mirror of https://github.com/python/cpython
GH-93444: remove redundant fields from basicblock: b_nofallthrough, b_exit, b_return (GH-93445)
This commit is contained in:
parent
f32e6b48d1
commit
1713ff09d6
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@ -0,0 +1 @@
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Removed redundant fields from the compiler's basicblock struct: ``b_nofallthrough``, ``b_exit``, ``b_return``. They can be easily calculated from the opcode of the last instruction of the block.
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152
Python/compile.c
152
Python/compile.c
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@ -101,6 +101,10 @@
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(opcode) == POP_JUMP_IF_FALSE || \
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(opcode) == POP_JUMP_IF_TRUE)
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#define IS_JUMP_OPCODE(opcode) \
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(IS_VIRTUAL_JUMP_OPCODE(opcode) || \
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is_bit_set_in_table(_PyOpcode_Jump, opcode))
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/* opcodes which are not emitted in codegen stage, only by the assembler */
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#define IS_ASSEMBLER_OPCODE(opcode) \
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((opcode) == JUMP_FORWARD || \
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@ -124,6 +128,17 @@
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(opcode) == POP_JUMP_BACKWARD_IF_TRUE || \
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(opcode) == POP_JUMP_BACKWARD_IF_FALSE)
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#define IS_UNCONDITIONAL_JUMP_OPCODE(opcode) \
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((opcode) == JUMP || \
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(opcode) == JUMP_NO_INTERRUPT || \
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(opcode) == JUMP_FORWARD || \
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(opcode) == JUMP_BACKWARD || \
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(opcode) == JUMP_BACKWARD_NO_INTERRUPT)
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#define IS_SCOPE_EXIT_OPCODE(opcode) \
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((opcode) == RETURN_VALUE || \
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(opcode) == RAISE_VARARGS || \
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(opcode) == RERAISE)
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#define IS_TOP_LEVEL_AWAIT(c) ( \
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(c->c_flags->cf_flags & PyCF_ALLOW_TOP_LEVEL_AWAIT) \
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@ -142,11 +157,6 @@ struct instr {
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int i_end_col_offset;
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};
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typedef struct excepthandler {
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struct instr *setup;
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int offset;
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} ExceptHandler;
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typedef struct exceptstack {
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struct basicblock_ *handlers[CO_MAXBLOCKS+1];
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int depth;
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@ -187,8 +197,7 @@ is_block_push(struct instr *instr)
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static inline int
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is_jump(struct instr *i)
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{
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return IS_VIRTUAL_JUMP_OPCODE(i->i_opcode) ||
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is_bit_set_in_table(_PyOpcode_Jump, i->i_opcode);
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return IS_JUMP_OPCODE(i->i_opcode);
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}
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static int
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@ -254,16 +263,10 @@ typedef struct basicblock_ {
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int b_startdepth;
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/* instruction offset for block, computed by assemble_jump_offsets() */
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int b_offset;
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/* Basic block has no fall through (it ends with a return, raise or jump) */
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unsigned b_nofallthrough : 1;
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/* Basic block is an exception handler that preserves lasti */
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unsigned b_preserve_lasti : 1;
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/* Used by compiler passes to mark whether they have visited a basic block. */
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unsigned b_visited : 1;
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/* Basic block exits scope (it ends with a return or raise) */
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unsigned b_exit : 1;
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/* b_return is true if a RETURN_VALUE opcode is inserted. */
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unsigned b_return : 1;
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/* b_cold is true if this block is not perf critical (like an exception handler) */
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unsigned b_cold : 1;
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/* b_warm is used by the cold-detection algorithm to mark blocks which are definitely not cold */
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@ -279,6 +282,29 @@ basicblock_last_instr(basicblock *b) {
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return NULL;
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}
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static inline int
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basicblock_returns(basicblock *b) {
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struct instr *last = basicblock_last_instr(b);
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return last && last->i_opcode == RETURN_VALUE;
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}
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static inline int
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basicblock_exits_scope(basicblock *b) {
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struct instr *last = basicblock_last_instr(b);
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return last && IS_SCOPE_EXIT_OPCODE(last->i_opcode);
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}
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static inline int
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basicblock_nofallthrough(basicblock *b) {
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struct instr *last = basicblock_last_instr(b);
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return (last &&
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(IS_SCOPE_EXIT_OPCODE(last->i_opcode) ||
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IS_UNCONDITIONAL_JUMP_OPCODE(last->i_opcode)));
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}
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#define BB_NO_FALLTHROUGH(B) (basicblock_nofallthrough(B))
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#define BB_HAS_FALLTHROUGH(B) (!basicblock_nofallthrough(B))
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/* fblockinfo tracks the current frame block.
