Exemple #1
0
/*
 * mono_local_cprop:
 *
 *  A combined local copy and constant propagation pass.
 */
void
mono_local_cprop (MonoCompile *cfg)
{
	MonoBasicBlock *bb;
	MonoInst **defs;
	gint32 *def_index;
	int max;

restart:

	max = cfg->next_vreg;
	defs = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * (cfg->next_vreg + 1));
	def_index = mono_mempool_alloc (cfg->mempool, sizeof (guint32) * (cfg->next_vreg + 1));

	for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
		MonoInst *ins;
		int ins_index;
		int last_call_index;

		/* Manually init the defs entries used by the bblock */
		MONO_BB_FOR_EACH_INS (bb, ins) {
			int sregs [MONO_MAX_SRC_REGS];
			int num_sregs, i;

			if ((ins->dreg != -1) && (ins->dreg < max)) {
				defs [ins->dreg] = NULL;
#if SIZEOF_REGISTER == 4
				defs [ins->dreg + 1] = NULL;
#endif
			}

			num_sregs = mono_inst_get_src_registers (ins, sregs);
			for (i = 0; i < num_sregs; ++i) {
				int sreg = sregs [i];
				if (sreg < max) {
					defs [sreg] = NULL;
#if SIZEOF_REGISTER == 4
					defs [sreg + 1] = NULL;
#endif
				}
			}
		}

		ins_index = 0;
		last_call_index = -1;
		MONO_BB_FOR_EACH_INS (bb, ins) {
			const char *spec = INS_INFO (ins->opcode);
			int regtype, srcindex, sreg;
			int num_sregs;
			int sregs [MONO_MAX_SRC_REGS];

			if (ins->opcode == OP_NOP) {
				MONO_DELETE_INS (bb, ins);
				continue;
			}

			g_assert (ins->opcode > MONO_CEE_LAST);

			/* FIXME: Optimize this */
			if (ins->opcode == OP_LDADDR) {
				MonoInst *var = ins->inst_p0;

				defs [var->dreg] = NULL;
				/*
				if (!MONO_TYPE_ISSTRUCT (var->inst_vtype))
					break;
				*/
			}

			if (MONO_IS_STORE_MEMBASE (ins)) {
				sreg = ins->dreg;
				regtype = 'i';

				if ((regtype == 'i') && (sreg != -1) && defs [sreg]) {
					MonoInst *def = defs [sreg];

					if ((def->opcode == OP_MOVE) && (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) && !vreg_is_volatile (cfg, def->sreg1)) {
						int vreg = def->sreg1;
						if (cfg->verbose_level > 2) printf ("CCOPY: R%d -> R%d\n", sreg, vreg);
						ins->dreg = vreg;
					}
				}
			}

			num_sregs = mono_inst_get_src_registers (ins, sregs);
			for (srcindex = 0; srcindex < num_sregs; ++srcindex) {
				MonoInst *def;
				int nregs;

				nregs = mono_inst_get_src_registers (ins, sregs);

				regtype = spec [MONO_INST_SRC1 + srcindex];
				sreg = sregs [srcindex];

				if ((regtype == ' ') || (sreg == -1) || (!defs [sreg]))
					continue;

				def = defs [sreg];

				/* Copy propagation */
				/* 
				 * The first check makes sure the source of the copy did not change since 
				 * the copy was made.
				 * The second check avoids volatile variables.
				 * The third check avoids copy propagating local vregs through a call, 
				 * since the lvreg will be spilled 
				 * The fourth check avoids copy propagating a vreg in cases where
				 * it would be eliminated anyway by reverse copy propagation later,
				 * because propagating it would create another use for it, thus making 
				 * it impossible to use reverse copy propagation.
				 */
				/* Enabling this for floats trips up the fp stack */
				/* 
				 * Enabling this for floats on amd64 seems to cause a failure in 
				 * basic-math.cs, most likely because it gets rid of some r8->r4 
				 * conversions.
				 */
				if (MONO_IS_MOVE (def) &&
					(!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) &&
					!vreg_is_volatile (cfg, def->sreg1) &&
					/* This avoids propagating local vregs across calls */
					((get_vreg_to_inst (cfg, def->sreg1) || !defs [def->sreg1] || (def_index [def->sreg1] >= last_call_index) || (def->opcode == OP_VMOVE))) &&
					!(defs [def->sreg1] && mono_inst_next (defs [def->sreg1], FILTER_IL_SEQ_POINT) == def) &&
					(!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE)) &&
					(def->opcode != OP_FMOVE)) {
					int vreg = def->sreg1;

					if (cfg->verbose_level > 2) printf ("CCOPY/2: R%d -> R%d\n", sreg, vreg);
					sregs [srcindex] = vreg;
					mono_inst_set_src_registers (ins, sregs);

