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8fa8929177
ShadowStackCollector, which additionally has reduced overhead with
no sacrifice in portability.
Considering a function @fun with 8 loop-local roots,
ShadowStackCollector introduces the following overhead
(x86):
; shadowstack prologue
movl L_llvm_gc_root_chain$non_lazy_ptr, %eax
movl (%eax), %ecx
movl $___gc_fun, 20(%esp)
movl $0, 24(%esp)
movl $0, 28(%esp)
movl $0, 32(%esp)
movl $0, 36(%esp)
movl $0, 40(%esp)
movl $0, 44(%esp)
movl $0, 48(%esp)
movl $0, 52(%esp)
movl %ecx, 16(%esp)
leal 16(%esp), %ecx
movl %ecx, (%eax)
; shadowstack loop overhead
(none)
; shadowstack epilogue
movl 48(%esp), %edx
movl %edx, (%ecx)
; shadowstack metadata
.align 3
___gc_fun: # __gc_fun
.long 8
.space 4
In comparison to LowerGC:
; lowergc prologue
movl L_llvm_gc_root_chain$non_lazy_ptr, %eax
movl (%eax), %ecx
movl %ecx, 48(%esp)
movl $8, 52(%esp)
movl $0, 60(%esp)
movl $0, 56(%esp)
movl $0, 68(%esp)
movl $0, 64(%esp)
movl $0, 76(%esp)
movl $0, 72(%esp)
movl $0, 84(%esp)
movl $0, 80(%esp)
movl $0, 92(%esp)
movl $0, 88(%esp)
movl $0, 100(%esp)
movl $0, 96(%esp)
movl $0, 108(%esp)
movl $0, 104(%esp)
movl $0, 116(%esp)
movl $0, 112(%esp)
; lowergc loop overhead
leal 44(%esp), %eax
movl %eax, 56(%esp)
leal 40(%esp), %eax
movl %eax, 64(%esp)
leal 36(%esp), %eax
movl %eax, 72(%esp)
leal 32(%esp), %eax
movl %eax, 80(%esp)
leal 28(%esp), %eax
movl %eax, 88(%esp)
leal 24(%esp), %eax
movl %eax, 96(%esp)
leal 20(%esp), %eax
movl %eax, 104(%esp)
leal 16(%esp), %eax
movl %eax, 112(%esp)
; lowergc epilogue
movl 48(%esp), %edx
movl %edx, (%ecx)
; lowergc metadata
(none)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@45670 91177308-0d34-0410-b5e6-96231b3b80d8
51 lines
1.8 KiB
C++
51 lines
1.8 KiB
C++
//===- llvm/Codegen/LinkAllCodegenComponents.h ------------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This header file pulls in all codegen related passes for tools like lli and
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// llc that need this functionality.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_CODEGEN_LINKALLCODEGENCOMPONENTS_H
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#define LLVM_CODEGEN_LINKALLCODEGENCOMPONENTS_H
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/CodeGen/ScheduleDAG.h"
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#include "llvm/CodeGen/Collectors.h"
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namespace {
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struct ForceCodegenLinking {
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ForceCodegenLinking() {
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// We must reference the passes in such a way that compilers will not
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// delete it all as dead code, even with whole program optimization,
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// yet is effectively a NO-OP. As the compiler isn't smart enough
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// to know that getenv() never returns -1, this will do the job.
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if (std::getenv("bar") != (char*) -1)
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return;
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(void) llvm::createSimpleRegisterAllocator();
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(void) llvm::createLocalRegisterAllocator();
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(void) llvm::createBigBlockRegisterAllocator();
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(void) llvm::createLinearScanRegisterAllocator();
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(void) llvm::createSimpleRegisterCoalescer();
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(void) llvm::createShadowStackCollector();
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(void) llvm::createBURRListDAGScheduler(NULL, NULL, NULL);
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(void) llvm::createTDRRListDAGScheduler(NULL, NULL, NULL);
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(void) llvm::createTDListDAGScheduler(NULL, NULL, NULL);
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(void) llvm::createDefaultScheduler(NULL, NULL, NULL);
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}
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} ForceCodegenLinking; // Force link by creating a global definition.
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}
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#endif
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