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A frame block is used to handle loops, try/except, and try/finally.
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@ -852,7 +878,7 @@ compiler_copy_block(struct compiler *c, basicblock *block)
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/* Cannot copy a block if it has a fallthrough, since
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* a block can only have one fallthrough predecessor.
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*/
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assert(block->b_nofallthrough);
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assert(BB_NO_FALLTHROUGH(block));
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basicblock *result = compiler_new_block(c);
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if (result == NULL) {
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return NULL;
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@ -864,8 +890,6 @@ compiler_copy_block(struct compiler *c, basicblock *block)
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}
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result->b_instr[n] = block->b_instr[i];
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}
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result->b_exit = block->b_exit;
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result->b_nofallthrough = 1;
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return result;
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}
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@ -1223,11 +1247,7 @@ static int
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is_end_of_basic_block(struct instr *instr)
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{
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int opcode = instr->i_opcode;
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return is_jump(instr) ||
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opcode == RETURN_VALUE ||
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opcode == RAISE_VARARGS ||
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opcode == RERAISE;
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return is_jump(instr) || IS_SCOPE_EXIT_OPCODE(opcode);
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}
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static int
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@ -1263,9 +1283,6 @@ basicblock_addop_line(basicblock *b, int opcode, int line,
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struct instr *i = &b->b_instr[off];
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i->i_opcode = opcode;
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i->i_oparg = 0;
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if (opcode == RETURN_VALUE) {
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b->b_return = 1;
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}
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i->i_lineno = line;
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i->i_end_lineno = end_line;
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i->i_col_offset = col_offset;
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@ -7144,11 +7161,8 @@ stackdepth(struct compiler *c, basicblock *entry)
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}
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depth = new_depth;
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assert(!IS_ASSEMBLER_OPCODE(instr->i_opcode));
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if (instr->i_opcode == JUMP_NO_INTERRUPT ||
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instr->i_opcode == JUMP ||
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instr->i_opcode == RETURN_VALUE ||
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instr->i_opcode == RAISE_VARARGS ||
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instr->i_opcode == RERAISE)
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if (IS_UNCONDITIONAL_JUMP_OPCODE(instr->i_opcode) ||
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IS_SCOPE_EXIT_OPCODE(instr->i_opcode))
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{
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/* remaining code is dead */
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next = NULL;
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@ -7159,7 +7173,7 @@ stackdepth(struct compiler *c, basicblock *entry)
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}
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}
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if (next != NULL) {
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assert(b->b_nofallthrough == 0);
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assert(BB_HAS_FALLTHROUGH(b));
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stackdepth_push(&sp, next, depth);
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}
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}
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@ -7314,7 +7328,7 @@ label_exception_targets(basicblock *entry) {
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instr->i_except = handler;
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assert(i == b->b_iused -1);
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if (!instr->i_target->b_visited) {
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if (b->b_nofallthrough == 0) {
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if (BB_HAS_FALLTHROUGH(b)) {
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ExceptStack *copy = copy_except_stack(except_stack);
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if (copy == NULL) {
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goto error;
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@ -7334,7 +7348,7 @@ label_exception_targets(basicblock *entry) {
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instr->i_except = handler;
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}
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}
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if (b->b_nofallthrough == 0 && !b->b_next->b_visited) {
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if (BB_HAS_FALLTHROUGH(b) && !b->b_next->b_visited) {
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assert(except_stack != NULL);
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b->b_next->b_exceptstack = except_stack;
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todo[0] = b->b_next;
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@ -7373,7 +7387,7 @@ mark_warm(basicblock *entry) {
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assert(!b->b_except_predecessors);
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b->b_warm = 1;
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basicblock *next = b->b_next;
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if (next && !b->b_nofallthrough && !next->b_visited) {
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if (next && BB_HAS_FALLTHROUGH(b) && !next->b_visited) {
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*sp++ = next;
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next->b_visited = 1;
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}
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@ -7417,7 +7431,7 @@ mark_cold(basicblock *entry) {
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basicblock *b = *(--sp);
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b->b_cold = 1;
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basicblock *next = b->b_next;
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if (next && !b->b_nofallthrough) {
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if (next && BB_HAS_FALLTHROUGH(b)) {
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if (!next->b_warm && !next->b_visited) {
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*sp++ = next;