					/* Allow further iterations */
					srcindex = -1;
					continue;
				}

				/* Constant propagation */
				/* FIXME: Make is_inst_imm a macro */
				/* FIXME: Make is_inst_imm take an opcode argument */
				/* is_inst_imm is only needed for binops */
				if ((((def->opcode == OP_ICONST) || ((sizeof (gpointer) == 8) && (def->opcode == OP_I8CONST))) &&
					 (((srcindex == 0) && (ins->sreg2 == -1)) || mono_arch_is_inst_imm (def->inst_c0))) || 
					(!MONO_ARCH_USE_FPSTACK && (def->opcode == OP_R8CONST))) {
					guint32 opcode2;

					/* srcindex == 1 -> binop, ins->sreg2 == -1 -> unop */
					if ((srcindex == 1) && (ins->sreg1 != -1) && defs [ins->sreg1] && (defs [ins->sreg1]->opcode == OP_ICONST) && defs [ins->sreg2]) {
						/* Both arguments are constants, perform cfold */
						mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
					} else if ((srcindex == 0) && (ins->sreg2 != -1) && defs [ins->sreg2]) {
						/* Arg 1 is constant, swap arguments if possible */
						int opcode = ins->opcode;
						mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
						if (ins->opcode != opcode) {
							/* Allow further iterations */
							srcindex = -1;
							continue;
						}
					} else if ((srcindex == 0) && (ins->sreg2 == -1)) {
						/* Constant unop, perform cfold */
						mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], NULL, TRUE);
					}

					opcode2 = mono_op_to_op_imm (ins->opcode);
					if ((opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0) && ((srcindex == 1) || (ins->sreg2 == -1))) {
						ins->opcode = opcode2;
						if ((def->opcode == OP_I8CONST) && (sizeof (gpointer) == 4)) {
							ins->inst_ls_word = def->inst_ls_word;
							ins->inst_ms_word = def->inst_ms_word;
						} else {
							ins->inst_imm = def->inst_c0;
						}
						sregs [srcindex] = -1;
						mono_inst_set_src_registers (ins, sregs);

						if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
							((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;

						/* Allow further iterations */
						srcindex = -1;
						continue;
					}
					else {
						/* Special cases */
#if defined(TARGET_X86) || defined(TARGET_AMD64)
						if ((ins->opcode == OP_X86_LEA) && (srcindex == 1)) {
#if SIZEOF_REGISTER == 8
							/* FIXME: Use OP_PADD_IMM when the new JIT is done */
							ins->opcode = OP_LADD_IMM;
#else
							ins->opcode = OP_ADD_IMM;
#endif
							ins->inst_imm += def->inst_c0 << ins->backend.shift_amount;
							ins->sreg2 = -1;
						}
#endif
						opcode2 = mono_load_membase_to_load_mem (ins->opcode);
						if ((srcindex == 0) && (opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0)) {
							ins->opcode = opcode2;
							ins->inst_imm = def->inst_c0 + ins->inst_offset;
							ins->sreg1 = -1;
						}
					}
				}
				else if (((def->opcode == OP_ADD_IMM) || (def->opcode == OP_LADD_IMM)) && (MONO_IS_LOAD_MEMBASE (ins) || MONO_ARCH_IS_OP_MEMBASE (ins->opcode))) {
					/* ADD_IMM is created by spill_global_vars */
					/* 
					 * We have to guarantee that def->sreg1 haven't changed since def->dreg
					 * was defined. cfg->frame_reg is assumed to remain constant.
					 */
					if ((def->sreg1 == cfg->frame_reg) || ((def->next == ins) && (def->dreg != def->sreg1))) {
						ins->inst_basereg = def->sreg1;
						ins->inst_offset += def->inst_imm;
					}
				} else if ((ins->opcode == OP_ISUB_IMM) && (def->opcode == OP_IADD_IMM) && (def->next == ins) && (def->dreg != def->sreg1)) {
					ins->sreg1 = def->sreg1;
					ins->inst_imm -= def->inst_imm;
				} else if ((ins->opcode == OP_IADD_IMM) && (def->opcode == OP_ISUB_IMM) && (def->next == ins) && (def->dreg != def->sreg1)) {
					ins->sreg1 = def->sreg1;
					ins->inst_imm -= def->inst_imm;
				} else if (ins->opcode == OP_STOREI1_MEMBASE_REG &&
						   (def->opcode == OP_ICONV_TO_U1 || def->opcode == OP_ICONV_TO_I1 || def->opcode == OP_SEXT_I4 || (SIZEOF_REGISTER == 8 && def->opcode == OP_LCONV_TO_U1)) &&
						   (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
					/* Avoid needless sign extension */
					ins->sreg1 = def->sreg1;
				} else if (ins->opcode == OP_STOREI2_MEMBASE_REG &&
						   (def->opcode == OP_ICONV_TO_U2 || def->opcode == OP_ICONV_TO_I2 || def->opcode == OP_SEXT_I4 || (SIZEOF_REGISTER == 8 && def->opcode == OP_LCONV_TO_I2)) &&
						   (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
					/* Avoid needless sign extension */
					ins->sreg1 = def->sreg1;
				}
			}

