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author | Jeremy Hylton <jeremy@alum.mit.edu> | 2001-04-12 20:21:39 (GMT) |
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committer | Jeremy Hylton <jeremy@alum.mit.edu> | 2001-04-12 20:21:39 (GMT) |
commit | 542b11acfd5309438ed2769be1fc476b9597f1fb (patch) | |
tree | a6ed2a4207c9421d884b6a171f988cb1ae2b3d8e /Lib | |
parent | 35cf0a3f90de8f2e3597e67701d1e03dd11a8cbe (diff) | |
download | cpython-542b11acfd5309438ed2769be1fc476b9597f1fb.zip cpython-542b11acfd5309438ed2769be1fc476b9597f1fb.tar.gz cpython-542b11acfd5309438ed2769be1fc476b9597f1fb.tar.bz2 |
pyassem.py:
Fix annoying bugs in flow graph layout code. In some cases the
implicit control transfers weren't honored. In other cases,
JUMP_FORWARD instructions jumped backwards.
Remove unused arg from nextBlock().
pycodegen.py
Add optional force kwarg to set_lineno() that will emit a
SET_LINENO even if it is the same as the previous lineno.
Use explicit LOAD_FAST and STORE_FAST to access list comp implicit
variables. (The symbol table doesn't know about them.)
Diffstat (limited to 'Lib')
-rw-r--r-- | Lib/compiler/pyassem.py | 101 | ||||
-rw-r--r-- | Lib/compiler/pycodegen.py | 24 |
2 files changed, 111 insertions, 14 deletions
diff --git a/Lib/compiler/pyassem.py b/Lib/compiler/pyassem.py index 15e91f4..e8810ae 100644 --- a/Lib/compiler/pyassem.py +++ b/Lib/compiler/pyassem.py @@ -27,11 +27,12 @@ class FlowGraph: if self._debug: if self.current: print "end", repr(self.current) + print " next", self.current.next print " ", self.current.get_children() print repr(block) self.current = block - def nextBlock(self, block=None, force=0): + def nextBlock(self, block=None): # XXX think we need to specify when there is implicit transfer # from one block to the next. might be better to represent this # with explicit JUMP_ABSOLUTE instructions that are optimized @@ -95,12 +96,110 @@ class FlowGraph: b.addNext(self.exit) order = dfs_postorder(self.entry, {}) order.reverse() + self.fixupOrder(order, self.exit) # hack alert if not self.exit in order: order.append(self.exit) return order + def fixupOrder(self, blocks, default_next): + """Fixup bad order introduced by DFS.""" + + # XXX This is a total mess. There must be a better way to get + # the code blocks in the right order. + + self.fixupOrderHonorNext(blocks, default_next) + self.fixupOrderForward(blocks, default_next) + + def fixupOrderHonorNext(self, blocks, default_next): + """Fix one problem with DFS. + + The DFS uses child block, but doesn't know about the special + "next" block. As a result, the DFS can order blocks so that a + block isn't next to the right block for implicit control + transfers. + """ + index = {} + for i in range(len(blocks)): + index[blocks[i]] = i + + for i in range(0, len(blocks) - 1): + b = blocks[i] + n = blocks[i + 1] + if not b.next or b.next[0] == default_next or b.next[0] == n: + continue + # The blocks are in the wrong order. Find the chain of + # blocks to insert where they belong. + cur = b + chain = [] + elt = cur + while elt.next and elt.next[0] != default_next: + chain.append(elt.next[0]) + elt = elt.next[0] + # Now remove the blocks in the chain from the current + # block list, so that they can be re-inserted. + l = [] + for b in chain: + assert index[b] > i + l.append((index[b], b)) + l.sort() + l.reverse() + for j, b in l: + del blocks[index[b]] + # Insert the chain in the proper location + blocks[i:i + 1] = [cur] + chain + # Finally, re-compute the block indexes + for i in range(len(blocks)): + index[blocks[i]] = i + + def fixupOrderForward(self, blocks, default_next): + """Make sure all JUMP_FORWARDs jump forward""" + index = {} + chains = [] + cur = [] + for b in blocks: + index[b] = len(chains) + cur.append(b) + if b.next and b.next[0] == default_next: + chains.append(cur) + cur = [] + chains.append(cur) + + while 1: + constraints = [] + + for i in range(len(chains)): + l = chains[i] + for b in l: + for c in b.get_children(): + if index[c] < i: + forward_p = 0 + for inst in b.insts: + if inst[0] == 'JUMP_FORWARD': + if inst[1] == c: + forward_p = 1 + if not forward_p: + continue + constraints.append((index[c], i)) + + if not constraints: + break + + # XXX just do one for now + # do swaps to get things in the right order + goes_before, a_chain = constraints[0] + assert a_chain > goes_before + c = chains[a_chain] + chains.remove(c) + chains.insert(goes_before, c) + + + del blocks[:] + for c in chains: + for b in c: + blocks.append(b) + def getBlocks(self): return self.blocks.elements() diff --git a/Lib/compiler/pycodegen.py b/Lib/compiler/pycodegen.py index 691232f..63b0a57 100644 --- a/Lib/compiler/pycodegen.py +++ b/Lib/compiler/pycodegen.py @@ -193,7 +193,7 @@ class CodeGenerator: else: self.emit(prefix + '_GLOBAL', name) - def set_lineno(self, node): + def set_lineno(self, node, force=0): """Emit SET_LINENO if node has lineno attribute and it is different than the last lineno emitted. @@ -205,7 +205,8 @@ class CodeGenerator: then, this method works around missing line numbers. """ lineno = getattr(node, 'lineno', None) - if lineno is not None and lineno != self.last_lineno: + if lineno is not None and (lineno != self.last_lineno + or force): self.emit('SET_LINENO', lineno) self.last_lineno = lineno return 1 @@ -413,9 +414,6 @@ class CodeGenerator: __list_count = 0 def visitListComp(self, node): - # XXX would it be easier to transform the AST into the form it - # would have if the list comp were expressed as a series of - # for and if stmts and an explicit append? self.set_lineno(node) # setup list append = "$append%d" % self.__list_count @@ -423,10 +421,10 @@ class CodeGenerator: self.emit('BUILD_LIST', 0) self.emit('DUP_TOP') self.emit('LOAD_ATTR', 'append') - self.storeName(append) - l = len(node.quals) + self.emit('STORE_FAST', append) + stack = [] - for i, for_ in zip(range(l), node.quals): + for i, for_ in zip(range(len(node.quals)), node.quals): start, anchor = self.visit(for_) cont = None for if_ in for_.ifs: @@ -434,8 +432,8 @@ class CodeGenerator: cont = self.newBlock() self.visit(if_, cont) stack.insert(0, (start, cont, anchor)) - - self.loadName(append) + + self.emit('LOAD_FAST', append) self.visit(node.expr) self.emit('CALL_FUNCTION', 1) self.emit('POP_TOP') @@ -449,12 +447,11 @@ class CodeGenerator: self.nextBlock(skip_one) self.emit('JUMP_ABSOLUTE', start) self.startBlock(anchor) - self.delName(append) + self.emit('DELETE_FAST', append) self.__list_count = self.__list_count - 1 def visitListCompFor(self, node): - self.set_lineno(node) start = self.newBlock() anchor = self.newBlock() @@ -468,7 +465,7 @@ class CodeGenerator: return start, anchor def visitListCompIf(self, node, branch): - self.set_lineno(node) + self.set_lineno(node, force=1) self.visit(node.test) self.emit('JUMP_IF_FALSE', branch) self.newBlock() @@ -672,6 +669,7 @@ class CodeGenerator: print node def _visitAssSequence(self, node, op='UNPACK_SEQUENCE'): +## print >> sys.stderr, "AssSequence", op, findOp(node), node if findOp(node) != 'OP_DELETE': self.emit(op, len(node.nodes)) for child in node.nodes: |