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Makefile.in (OBJS-common): Add tree-ssa-uncprop.o.
* Makefile.in (OBJS-common): Add tree-ssa-uncprop.o. (tree-ssa-uncprop.o): Add dependencies. * tree-cfg.c (remove_useless_stmts_bb, remove_useless_stmts): Remove. * tree-flow.h (remove_useless_stmts): Remove prototype. * tree-outof-ssa.c (rewrite_out_of_ssa): Remove call to remove_useless_stmts. * timevar.def (TV_TREE_SSA_UNCPROP): New timevar. * tree-optimize.c (init_tree_optimization_passes): Add uncprop pass. * tree-pass.h (pass_uncprop): Declare. * tree-ssa-uncprop.c: New file. From-SVN: r98066
This commit is contained in:
parent
6dab073ba7
commit
fef0657c25
@ -1,3 +1,16 @@
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2005-04-12 Jeff Law <law@redhat.com>
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* Makefile.in (OBJS-common): Add tree-ssa-uncprop.o.
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(tree-ssa-uncprop.o): Add dependencies.
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* tree-cfg.c (remove_useless_stmts_bb, remove_useless_stmts): Remove.
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* tree-flow.h (remove_useless_stmts): Remove prototype.
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* tree-outof-ssa.c (rewrite_out_of_ssa): Remove call to
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remove_useless_stmts.
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* timevar.def (TV_TREE_SSA_UNCPROP): New timevar.
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* tree-optimize.c (init_tree_optimization_passes): Add uncprop pass.
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* tree-pass.h (pass_uncprop): Declare.
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* tree-ssa-uncprop.c: New file.
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2005-04-12 James E. Wilson <wilson@specifixinc.com>
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PR target/20670
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@ -924,7 +924,7 @@ OBJS-common = \
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tree-chrec.o tree-scalar-evolution.o tree-data-ref.o \
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tree-cfg.o tree-dfa.o tree-eh.o tree-ssa.o tree-optimize.o tree-gimple.o \
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gimplify.o tree-pretty-print.o tree-into-ssa.o \
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tree-outof-ssa.o tree-ssa-ccp.o tree-vn.o \
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tree-outof-ssa.o tree-ssa-ccp.o tree-vn.o tree-ssa-uncprop.o \
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tree-ssa-dce.o tree-ssa-copy.o tree-nrv.o tree-ssa-copyrename.o \
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tree-ssa-pre.o tree-ssa-live.o tree-ssa-operands.o tree-ssa-alias.o \
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tree-ssa-phiopt.o tree-ssa-forwprop.o tree-nested.o tree-ssa-dse.o \
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@ -1666,6 +1666,11 @@ tree-ssa-dom.o : tree-ssa-dom.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
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errors.h function.h $(TIMEVAR_H) $(TM_H) coretypes.h $(TREE_DUMP_H) \
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$(BASIC_BLOCK_H) domwalk.h real.h tree-pass.h $(FLAGS_H) langhooks.h \
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tree-ssa-propagate.h cfgloop.h
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tree-ssa-uncprop.o : tree-ssa-uncprop.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
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$(RTL_H) $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) output.h diagnostic.h \
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errors.h function.h $(TIMEVAR_H) $(TM_H) coretypes.h $(TREE_DUMP_H) \
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$(BASIC_BLOCK_H) domwalk.h real.h tree-pass.h $(FLAGS_H) langhooks.h \
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tree-ssa-propagate.h cfgloop.h
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tree-ssa-threadupdate.o : tree-ssa-threadupdate.c $(TREE_FLOW_H) $(CONFIG_H) \
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$(SYSTEM_H) $(RTL_H) $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) output.h \
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diagnostic.h errors.h function.h $(TM_H) coretypes.h $(TREE_DUMP_H) \
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@ -103,6 +103,7 @@ DEFTIMEVAR (TV_TREE_LOOP_IVOPTS , "tree iv optimization")
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DEFTIMEVAR (TV_TREE_LOOP_INIT , "tree loop init")
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DEFTIMEVAR (TV_TREE_LOOP_FINI , "tree loop fini")
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DEFTIMEVAR (TV_TREE_CH , "tree copy headers")
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DEFTIMEVAR (TV_TREE_SSA_UNCPROP , "tree SSA uncprop")
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DEFTIMEVAR (TV_TREE_SSA_TO_NORMAL , "tree SSA to normal")
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DEFTIMEVAR (TV_TREE_NRV , "tree NRV optimization")
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DEFTIMEVAR (TV_TREE_COPY_RENAME , "tree rename SSA copies")
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121
gcc/tree-cfg.c
121
gcc/tree-cfg.c
@ -1896,127 +1896,6 @@ struct tree_opt_pass pass_remove_useless_stmts =
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0 /* letter */
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};
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/* Remove obviously useless statements in basic block BB. */
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static void
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cfg_remove_useless_stmts_bb (basic_block bb)
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{
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block_stmt_iterator bsi;
