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; MSVC-X64-NEXT: callq strcpy
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; MSVC-X64-NEXT: leaq LC(%rip), %rcx
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; MSVC-X64-NEXT: movq %rsi, %rdx
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; MSVC-X64-NEXT: callq printf
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; MSVC-X64-NEXT: movq {{[0-9]+}}(%rsp), %rcx
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; MSVC-X64-NEXT: xorq %rsp, %rcx
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; MSVC-X64-NEXT: callq __security_check_cookie
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; MSVC-X64-NEXT: addq $64, %rsp
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; MSVC-X64-NEXT: popq %rsi
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; MSVC-X64-NEXT: retq
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;
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; MSVC-X86-O0-LABEL: test:
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; MSVC-X86-O0: # %bb.0: # %entry
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; MSVC-X86-O0-NEXT: subl $20, %esp
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; MSVC-X86-O0-NEXT: movl {{[0-9]+}}(%esp), %eax
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; MSVC-X86-O0-NEXT: movl ___security_cookie, %eax
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; MSVC-X86-O0-NEXT: xorl %esp, %eax
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; MSVC-X86-O0-NEXT: movl %eax, {{[0-9]+}}(%esp)
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; MSVC-X86-O0-NEXT: movl {{[0-9]+}}(%esp), %ecx
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; MSVC-X86-O0-NEXT: movl %esp, %eax
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; MSVC-X86-O0-NEXT: movl %ecx, 4(%eax)
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; MSVC-X86-O0-NEXT: leal {{[0-9]+}}(%esp), %ecx
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; MSVC-X86-O0-NEXT: movl %ecx, (%eax)
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; MSVC-X86-O0-NEXT: calll _strcpy
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; MSVC-X86-O0-NEXT: leal LC, %ecx
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; MSVC-X86-O0-NEXT: leal {{[0-9]+}}(%esp), %eax
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; MSVC-X86-O0-NEXT: movl %ecx, (%esp)
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; MSVC-X86-O0-NEXT: movl %eax, {{[0-9]+}}(%esp)
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; MSVC-X86-O0-NEXT: calll _printf
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; MSVC-X86-O0-NEXT: # %bb.1: # %return
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; MSVC-X86-O0-NEXT: movl {{[0-9]+}}(%esp), %ecx
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; MSVC-X86-O0-NEXT: xorl %esp, %ecx
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; MSVC-X86-O0-NEXT: calll @__security_check_cookie@4
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; MSVC-X86-O0-NEXT: addl $20, %esp
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; MSVC-X86-O0-NEXT: retl
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;
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; MSVC-X64-O0-LABEL: test:
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; MSVC-X64-O0: # %bb.0: # %entry
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; MSVC-X64-O0-NEXT: subq $56, %rsp
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; MSVC-X64-O0-NEXT: movq __security_cookie(%rip), %rax
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; MSVC-X64-O0-NEXT: xorq %rsp, %rax
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; MSVC-X64-O0-NEXT: movq %rax, {{[0-9]+}}(%rsp)
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; MSVC-X64-O0-NEXT: movq %rcx, {{[0-9]+}}(%rsp)
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; MSVC-X64-O0-NEXT: movq {{[0-9]+}}(%rsp), %rdx
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; MSVC-X64-O0-NEXT: leaq {{[0-9]+}}(%rsp), %rcx
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; MSVC-X64-O0-NEXT: callq strcpy
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; MSVC-X64-O0-NEXT: leaq LC(%rip), %rcx
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; MSVC-X64-O0-NEXT: leaq {{[0-9]+}}(%rsp), %rdx
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; MSVC-X64-O0-NEXT: callq printf
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; MSVC-X64-O0-NEXT: # %bb.1: # %return
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; MSVC-X64-O0-NEXT: movq {{[0-9]+}}(%rsp), %rcx
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; MSVC-X64-O0-NEXT: xorq %rsp, %rcx
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; MSVC-X64-O0-NEXT: callq __security_check_cookie
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; MSVC-X64-O0-NEXT: addq $56, %rsp
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; MSVC-X64-O0-NEXT: retq
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entry:
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%a_addr = alloca ptr ; <ptr> [#uses=2]
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%buf = alloca [8 x i8] ; <ptr> [#uses=2]
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store ptr %a, ptr %a_addr
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%0 = load ptr, ptr %a_addr, align 4 ; <ptr> [#uses=1]
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%1 = call ptr @strcpy(ptr %buf, ptr %0) nounwind ; <ptr> [#uses=0]
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%2 = call i32 (ptr, ...) @printf(ptr @"\01LC", ptr %buf) nounwind ; <i32> [#uses=0]
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br label %return
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return: ; preds = %entry
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ret void
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}
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declare ptr @strcpy(ptr, ptr) nounwind
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declare i32 @printf(ptr, ...) nounwind
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