Gordon Henriksen 8fa8929177 With this patch, the LowerGC transformation becomes the ... 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		2008-01-07 01:30:53 +00:00
..
SemiSpace	With this patch, the LowerGC transformation becomes the	2008-01-07 01:30:53 +00:00
gc_exported_symbols.lst	Undo removal of the runtime libraries. While this may have been a bit	2006-11-17 03:32:33 +00:00
GCInterface.h	remove attribution from a variety of miscellaneous files.	2007-12-29 22:59:10 +00:00
Makefile	remove attributions from the rest of the llvm makefiles.	2007-12-29 20:11:13 +00:00