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tree stmt = NULL_TREE;
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tree cond, var = NULL_TREE, val = NULL_TREE;
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struct var_ann_d *ann;
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/* Check whether we come here from a condition, and if so, get the
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condition. */
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if (!single_pred_p (bb)
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|| !(single_pred_edge (bb)->flags
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& (EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
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return;
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cond = COND_EXPR_COND (last_stmt (single_pred (bb)));
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if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
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{
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var = cond;
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val = (single_pred_edge (bb)->flags & EDGE_FALSE_VALUE
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? boolean_false_node : boolean_true_node);
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}
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else if (TREE_CODE (cond) == TRUTH_NOT_EXPR
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&& (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
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|| TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL))
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{
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var = TREE_OPERAND (cond, 0);
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val = (single_pred_edge (bb)->flags & EDGE_FALSE_VALUE
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? boolean_true_node : boolean_false_node);
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}
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else
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{
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if (single_pred_edge (bb)->flags & EDGE_FALSE_VALUE)
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cond = invert_truthvalue (cond);
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if (TREE_CODE (cond) == EQ_EXPR
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&& (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
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|| TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
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&& (TREE_CODE (TREE_OPERAND (cond, 1)) == VAR_DECL
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|| TREE_CODE (TREE_OPERAND (cond, 1)) == PARM_DECL
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|| TREE_CONSTANT (TREE_OPERAND (cond, 1))))
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{
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var = TREE_OPERAND (cond, 0);
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val = TREE_OPERAND (cond, 1);
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}
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else
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return;
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}
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/* Only work for normal local variables. */
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ann = var_ann (var);
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if (!ann
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|| ann->may_aliases
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|| TREE_ADDRESSABLE (var))
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return;
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if (! TREE_CONSTANT (val))
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{
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ann = var_ann (val);
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if (!ann
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|| ann->may_aliases
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|| TREE_ADDRESSABLE (val))
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return;
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}
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/* Ignore floating point variables, since comparison behaves weird for
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them. */
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if (FLOAT_TYPE_P (TREE_TYPE (var)))
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return;
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for (bsi = bsi_start (bb); !bsi_end_p (bsi);)
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{
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stmt = bsi_stmt (bsi);
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/* If the THEN/ELSE clause merely assigns a value to a variable/parameter
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which is already known to contain that value, then remove the useless
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THEN/ELSE clause. */
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if (TREE_CODE (stmt) == MODIFY_EXPR
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&& TREE_OPERAND (stmt, 0) == var
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&& operand_equal_p (val, TREE_OPERAND (stmt, 1), 0))
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{
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bsi_remove (&bsi);
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continue;
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}
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/* Invalidate the var if we encounter something that could modify it.