			/* Do strength reduction here */
			/* FIXME: Add long/float */
			switch (ins->opcode) {
			case OP_MOVE:
			case OP_XMOVE:
				if (ins->dreg == ins->sreg1) {
					MONO_DELETE_INS (bb, ins);
					spec = INS_INFO (ins->opcode);
				}
				break;
			case OP_ADD_IMM:
			case OP_IADD_IMM:
			case OP_SUB_IMM:
			case OP_ISUB_IMM:
#if SIZEOF_REGISTER == 8
			case OP_LADD_IMM:
			case OP_LSUB_IMM:
#endif
				if (ins->inst_imm == 0) {
					ins->opcode = OP_MOVE;
					spec = INS_INFO (ins->opcode);
				}
				break;
			case OP_MUL_IMM:
			case OP_IMUL_IMM:
#if SIZEOF_REGISTER == 8
			case OP_LMUL_IMM:
#endif
				if (ins->inst_imm == 0) {
					ins->opcode = (ins->opcode == OP_LMUL_IMM) ? OP_I8CONST : OP_ICONST;
					ins->inst_c0 = 0;
					ins->sreg1 = -1;
				} else if (ins->inst_imm == 1) {
					ins->opcode = OP_MOVE;
				} else if ((ins->opcode == OP_IMUL_IMM) && (ins->inst_imm == -1)) {
					ins->opcode = OP_INEG;
				} else if ((ins->opcode == OP_LMUL_IMM) && (ins->inst_imm == -1)) {
					ins->opcode = OP_LNEG;
				} else {
					int power2 = mono_is_power_of_two (ins->inst_imm);
					if (power2 >= 0) {
						ins->opcode = (ins->opcode == OP_MUL_IMM) ? OP_SHL_IMM : ((ins->opcode == OP_LMUL_IMM) ? OP_LSHL_IMM : OP_ISHL_IMM);
						ins->inst_imm = power2;
					}
				}
				spec = INS_INFO (ins->opcode);
				break;
			case OP_IREM_UN_IMM:
			case OP_IDIV_UN_IMM: {
				int c = ins->inst_imm;
				int power2 = mono_is_power_of_two (c);

				if (power2 >= 0) {
					if (ins->opcode == OP_IREM_UN_IMM) {
						ins->opcode = OP_IAND_IMM;
						ins->sreg2 = -1;
						ins->inst_imm = (1 << power2) - 1;
					} else if (ins->opcode == OP_IDIV_UN_IMM) {
						ins->opcode = OP_ISHR_UN_IMM;
						ins->sreg2 = -1;
						ins->inst_imm = power2;
					}
				}
				spec = INS_INFO (ins->opcode);
				break;
			}
			case OP_IDIV_IMM: {
				int c = ins->inst_imm;
				int power2 = mono_is_power_of_two (c);
				MonoInst *tmp1, *tmp2, *tmp3, *tmp4;

