Author: Armin Rigo <[email protected]>
Branch:
Changeset: r91422:a88434fd16b8
Date: 2017-05-27 12:52 +0100
http://bitbucket.org/pypy/pypy/changeset/a88434fd16b8/
Log: Add a marker into the shadowstack from the JIT. Might improve
performance in some cases
diff --git a/rpython/jit/backend/x86/assembler.py
b/rpython/jit/backend/x86/assembler.py
--- a/rpython/jit/backend/x86/assembler.py
+++ b/rpython/jit/backend/x86/assembler.py
@@ -1052,17 +1052,19 @@
def _call_header_shadowstack(self, gcrootmap):
rst = self._load_shadowstack_top_in_ebx(self.mc, gcrootmap)
- self.mc.MOV_mr((ebx.value, 0), ebp.value) # MOV [ebx], ebp
- self.mc.ADD_ri(ebx.value, WORD)
+ # the '1' is to benefit from the shadowstack 'is_minor' optimization
+ self.mc.MOV_mi((ebx.value, 0), 1) # MOV [ebx], 1
+ self.mc.MOV_mr((ebx.value, WORD), ebp.value) # MOV [ebx + WORD], ebp
+ self.mc.ADD_ri(ebx.value, WORD * 2)
self.mc.MOV(heap(rst), ebx) # MOV [rootstacktop], ebx
def _call_footer_shadowstack(self, gcrootmap):
rst = gcrootmap.get_root_stack_top_addr()
if rx86.fits_in_32bits(rst):
- self.mc.SUB_ji8(rst, WORD) # SUB [rootstacktop], WORD
+ self.mc.SUB_ji8(rst, WORD * 2) # SUB [rootstacktop], WORD * 2
else:
self.mc.MOV_ri(ebx.value, rst) # MOV ebx, rootstacktop
- self.mc.SUB_mi8((ebx.value, 0), WORD) # SUB [ebx], WORD
+ self.mc.SUB_mi8((ebx.value, 0), WORD * 2) # SUB [ebx], WORD * 2
def redirect_call_assembler(self, oldlooptoken, newlooptoken):
# some minimal sanity checking
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