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Likewise for the value it was previously set to. Note that we only
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consider values that are either a VAR_DECL or PARM_DECL so we
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can test for conflict very simply. */
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if (TREE_CODE (stmt) == ASM_EXPR
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|| (TREE_CODE (stmt) == MODIFY_EXPR
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&& (TREE_OPERAND (stmt, 0) == var
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|| TREE_OPERAND (stmt, 0) == val)))
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return;
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bsi_next (&bsi);
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}
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}
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/* A CFG-aware version of remove_useless_stmts. */
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void
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cfg_remove_useless_stmts (void)
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{
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basic_block bb;
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#ifdef ENABLE_CHECKING
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verify_flow_info ();
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#endif
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FOR_EACH_BB (bb)
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{
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cfg_remove_useless_stmts_bb (bb);
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}
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}
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/* Remove PHI nodes associated with basic block BB and all edges out of BB. */
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static void
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@ -522,7 +522,6 @@ extern tree last_stmt (basic_block);
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extern tree *last_stmt_ptr (basic_block);
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extern tree last_and_only_stmt (basic_block);
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extern edge find_taken_edge (basic_block, tree);
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extern void cfg_remove_useless_stmts (void);
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extern basic_block label_to_block_fn (struct function *, tree);
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#define label_to_block(t) (label_to_block_fn (cfun, t))
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extern void bsi_insert_on_edge (edge, tree);
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@ -407,6 +407,7 @@ init_tree_optimization_passes (void)
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NEXT_PASS (pass_phiopt);
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NEXT_PASS (pass_tail_calls);
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NEXT_PASS (pass_rename_ssa_copies);
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NEXT_PASS (pass_uncprop);
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NEXT_PASS (pass_del_ssa);
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NEXT_PASS (pass_nrv);
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NEXT_PASS (pass_remove_useless_vars);
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@ -2508,10 +2508,6 @@ rewrite_out_of_ssa (void)
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if (dump_file && (dump_flags & TDF_DETAILS))
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dump_tree_cfg (dump_file, dump_flags & ~TDF_DETAILS);
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/* Do some cleanups which reduce the amount of data the
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tree->rtl expanders deal with. */
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cfg_remove_useless_stmts ();
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/* Flush out flow graph and SSA data. */
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delete_var_map (map);
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@ -212,5 +212,6 @@ extern struct tree_opt_pass pass_store_ccp;
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extern struct tree_opt_pass pass_store_copy_prop;
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extern struct tree_opt_pass pass_vrp;
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extern struct tree_opt_pass pass_create_structure_vars;
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extern struct tree_opt_pass pass_uncprop;
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#endif /* GCC_TREE_PASS_H */
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614
gcc/tree-ssa-uncprop.c
Normal file
614
gcc/tree-ssa-uncprop.c
Normal file
@ -0,0 +1,614 @@
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/* Routines for discovering and unpropagating edge equivalences.
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Copyright (C) 2005 Free Software Foundation, Inc.
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This file is part of GCC.
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GCC is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GCC is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GCC; see the file COPYING. If not, write to
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the Free Software Foundation, 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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#include "config.h"
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#include "system.h"
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#include "coretypes.h"
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#include "tm.h"
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#include "tree.h"
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#include "flags.h"
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#include "rtl.h"
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#include "tm_p.h"
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#include "ggc.h"
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#include "basic-block.h"
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#include "output.h"
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#include "errors.h"
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#include "expr.h"
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#include "function.h"
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#include "diagnostic.h"
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#include "timevar.h"
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#include "tree-dump.h"
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#include "tree-flow.h"
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#include "domwalk.h"
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#include "real.h"
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#include "tree-pass.h"
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#include "tree-ssa-propagate.h"
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#include "langhooks.h"
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/* The basic structure describing an equivalency created by traversing
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an edge. Traversing the edge effectively means that we can assume
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that we've seen an assignment LHS = RHS. */
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struct edge_equivalency
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{
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tree rhs;
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tree lhs;
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};
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/* This routine finds and records edge equivalences for every edge
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in the CFG.
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When complete, each edge that creates an equivalency will have an
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EDGE_EQUIVALENCY structure hanging off the edge's AUX field.