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next->b_visited = 1;
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@ -7452,7 +7466,7 @@ push_cold_blocks_to_end(struct compiler *c, basicblock *entry, int code_flags) {
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/* If we have a cold block with fallthrough to a warm block, add */
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/* an explicit jump instead of fallthrough */
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for (basicblock *b = entry; b != NULL; b = b->b_next) {
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if (b->b_cold && !b->b_nofallthrough && b->b_next && b->b_next->b_warm) {
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if (b->b_cold && BB_HAS_FALLTHROUGH(b) && b->b_next && b->b_next->b_warm) {
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basicblock *explicit_jump = compiler_new_block(c);
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if (explicit_jump == NULL) {
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return -1;
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@ -7460,7 +7474,6 @@ push_cold_blocks_to_end(struct compiler *c, basicblock *entry, int code_flags) {
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basicblock_add_jump(explicit_jump, JUMP, -1, 0, 0, 0, b->b_next);
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explicit_jump->b_cold = 1;
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explicit_jump->b_nofallthrough = 1;
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explicit_jump->b_next = b->b_next;
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b->b_next = explicit_jump;
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}
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@ -7953,7 +7966,7 @@ scan_block_for_local(int target, basicblock *b, bool unsafe_to_start,
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if (unsafe) {
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// unsafe at end of this block,
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// so unsafe at start of next blocks
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if (b->b_next && !b->b_nofallthrough) {
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if (b->b_next && BB_HAS_FALLTHROUGH(b)) {
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MAYBE_PUSH(b->b_next);
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}
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if (b->b_iused > 0) {
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@ -8281,9 +8294,10 @@ dump_instr(struct instr *i)
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static void
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dump_basicblock(const basicblock *b)
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{
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const char *b_return = b->b_return ? "return " : "";
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const char *b_return = basicblock_returns(b) ? "return " : "";
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fprintf(stderr, "[%d %d %d %p] used: %d, depth: %d, offset: %d %s\n",
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b->b_cold, b->b_warm, b->b_nofallthrough, b, b->b_iused, b->b_startdepth, b->b_offset, b_return);
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b->b_cold, b->b_warm, BB_NO_FALLTHROUGH(b), b, b->b_iused,
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b->b_startdepth, b->b_offset, b_return);
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if (b->b_instr) {
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int i;
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for (i = 0; i < b->b_iused; i++) {
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@ -8545,7 +8559,6 @@ remove_redundant_jumps(basicblock *entry) {
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b_last_instr->i_opcode == JUMP_NO_INTERRUPT) {
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if (b_last_instr->i_target == b->b_next) {
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assert(b->b_next->b_iused);
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b->b_nofallthrough = 0;
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b_last_instr->i_opcode = NOP;
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removed++;
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}
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@ -8572,7 +8585,7 @@ assemble(struct compiler *c, int addNone)
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}
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/* Make sure every block that falls off the end returns None. */
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if (!c->u->u_curblock->b_return) {
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if (!basicblock_returns(c->u->u_curblock)) {
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UNSET_LOC(c);
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if (addNone)
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ADDOP_LOAD_CONST(c, Py_None);
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@ -9064,7 +9077,6 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
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jump_if_true = nextop == POP_JUMP_IF_TRUE;
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if (is_true == jump_if_true) {
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bb->b_instr[i+1].i_opcode = JUMP;
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bb->b_nofallthrough = 1;
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}
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else {
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bb->b_instr[i+1].i_opcode = NOP;
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@ -9084,7 +9096,6 @@ optimize_basic_block(struct compiler *c, basicblock *bb, PyObject *consts)
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jump_if_true = nextop == JUMP_IF_TRUE_OR_POP;
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if (is_true == jump_if_true) {
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bb->b_instr[i+1].i_opcode = JUMP;
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bb->b_nofallthrough = 1;
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}
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else {
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inst->i_opcode = NOP;
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@ -9273,7 +9284,7 @@ extend_block(basicblock *bb) {
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last->i_opcode != JUMP_BACKWARD) {
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return 0;
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}
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if (last->i_target->b_exit && last->i_target->b_iused <= MAX_COPY_SIZE) {
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if (basicblock_exits_scope(last->i_target) && last->i_target->b_iused <= MAX_COPY_SIZE) {
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basicblock *to_copy = last->i_target;
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last->i_opcode = NOP;
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for (int i = 0; i < to_copy->b_iused; i++) {
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@ -9283,7 +9294,6 @@ extend_block(basicblock *bb) {
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}
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bb->b_instr[index] = to_copy->b_instr[i];
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}
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bb->b_exit = 1;
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}
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return 0;
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}
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@ -9341,34 +9351,21 @@ normalize_basic_block(basicblock *bb) {
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/* Mark blocks as exit and/or nofallthrough.