				/* FIXME: Move this elsewhere cause its hard to implement it here */
				if (power2 == 1) {
					int r1 = mono_alloc_ireg (cfg);

					NEW_BIALU_IMM (cfg, tmp1, OP_ISHR_UN_IMM, r1, ins->sreg1, 31);
					mono_bblock_insert_after_ins (bb, ins, tmp1);
					NEW_BIALU (cfg, tmp2, OP_IADD, r1, r1, ins->sreg1);
					mono_bblock_insert_after_ins (bb, tmp1, tmp2);
					NEW_BIALU_IMM (cfg, tmp3, OP_ISHR_IMM, ins->dreg, r1, 1);
					mono_bblock_insert_after_ins (bb, tmp2, tmp3);

					NULLIFY_INS (ins);

					// We allocated a new vreg, so need to restart
					goto restart;
				} else if (power2 > 0) {
					int r1 = mono_alloc_ireg (cfg);

					NEW_BIALU_IMM (cfg, tmp1, OP_ISHR_IMM, r1, ins->sreg1, 31);
					mono_bblock_insert_after_ins (bb, ins, tmp1);
					NEW_BIALU_IMM (cfg, tmp2, OP_ISHR_UN_IMM, r1, r1, (32 - power2));
					mono_bblock_insert_after_ins (bb, tmp1, tmp2);
					NEW_BIALU (cfg, tmp3, OP_IADD, r1, r1, ins->sreg1);
					mono_bblock_insert_after_ins (bb, tmp2, tmp3);
					NEW_BIALU_IMM (cfg, tmp4, OP_ISHR_IMM, ins->dreg, r1, power2);
					mono_bblock_insert_after_ins (bb, tmp3, tmp4);

					NULLIFY_INS (ins);

					// We allocated a new vreg, so need to restart
					goto restart;
				}
				break;
			}
			}
			
			if (spec [MONO_INST_DEST] != ' ') {
				MonoInst *def = defs [ins->dreg];

				if (def && (def->opcode == OP_ADD_IMM) && (def->sreg1 == cfg->frame_reg) && (MONO_IS_STORE_MEMBASE (ins))) {
					/* ADD_IMM is created by spill_global_vars */
					/* cfg->frame_reg is assumed to remain constant */
					ins->inst_destbasereg = def->sreg1;
					ins->inst_offset += def->inst_imm;
				}
			}
			
			if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins) && !vreg_is_volatile (cfg, ins->dreg)) {
				defs [ins->dreg] = ins;
				def_index [ins->dreg] = ins_index;
			}

			if (MONO_IS_CALL (ins))
				last_call_index = ins_index;

			ins_index ++;
		}
	}
Exemple #2
0
/*
 * Process a BB removing bounds checks from array accesses.
 * It does the following (in sequence):
 * - Get the BB entry condition
 * - Add its relations to the relation graph in the evaluation area
 * - Process all the MonoInst trees in the BB
 * - Recursively process all the children BBs in the dominator tree
 * - Remove the relations previously added to the relation graph
 *
 * bb: the BB that must be processed
 * area: the current evaluation area (it contains the relation graph and
 *       memory for all the evaluation contexts is already allocated)
 */
static void
process_block (MonoCompile *cfg, MonoBasicBlock *bb, MonoVariableRelationsEvaluationArea *area) {
	int inst_index;
	MonoInst *ins;
	MonoAdditionalVariableRelationsForBB additional_relations;
	GSList *dominated_bb, *l;
	GSList *check_relations = NULL;
	
	if (TRACE_ABC_REMOVAL) {
		printf ("\nProcessing block %d [dfn %d]...\n", bb->block_num, bb->dfn);
	}

	if (bb->region != -1)
		return;

	get_relations_from_previous_bb (area, bb, &additional_relations);
	if (TRACE_ABC_REMOVAL) {
		if (additional_relations.relation1.relation.relation != MONO_ANY_RELATION) {
			printf ("Adding relation 1 on variable %d: ", additional_relations.relation1.variable);
			print_summarized_value_relation (&(additional_relations.relation1.relation));
			printf ("\n");
		}
		if (additional_relations.relation2.relation.relation != MONO_ANY_RELATION) {
			printf ("Adding relation 2 on variable %d: ", additional_relations.relation2.variable);
			print_summarized_value_relation (&(additional_relations.relation2.relation));
			printf ("\n");
		}
	}
	apply_change_to_evaluation_area (area, &(additional_relations.relation1));
	apply_change_to_evaluation_area (area, &(additional_relations.relation2));