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The caller is responsible for freeing the AUX fields. */
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static void
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associate_equivalences_with_edges (void)
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{
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basic_block bb;
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/* Walk over each block. If the block ends with a control statement,
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then it might create a useful equivalence. */
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FOR_EACH_BB (bb)
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{
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block_stmt_iterator bsi = bsi_last (bb);
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tree stmt;
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/* If the block does not end with a COND_EXPR or SWITCH_EXPR
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then there is nothing to do. */
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if (bsi_end_p (bsi))
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continue;
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stmt = bsi_stmt (bsi);
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if (!stmt)
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continue;
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/* A COND_EXPR may create an equivalency in a variety of different
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ways. */
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if (TREE_CODE (stmt) == COND_EXPR)
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{
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tree cond = COND_EXPR_COND (stmt);
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edge true_edge;
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edge false_edge;
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struct edge_equivalency *equivalency;
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extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
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/* If the conditional is a single variable 'X', record 'X = 1'
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for the true edge and 'X = 0' on the false edge. */
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if (TREE_CODE (cond) == SSA_NAME)
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{
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equivalency = xmalloc (sizeof (struct edge_equivalency));
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equivalency->rhs = constant_boolean_node (1, TREE_TYPE (cond));
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equivalency->lhs = cond;
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true_edge->aux = equivalency;
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equivalency = xmalloc (sizeof (struct edge_equivalency));
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equivalency->rhs = constant_boolean_node (0, TREE_TYPE (cond));
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equivalency->lhs = cond;
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false_edge->aux = equivalency;
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}
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/* Equality tests may create one or two equivalences. */
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else if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
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{
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tree op0 = TREE_OPERAND (cond, 0);
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tree op1 = TREE_OPERAND (cond, 1);
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/* Special case comparing booleans against a constant as we
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know the value of OP0 on both arms of the branch. i.e., we
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can record an equivalence for OP0 rather than COND. */
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if (TREE_CODE (op0) == SSA_NAME
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&& TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE
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&& is_gimple_min_invariant (op1))
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{
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if (TREE_CODE (cond) == EQ_EXPR)
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{
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equivalency = xmalloc (sizeof (struct edge_equivalency));
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equivalency->lhs = op0;
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equivalency->rhs = (integer_zerop (op1)
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? boolean_false_node
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: boolean_true_node);
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true_edge->aux = equivalency;
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equivalency = xmalloc (sizeof (struct edge_equivalency));
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equivalency->lhs = op0;
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equivalency->rhs = (integer_zerop (op1)
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? boolean_true_node
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: boolean_false_node);
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false_edge->aux = equivalency;
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}
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else
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{
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equivalency = xmalloc (sizeof (struct edge_equivalency));