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Raise SystemError if CFG is malformed. */
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for (int i = 0; i < bb->b_iused; i++) {
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assert(!IS_ASSEMBLER_OPCODE(bb->b_instr[i].i_opcode));
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switch(bb->b_instr[i].i_opcode) {
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case RETURN_VALUE:
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case RAISE_VARARGS:
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case RERAISE:
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bb->b_exit = 1;
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bb->b_nofallthrough = 1;
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break;
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case JUMP:
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case JUMP_NO_INTERRUPT:
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bb->b_nofallthrough = 1;
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/* fall through */
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case POP_JUMP_IF_NOT_NONE:
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case POP_JUMP_IF_NONE:
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case POP_JUMP_IF_FALSE:
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case POP_JUMP_IF_TRUE:
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case JUMP_IF_FALSE_OR_POP:
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case JUMP_IF_TRUE_OR_POP:
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case FOR_ITER:
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if (i != bb->b_iused-1) {
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PyErr_SetString(PyExc_SystemError, "malformed control flow graph.");
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return -1;
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}
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/* Skip over empty basic blocks. */
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while (bb->b_instr[i].i_target->b_iused == 0) {
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bb->b_instr[i].i_target = bb->b_instr[i].i_target->b_next;
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}
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int opcode = bb->b_instr[i].i_opcode;
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assert(!IS_ASSEMBLER_OPCODE(opcode));
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int is_jump = IS_JUMP_OPCODE(opcode);
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int is_exit = IS_SCOPE_EXIT_OPCODE(opcode);
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if (is_exit || is_jump) {
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if (i != bb->b_iused-1) {
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PyErr_SetString(PyExc_SystemError, "malformed control flow graph.");
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return -1;
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}
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}
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if (is_jump) {
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/* Skip over empty basic blocks. */
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while (bb->b_instr[i].i_target->b_iused == 0) {
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bb->b_instr[i].i_target = bb->b_instr[i].i_target->b_next;
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}
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}
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}
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return 0;
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@ -9386,7 +9383,7 @@ mark_reachable(struct assembler *a) {
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while (sp > stack) {
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basicblock *b = *(--sp);
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b->b_visited = 1;
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if (b->b_next && !b->b_nofallthrough) {
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if (b->b_next && BB_HAS_FALLTHROUGH(b)) {
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if (!b->b_next->b_visited) {
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assert(b->b_next->b_predecessors == 0);
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*sp++ = b->b_next;
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@ -9475,7 +9472,7 @@ propagate_line_numbers(struct assembler *a) {
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COPY_INSTR_LOC(b->b_instr[i], prev_instr);
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}
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}
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if (!b->b_nofallthrough && b->b_next->b_predecessors == 1) {
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if (BB_HAS_FALLTHROUGH(b) && b->b_next->b_predecessors == 1) {
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assert(b->b_next->b_iused);
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if (b->b_next->b_instr[0].i_lineno < 0) {
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COPY_INSTR_LOC(prev_instr, b->b_next->b_instr[0]);
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@ -9523,7 +9520,6 @@ optimize_cfg(struct compiler *c, struct assembler *a, PyObject *consts)
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for (basicblock *b = a->a_entry; b != NULL; b = b->b_next) {
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if (b->b_predecessors == 0) {
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b->b_iused = 0;
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b->b_nofallthrough = 0;
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}
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}
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eliminate_empty_basic_blocks(a->a_entry);
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@ -9563,7 +9559,7 @@ trim_unused_consts(struct assembler *a, PyObject *consts)
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static inline int
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is_exit_without_lineno(basicblock *b) {
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if (!b->b_exit) {
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if (!basicblock_exits_scope(b)) {
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return 0;
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}
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for (int i = 0; i < b->b_iused; i++) {
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@ -9614,7 +9610,7 @@ duplicate_exits_without_lineno(struct compiler *c)
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/* Any remaining reachable exit blocks without line number can only be reached by
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* fall through, and thus can only have a single predecessor */
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for (basicblock *b = c->u->u_blocks; b != NULL; b = b->b_list) {
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if (!b->b_nofallthrough && b->b_next && b->b_iused > 0) {
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||||
if (BB_HAS_FALLTHROUGH(b) && b->b_next && b->b_iused > 0) {
|
||||
if (is_exit_without_lineno(b->b_next)) {
|
||||
assert(b->b_next->b_iused > 0);
|
||||
COPY_INSTR_LOC(b->b_instr[b->b_iused-1], b->b_next->b_instr[0]);
|
||||
|
|
Loading…
Reference in New Issue