[pypy-commit] pypy default: Change FORCE_TOKEN in the x86 backend to return the register 'ebp'

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r47078:906f5d65a98b
Date: 2011-09-05 10:38 +0200
http://bitbucket.org/pypy/pypy/changeset/906f5d65a98b/

Log:	Change FORCE_TOKEN in the x86 backend to return the register 'ebp'
	directly, thus not producing any code at all.

diff --git a/pypy/jit/backend/llsupport/regalloc.py b/pypy/jit/backend/llsupport/regalloc.py
--- a/pypy/jit/backend/llsupport/regalloc.py
+++ b/pypy/jit/backend/llsupport/regalloc.py
@@ -57,11 +57,13 @@
     all_regs              = []
     no_lower_byte_regs    = []
     save_around_call_regs = []
-    
+    frame_reg             = None
+
     def __init__(self, longevity, frame_manager=None, assembler=None):
         self.free_regs = self.all_regs[:]
         self.longevity = longevity
         self.reg_bindings = {}
+        self.bindings_to_frame_reg = {}
         self.position = -1
         self.frame_manager = frame_manager
         self.assembler = assembler
@@ -218,6 +220,10 @@
         self.reg_bindings[v] = loc
         return loc
 
+    def force_allocate_frame_reg(self, v):
+        """ Allocate the new variable v in the frame register."""
+        self.bindings_to_frame_reg[v] = None
+
     def force_spill_var(self, var):
         self._sync_var(var)
         try:
@@ -236,6 +242,8 @@
         try:
             return self.reg_bindings[box]
         except KeyError:
+            if box in self.bindings_to_frame_reg:
+                return self.frame_reg
             return self.frame_manager.loc(box)
 
     def return_constant(self, v, forbidden_vars=[], selected_reg=None):
@@ -264,8 +272,9 @@
         self._check_type(v)
         if isinstance(v, Const):
             return self.return_constant(v, forbidden_vars, selected_reg)
-        
         prev_loc = self.loc(v)
+        if prev_loc is self.frame_reg and selected_reg is None:
+            return prev_loc
         loc = self.force_allocate_reg(v, forbidden_vars, selected_reg,
                                       need_lower_byte=need_lower_byte)
         if prev_loc is not loc:
diff --git a/pypy/jit/backend/x86/assembler.py b/pypy/jit/backend/x86/assembler.py
--- a/pypy/jit/backend/x86/assembler.py
+++ b/pypy/jit/backend/x86/assembler.py
@@ -2510,11 +2510,6 @@
 
     genop_discard_cond_call_gc_wb_array = genop_discard_cond_call_gc_wb
 
-    def genop_force_token(self, op, arglocs, resloc):
-        # RegAlloc.consider_force_token ensures this:
-        assert isinstance(resloc, RegLoc)
-        self.mc.LEA_rb(resloc.value, FORCE_INDEX_OFS)
-
     def not_implemented_op_discard(self, op, arglocs):
         not_implemented("not implemented operation: %s" % op.getopname())
 
diff --git a/pypy/jit/backend/x86/regalloc.py b/pypy/jit/backend/x86/regalloc.py
--- a/pypy/jit/backend/x86/regalloc.py
+++ b/pypy/jit/backend/x86/regalloc.py
@@ -29,6 +29,7 @@
     all_regs = [eax, ecx, edx, ebx, esi, edi]
     no_lower_byte_regs = [esi, edi]
     save_around_call_regs = [eax, edx, ecx]
+    frame_reg = ebp
 
     REGLOC_TO_GCROOTMAP_REG_INDEX = {
         ebx: 1,
@@ -1358,8 +1359,8 @@
                                             self.assembler.datablockwrapper)
 
     def consider_force_token(self, op):
-        loc = self.rm.force_allocate_reg(op.result)
-        self.Perform(op, [], loc)
+        # the FORCE_TOKEN operation returns directly 'ebp'
+        self.rm.force_allocate_frame_reg(op.result)
 
     def not_implemented_op(self, op):
         not_implemented("not implemented operation: %s" % op.getopname())
diff --git a/pypy/jit/backend/x86/runner.py b/pypy/jit/backend/x86/runner.py
--- a/pypy/jit/backend/x86/runner.py
+++ b/pypy/jit/backend/x86/runner.py
@@ -119,7 +119,8 @@
             setitem(index, null)
 
     def get_latest_force_token(self):
-        return self.assembler.fail_ebp + FORCE_INDEX_OFS
+        # the FORCE_TOKEN operation and this helper both return 'ebp'.
+        return self.assembler.fail_ebp
 
     def execute_token(self, executable_token):
         addr = executable_token._x86_bootstrap_code
@@ -153,8 +154,9 @@
                                        flavor='raw', zero=True,
                                        immortal=True)
 
-    def force(self, addr_of_force_index):
+    def force(self, addr_of_force_token):
         TP = rffi.CArrayPtr(lltype.Signed)
+        addr_of_force_index = addr_of_force_token + FORCE_INDEX_OFS
         fail_index = rffi.cast(TP, addr_of_force_index)[0]
         assert fail_index >= 0, "already forced!"
         faildescr = self.get_fail_descr_from_number(fail_index)
@@ -164,7 +166,7 @@
         # start of "no gc operation!" block
         fail_index_2 = self.assembler.grab_frame_values(
             bytecode,
-            addr_of_force_index - FORCE_INDEX_OFS,
+            addr_of_force_token,
             self.all_null_registers)
         self.assembler.leave_jitted_hook()
         # end of "no gc operation!" block