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equivalency->lhs = op0;
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equivalency->rhs = (integer_zerop (op1)
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||||
? boolean_true_node
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||||
: boolean_false_node);
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true_edge->aux = equivalency;
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||||
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equivalency = xmalloc (sizeof (struct edge_equivalency));
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equivalency->lhs = op0;
|
||||
equivalency->rhs = (integer_zerop (op1)
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||||
? boolean_false_node
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||||
: boolean_true_node);
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||||
false_edge->aux = equivalency;
|
||||
}
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||||
}
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||||
|
||||
if (TREE_CODE (op0) == SSA_NAME
|
||||
&& (is_gimple_min_invariant (op1)
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||||
|| TREE_CODE (op1) == SSA_NAME))
|
||||
{
|
||||
/* For IEEE, -0.0 == 0.0, so we don't necessarily know
|
||||
the sign of a variable compared against zero. If
|
||||
we're honoring signed zeros, then we cannot record
|
||||
this value unless we know that the value is nonzero. */
|
||||
if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op0)))
|
||||
&& (TREE_CODE (op1) != REAL_CST
|
||||
|| REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (op1))))
|
||||
continue;
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||||
|
||||
equivalency = xmalloc (sizeof (struct edge_equivalency));
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equivalency->lhs = op0;
|
||||
equivalency->rhs = op1;
|
||||
if (TREE_CODE (cond) == EQ_EXPR)
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||||
true_edge->aux = equivalency;
|
||||
else
|
||||
false_edge->aux = equivalency;
|
||||
|
||||
}
|
||||
}
|
||||
|
||||
/* ??? TRUTH_NOT_EXPR can create an equivalence too. */
|
||||
}
|
||||
|
||||
/* For a SWITCH_EXPR, a case label which represents a single
|
||||
value and which is the only case label which reaches the
|
||||
target block creates an equivalence. */
|
||||
if (TREE_CODE (stmt) == SWITCH_EXPR)
|
||||
{
|
||||
tree cond = SWITCH_COND (stmt);
|
||||
|
||||
if (TREE_CODE (cond) == SSA_NAME)
|
||||
{
|
||||
tree labels = SWITCH_LABELS (stmt);
|
||||
int i, n_labels = TREE_VEC_LENGTH (labels);
|
||||
tree *info = xcalloc (n_basic_blocks, sizeof (tree));
|
||||
|
||||
/* Walk over the case label vector. Record blocks
|
||||
which are reached by a single case label which represents
|
||||
a single value. */
|
||||
for (i = 0; i < n_labels; i++)
|
||||
{
|
||||
tree label = TREE_VEC_ELT (labels, i);
|
||||
basic_block bb = label_to_block (CASE_LABEL (label));
|
||||
|
||||
|
||||
if (CASE_HIGH (label)
|
||||
|| !CASE_LOW (label)
|
||||
|| info[bb->index])
|
||||
info[bb->index] = error_mark_node;
|
||||
else
|
||||
info[bb->index] = label;
|
||||
}
|
||||
|
||||
/* Now walk over the blocks to determine which ones were
|
||||
marked as being reached by a useful case label. */
|
||||
for (i = 0; i < n_basic_blocks; i++)
|
||||
{
|
||||
tree node = info[i];
|
||||
|
||||
if (node != NULL
|
||||
&& node != error_mark_node)
|
||||
{
|
||||
tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node));
|
||||
struct edge_equivalency *equivalency;
|
||||
|
||||
/* Record an equivalency on the edge from BB to basic
|
||||
block I. */
|
||||
equivalency = xmalloc (sizeof (struct edge_equivalency));
|
||||
equivalency->rhs = x;
|
||||
equivalency->lhs = cond;
|
||||
find_edge (bb, BASIC_BLOCK (i))->aux = equivalency;
|
||||
}
|
||||
}
|
||||
free (info);
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
}
|
||||
|
||||
|
||||
/* Translating out of SSA sometimes requires inserting copies and
|
||||
constant initializations on edges to eliminate PHI nodes.
|
||||
|
||||
In some cases those copies and constant initializations are
|
||||
redundant because the target already has the value on the
|
||||
RHS of the assignment.
|
||||
|
||||
We previously tried to catch these cases after translating
|
||||
out of SSA form. However, that code often missed cases. Worse
|
||||
yet, the cases it missed were also often missed by the RTL
|
||||
optimizers. Thus the resulting code had redundant instructions.
|
||||
|
||||
This pass attempts to detect these situations before translating
|
||||
out of SSA form.
|
||||
|
||||
The key concept that this pass is built upon is that these
|
||||
redundant copies and constant initializations often occur
|
||||
due to constant/copy propagating equivalences resulting from
|
||||
COND_EXPRs and SWITCH_EXPRs.
|
||||
|
||||
We want to do those propagations as they can sometimes allow
|
||||
the SSA optimziers to do a better job. However, in the cases
|
||||
where such propagations do not result in further optimization,
|
||||
we would like to "undo" the propagation to avoid the redundant
|
||||
copies and constant initializations.
|
||||
|
||||
This pass works by first associating equivalences with edges in
|
||||
the CFG. For example, the edge leading from a SWITCH_EXPR to
|
||||
its associated CASE_LABEL will have an equivalency between
|
||||
SWITCH_COND and the value in the case label.
|
||||
|
||||
Once we have found the edge equivalences, we proceed to walk
|
||||
the CFG in dominator order. As we traverse edges we record
|
||||
equivalences associated with those edges we traverse.
|
||||
|
||||
When we encounter a PHI node, we walk its arguments to see if we
|
||||
have an equivalence for the PHI argument. If so, then we replace
|
||||
the argument.