	inst_index = 0;
	for (ins = bb->code; ins; ins = ins->next) {
		MonoAdditionalVariableRelation *rel;
		int array_var, index_var;

		if (TRACE_ABC_REMOVAL) {
			printf ("Processing instruction %d\n", inst_index);
			inst_index++;
		}

		if (ins->opcode == OP_BOUNDS_CHECK) { /* Handle OP_LDELEMA2D, too */
			if (TRACE_ABC_REMOVAL) {
				printf ("Attempting check removal...\n");
			}

			array_var = ins->sreg1;
			index_var = ins->sreg2;
		
			remove_abc_from_inst (ins, area);

			/* We can derive additional relations from the bounds check */
			if (ins->opcode != OP_NOP) {
				rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
				rel->variable = index_var;
				rel->relation.relation = MONO_LT_RELATION;
				rel->relation.related_value.type = MONO_VARIABLE_SUMMARIZED_VALUE;
				rel->relation.related_value.value.variable.variable = array_var;
				rel->relation.related_value.value.variable.delta = 0;

				apply_change_to_evaluation_area (area, rel);

				check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);

				rel = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoAdditionalVariableRelation));
				rel->variable = index_var;
				rel->relation.relation = MONO_GE_RELATION;
				rel->relation.related_value.type = MONO_CONSTANT_SUMMARIZED_VALUE;
				rel->relation.related_value.value.constant.value = 0;

				apply_change_to_evaluation_area (area, rel);

				check_relations = g_slist_append_mempool (cfg->mempool, check_relations, rel);
			}
		}

		if (ins->opcode == OP_CHECK_THIS) {
			if (eval_non_null (area, ins->sreg1)) {
				if (REPORT_ABC_REMOVAL)
					printf ("ARRAY-ACCESS: removed check_this instruction.\n");
				NULLIFY_INS (ins);
			}
		}

		if (ins->opcode == OP_NOT_NULL)
			add_non_null (area, cfg, ins->sreg1, &check_relations);

		/* 
		 * This doesn't work because LLVM can move the non-faulting loads before the faulting
		 * ones (test_0_llvm_moving_faulting_loads ()).
		 * FIXME: This also doesn't work because abcrem equates an array with its length,
		 * so a = new int [100] implies a != null, but a = new int [0] doesn't.
		 */
#if 0
		/*
		 * Eliminate MONO_INST_FAULT flags if possible.
		 */
		if (COMPILE_LLVM (cfg) && (ins->opcode == OP_LDLEN ||
								   ins->opcode == OP_BOUNDS_CHECK ||
								   ins->opcode == OP_STRLEN ||
								   (MONO_IS_LOAD_MEMBASE (ins) && (ins->flags & MONO_INST_FAULT)) ||
								   (MONO_IS_STORE_MEMBASE (ins) && (ins->flags & MONO_INST_FAULT)))) {
			int reg;

			if (MONO_IS_STORE_MEMBASE (ins))
				reg = ins->inst_destbasereg;
			else if (MONO_IS_LOAD_MEMBASE (ins))
				reg = ins->inst_basereg;
			else
				reg = ins->sreg1;

			if (eval_non_null (area, reg)) {
				if (REPORT_ABC_REMOVAL)
					printf ("ARRAY-ACCESS: removed MONO_INST_FAULT flag.\n");
				ins->flags &= ~MONO_INST_FAULT;
			} else {
				add_non_null (area, cfg, reg, &check_relations);
			}
		}
#endif
	}	
	
	if (TRACE_ABC_REMOVAL) {
		printf ("Processing block %d [dfn %d] done.\n", bb->block_num, bb->dfn);
	}
	
	for (dominated_bb = bb->dominated; dominated_bb != NULL; dominated_bb = dominated_bb->next) {
		process_block (cfg, (MonoBasicBlock*) (dominated_bb->data), area);
	}

	for (l = check_relations; l; l = l->next)
		remove_change_from_evaluation_area (l->data);
	
	remove_change_from_evaluation_area (&(additional_relations.relation1));
	remove_change_from_evaluation_area (&(additional_relations.relation2));
}