|
||||
|
||||
Equivalences are looked up based on their value (think of it as
|
||||
the RHS of an assignment). A value may be an SSA_NAME or an
|
||||
invariant. We may have several SSA_NAMEs with the same value,
|
||||
so with each value we have a list of SSA_NAMEs that have the
|
||||
same value. */
|
||||
|
||||
/* As we enter each block we record the value for any edge equivalency
|
||||
leading to this block. If no such edge equivalency exists, then we
|
||||
record NULL. These equivalences are live until we leave the dominator
|
||||
subtree rooted at the block where we record the equivalency. */
|
||||
static varray_type equiv_stack;
|
||||
|
||||
/* Global hash table implementing a mapping from invariant values
|
||||
to a list of SSA_NAMEs which have the same value. We might be
|
||||
able to reuse tree-vn for this code. */
|
||||
static htab_t equiv;
|
||||
|
||||
/* Main structure for recording equivalences into our hash table. */
|
||||
struct equiv_hash_elt
|
||||
{
|
||||
/* The value/key of this entry. */
|
||||
tree value;
|
||||
|
||||
/* List of SSA_NAMEs which have the same value/key. */
|
||||
varray_type equivalences;
|
||||
};
|
||||
|
||||
static void uncprop_initialize_block (struct dom_walk_data *, basic_block);
|
||||
static void uncprop_finalize_block (struct dom_walk_data *, basic_block);
|
||||
static void uncprop_into_successor_phis (struct dom_walk_data *, basic_block);
|
||||
|
||||
/* Hashing and equality routines for the hash table. */
|
||||
|
||||
static hashval_t
|
||||
equiv_hash (const void *p)
|
||||
{
|
||||
tree value = ((struct equiv_hash_elt *)p)->value;
|
||||
return iterative_hash_expr (value, 0);
|
||||
}
|
||||
|
||||
static int
|
||||
equiv_eq (const void *p1, const void *p2)
|
||||
{
|
||||
tree value1 = ((struct equiv_hash_elt *)p1)->value;
|
||||
tree value2 = ((struct equiv_hash_elt *)p2)->value;
|
||||
|
||||
return operand_equal_p (value1, value2, 0);
|
||||
}
|
||||
|
||||
/* Remove the most recently recorded equivalency for VALUE. */
|
||||
|
||||
static void
|
||||
remove_equivalence (tree value)
|
||||
{
|
||||
struct equiv_hash_elt equiv_hash_elt, *equiv_hash_elt_p;
|
||||
void **slot;
|
||||
|
||||
equiv_hash_elt.value = value;
|
||||
equiv_hash_elt.equivalences = NULL;
|
||||
|
||||
slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT);
|
||||
|
||||
equiv_hash_elt_p = (struct equiv_hash_elt *) *slot;
|
||||
VARRAY_POP (equiv_hash_elt_p->equivalences);
|
||||
}
|
||||
|
||||
/* Record EQUIVALENCE = VALUE into our hash table. */
|
||||
|
||||
static void
|
||||
record_equiv (tree value, tree equivalence)
|
||||
{
|
||||
struct equiv_hash_elt *equiv_hash_elt;
|
||||
void **slot;
|
||||
|
||||
equiv_hash_elt = xmalloc (sizeof (struct equiv_hash_elt));
|
||||
equiv_hash_elt->value = value;
|
||||
equiv_hash_elt->equivalences = NULL;
|
||||
|
||||
slot = htab_find_slot (equiv, equiv_hash_elt, INSERT);
|
||||
|
||||
if (*slot == NULL)
|
||||
*slot = (void *) equiv_hash_elt;
|
||||
else
|
||||
free (equiv_hash_elt);
|
||||
|
||||
equiv_hash_elt = (struct equiv_hash_elt *) *slot;
|
||||
|
||||
if (!equiv_hash_elt->equivalences)
|
||||
VARRAY_TREE_INIT (equiv_hash_elt->equivalences, 10, "value equivs");
|
||||
VARRAY_PUSH_TREE (equiv_hash_elt->equivalences, equivalence);
|
||||
}
|
||||
|
||||
/* Main driver for un-cprop. */
|
||||
|
||||
static void
|
||||
tree_ssa_uncprop (void)
|
||||
{
|
||||
struct dom_walk_data walk_data;
|
||||
basic_block bb;
|
||||
|
||||
associate_equivalences_with_edges ();
|
||||
|
||||
/* Create our global data structures. */
|
||||
equiv = htab_create (1024, equiv_hash, equiv_eq, free);
|
||||
VARRAY_TREE_INIT (equiv_stack, 2, "Block equiv stack");
|
||||
|
||||
/* We're going to do a dominator walk, so ensure that we have
|
||||
dominance information. */
|
||||
calculate_dominance_info (CDI_DOMINATORS);
|
||||
|
||||
/* Setup callbacks for the generic dominator tree walker. */
|
||||
walk_data.walk_stmts_backward = false;
|
||||
walk_data.dom_direction = CDI_DOMINATORS;
|
||||
walk_data.initialize_block_local_data = NULL;
|
||||
walk_data.before_dom_children_before_stmts = uncprop_initialize_block;
|
||||
walk_data.before_dom_children_walk_stmts = NULL;
|
||||
walk_data.before_dom_children_after_stmts = uncprop_into_successor_phis;
|
||||
walk_data.after_dom_children_before_stmts = NULL;
|
||||
walk_data.after_dom_children_walk_stmts = NULL;
|
||||
walk_data.after_dom_children_after_stmts = uncprop_finalize_block;
|
||||
walk_data.global_data = NULL;
|
||||
walk_data.block_local_data_size = 0;
|
||||
walk_data.interesting_blocks = NULL;
|
||||
|
||||
/* Now initialize the dominator walker. */
|
||||
init_walk_dominator_tree (&walk_data);
|
||||
|
||||
/* Recursively walk the dominator tree undoing unprofitable
|
||||
constant/copy propagations. */
|
||||
walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR);
|
||||
|
||||
/* Finalize and clean up. */
|
||||
fini_walk_dominator_tree (&walk_data);
|
||||
|
||||
/* EQUIV_STACK should already be empty at this point, so we just need
|
||||
to empty elements out of the hash table and cleanup the AUX field
|
||||
on the edges. */
|
||||
htab_delete (equiv);
|
||||
FOR_EACH_BB (bb)
|
||||
{
|
||||
edge e;
|
||||
edge_iterator ei;
|
||||
|
||||
FOR_EACH_EDGE (e, ei, bb->succs)
|
||||
{
|
||||
if (e->aux)
|
||||
{
|
||||
free (e->aux);
|
||||
e->aux = NULL;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
|
||||
/* We have finished processing the dominator children of BB, perform
|
||||
any finalization actions in preparation for leaving this node in
|
||||
the dominator tree. */
|
||||
|
||||
static void
|
||||
uncprop_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
||||
basic_block bb ATTRIBUTE_UNUSED)
|
||||
{
|
||||
tree value = VARRAY_TOP_TREE (equiv_stack);
|
||||
|
||||
/* Pop the topmost value off the equiv stack. */
|
||||
VARRAY_POP (equiv_stack);
|
||||
|
||||
/* If that value was non-null, then pop the topmost equivalency off
|
||||
its equivalency stack. */
|
||||
if (value != NULL)
|
||||
remove_equivalence (value);
|
||||
}
|
||||
|
||||
/* Unpropagate values from PHI nodes in successor blocks of BB. */
|
||||
|
||||
static void
|
||||
uncprop_into_successor_phis (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
||||
basic_block bb)
|
||||
{
|
||||
edge e;
|
||||
edge_iterator ei;
|
||||
|
||||
/* For each successor edge, first temporarily record any equivalence
|
||||
on that edge. Then unpropagate values in any PHI nodes at the
|
||||
destination of the edge. Then remove the temporary equivalence. */
|
||||
FOR_EACH_EDGE (e, ei, bb->succs)
|
||||
{
|
||||
tree phi = phi_nodes (e->dest);
|
||||
|
||||
/* If there are no PHI nodes in this destination, then there is
|
||||
no sense in recording any equivalences. */
|
||||
if (!phi)
|
||||
continue;
|
||||
|
||||
/* Record any equivalency associated with E. */
|
||||
if (e->aux)
|
||||
{
|
||||
struct edge_equivalency *equiv = e->aux;
|
||||
record_equiv (equiv->rhs, equiv->lhs);
|
||||
}
|
||||
|
||||
/* Walk over the PHI nodes, unpropagating values. */
|
||||
for ( ; phi; phi = PHI_CHAIN (phi))
|
||||
{
|
||||
/* Sigh. We'll have more efficient access to this one day. */
|
||||
tree arg = PHI_ARG_DEF (phi, e->dest_idx);
|
||||
struct equiv_hash_elt equiv_hash_elt;
|
||||
void **slot;
|
||||
|
||||
/* If the argument is not an invariant, or refers to the same
|
||||
underlying variable as the PHI result, then there's no
|
||||
point in un-propagating the argument. */
|
||||
if (!is_gimple_min_invariant (arg)
|
||||
&& SSA_NAME_VAR (arg) != SSA_NAME_VAR (PHI_RESULT (phi)))
|
||||
continue;
|
||||
|
||||
/* Lookup this argument's value in the hash table. */
|
||||
equiv_hash_elt.value = arg;
|
||||
equiv_hash_elt.equivalences = NULL;
|
||||
slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT);
|
||||
|
||||
if (slot)
|
||||
{
|
||||
struct equiv_hash_elt *elt = *slot;
|
||||
int j;
|
||||
|
||||
/* Walk every equivalence with the same value. If we find
|
||||
one with the same underlying variable as the PHI result,
|
||||
then replace the value in the argument with its equivalent
|
||||
SSA_NAME. Use the most recent equivlance as hopefully
|
||||
that results in shortest lifetimes. */
|
||||
for (j = VARRAY_ACTIVE_SIZE (elt->equivalences) - 1; j >= 0; j--)
|
||||
{
|
||||
tree equiv = VARRAY_TREE (elt->equivalences, j);
|
||||
|
||||
if (SSA_NAME_VAR (equiv) == SSA_NAME_VAR (PHI_RESULT (phi)))
|
||||
{
|
||||
SET_PHI_ARG_DEF (phi, e->dest_idx, equiv);
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/* If we had an equivalence associated with this edge, remove it. */
|
||||
if (e->aux)
|
||||
{
|
||||
struct edge_equivalency *equiv = e->aux;
|
||||
remove_equivalence (equiv->rhs);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/* Ignoring loop backedges, if BB has precisely one incoming edge then
|
||||
return that edge. Otherwise return NULL. */
|
||||
static edge
|
||||
single_incoming_edge_ignoring_loop_edges (basic_block bb)
|
||||
{
|
||||
edge retval = NULL;
|
||||
edge e;
|
||||
edge_iterator ei;
|
||||
|
||||
FOR_EACH_EDGE (e, ei, bb->preds)
|
||||
{
|
||||
/* A loop back edge can be identified by the destination of
|
||||
the edge dominating the source of the edge. */
|
||||
if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest))
|
||||
continue;
|
||||
|
||||
/* If we have already seen a non-loop edge, then we must have
|
||||
multiple incoming non-loop edges and thus we return NULL. */
|
||||
if (retval)
|
||||
return NULL;
|
||||
|
||||
/* This is the first non-loop incoming edge we have found. Record
|
||||
it. */
|
||||
retval = e;
|
||||
}
|
||||
|
||||
return retval;
|
||||
}
|
||||
|
||||
static void
|
||||
uncprop_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED,
|
||||
basic_block bb)
|
||||
{
|
||||
basic_block parent;
|
||||
edge e;
|
||||
bool recorded = false;
|
||||
|
||||
/* If this block is dominated by a single incoming edge and that edge
|
||||
has an equivalency, then record the equivalency and push the
|
||||
VALUE onto EQUIV_STACK. Else push a NULL entry on EQUIV_STACK. */
|
||||
parent = get_immediate_dominator (CDI_DOMINATORS, bb);
|
||||
if (parent)
|
||||
{
|
||||
e = single_incoming_edge_ignoring_loop_edges (bb);
|
||||
|
||||
if (e && e->src == parent && e->aux)
|
||||
{
|
||||
struct edge_equivalency *equiv = e->aux;
|
||||
|
||||
record_equiv (equiv->rhs, equiv->lhs);
|
||||
VARRAY_PUSH_TREE (equiv_stack, equiv->rhs);
|
||||
recorded = true;
|
||||
}
|
||||
}
|
||||
|
||||
if (!recorded)
|
||||
VARRAY_PUSH_TREE (equiv_stack, NULL_TREE);
|
||||
}
|
||||
|
||||
static bool
|
||||
gate_uncprop (void)
|
||||
{
|
||||
return flag_tree_dom != 0;
|
||||
}
|
||||
|
||||
struct tree_opt_pass pass_uncprop =
|
||||
{
|
||||
"uncprop", /* name */
|
||||
gate_uncprop, /* gate */
|
||||
tree_ssa_uncprop, /* execute */
|
||||
NULL, /* sub */
|
||||
NULL, /* next */
|
||||
0, /* static_pass_number */
|
||||
TV_TREE_SSA_UNCPROP, /* tv_id */
|
||||
PROP_cfg | PROP_ssa, /* properties_required */
|
||||
0, /* properties_provided */
|
||||
0, /* properties_destroyed */
|
||||
0, /* todo_flags_start */
|
||||
TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */
|
||||
0 /* letter */
|
||||
};
|
Loading…
Reference in New Issue
Block a user