Fix comments in ifconvert.
2010-04-07 Sebastian Pop <sebastian.pop@amd.com> * tree-if-conv.c: Fix indentation and comments. From-SVN: r158039
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Sebastian Pop
Sebastian Pop
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2 changed files with 64 additions and 65 deletions
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@ -1,3 +1,7 @@
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2010-04-07 Sebastian Pop <sebastian.pop@amd.com>
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* tree-if-conv.c: Fix indentation and comments.
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2010-04-06 Sebastian Pop <sebastian.pop@amd.com>
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PR middle-end/43519
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@ -134,12 +134,12 @@ static bool bb_with_exit_edge_p (struct loop *, basic_block);
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/* List of basic blocks in if-conversion-suitable order. */
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static basic_block *ifc_bbs;
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/* Main entry point.
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Apply if-conversion to the LOOP. Return true if successful otherwise return
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false. If false is returned then loop remains unchanged.
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FOR_VECTORIZER is a boolean flag. It indicates whether if-conversion is used
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for vectorizer or not. If it is used for vectorizer, additional checks are
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used. (Vectorization checks are not yet implemented). */
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/* Main entry point. Apply if-conversion to the LOOP. Return true if
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successful otherwise return false. If false is returned then loop
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remains unchanged. FOR_VECTORIZER is a boolean flag. It indicates
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whether if-conversion is used for vectorizer or not. If it is used
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for vectorizer, additional checks are used. (Vectorization checks
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are not yet implemented). */
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static bool
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tree_if_conversion (struct loop *loop, bool for_vectorizer)
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@ -150,8 +150,8 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
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ifc_bbs = NULL;
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/* if-conversion is not appropriate for all loops. First, check if loop is
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if-convertible or not. */
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/* If-conversion is not appropriate for all loops. First, check if
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loop is if-convertible or not. */
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if (!if_convertible_loop_p (loop, for_vectorizer))
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{
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if (dump_file && (dump_flags & TDF_DETAILS))
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@ -192,7 +192,7 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
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{
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basic_block bb_n = single_succ (bb);
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/* Successor bb inherits predicate of its predecessor. If there
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/* Successor bb inherits predicate of its predecessor. If there
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is no predicate in predecessor bb, then consider successor bb
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as always executed. */
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if (cond == NULL_TREE)
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@ -203,7 +203,7 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
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}
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/* Now, all statements are if-converted and basic blocks are
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annotated appropriately. Combine all basic block into one huge
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annotated appropriately. Combine all basic block into one huge
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basic block. */
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combine_blocks (loop);
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@ -215,12 +215,12 @@ tree_if_conversion (struct loop *loop, bool for_vectorizer)
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return true;
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}
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/* if-convert stmt T which is part of LOOP.
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/* If-convert stmt T which is part of LOOP.
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If T is a GIMPLE_ASSIGN then it is converted into conditional modify
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expression using COND. For conditional expressions, add condition in the
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destination basic block's predicate list and remove conditional
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expression itself. BSI is the iterator used to traverse statements of
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loop. It is used here when it is required to delete current statement. */
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expression itself. BSI is the iterator used to traverse statements of
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loop. It is used here when it is required to delete current statement. */
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static tree
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tree_if_convert_stmt (struct loop * loop, gimple t, tree cond,
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@ -249,11 +249,11 @@ tree_if_convert_stmt (struct loop * loop, gimple t, tree cond,
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break;
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case GIMPLE_ASSIGN:
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/* This GIMPLE_ASSIGN is killing previous value of LHS. Appropriate
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value will be selected by PHI node based on condition. It is possible
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/* This GIMPLE_ASSIGN is killing previous value of LHS. Appropriate
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value will be selected by PHI node based on condition. It is possible
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that before this transformation, PHI nodes was selecting default
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value and now it will use this new value. This is OK because it does
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not change validity the program. */
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value and now it will use this new value. This is OK because it does
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not change the validity of the program. */
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break;
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case GIMPLE_COND:
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@ -269,10 +269,10 @@ tree_if_convert_stmt (struct loop * loop, gimple t, tree cond,
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return cond;
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}
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/* STMT is a GIMPLE_COND. Update two destination's predicate list.
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Remove COND_EXPR, if it is not the loop exit condition. Otherwise
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/* STMT is a GIMPLE_COND. Update two destination's predicate list.
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Remove COND_EXPR, if it is not the loop exit condition. Otherwise
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update loop exit condition appropriately. GSI is the iterator
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used to traverse statement list. STMT is part of loop LOOP. */
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used to traverse statement list. STMT is part of loop LOOP. */
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static void
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tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
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@ -292,15 +292,15 @@ tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
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/* Add new condition into destination's predicate list. */
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/* If C is true then TRUE_EDGE is taken. */
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/* If C is true, then TRUE_EDGE is taken. */
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add_to_dst_predicate_list (loop, true_edge, cond, c, gsi);
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/* If 'c' is false then FALSE_EDGE is taken. */
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/* If C is false, then FALSE_EDGE is taken. */
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c2 = invert_truthvalue_loc (loc, unshare_expr (c));
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add_to_dst_predicate_list (loop, false_edge, cond, c2, gsi);
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/* Now this conditional statement is redundant. Remove it.
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But, do not remove exit condition! Update exit condition
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/* Now this conditional statement is redundant. Remove it.
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But, do not remove exit condition! Update exit condition
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using new condition. */
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if (!bb_with_exit_edge_p (loop, gimple_bb (stmt)))
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{
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@ -310,12 +310,12 @@ tree_if_convert_cond_stmt (struct loop *loop, gimple stmt, tree cond,
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return;
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}
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/* Return true, iff PHI is if-convertible. PHI is part of loop LOOP
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/* Return true, iff PHI is if-convertible. PHI is part of loop LOOP
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and it belongs to basic block BB.
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PHI is not if-convertible
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- if it has more than 2 arguments.
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- Virtual PHI is immediately used in another PHI node.
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- Virtual PHI on BB other than header. */
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- if it has more than 2 arguments,
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- virtual PHI is immediately used in another PHI node,
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- virtual PHI on BB other than header. */
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static bool
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if_convertible_phi_p (struct loop *loop, basic_block bb, gimple phi)
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@ -360,10 +360,10 @@ if_convertible_phi_p (struct loop *loop, basic_block bb, gimple phi)
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/* Return true, if STMT is if-convertible.
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GIMPLE_ASSIGN statement is not if-convertible if,
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- It is not movable.
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- It could trap.
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- it is not movable,
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- it could trap,
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- LHS is not var decl.
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GIMPLE_ASSIGN is part of block BB, which is inside loop LOOP. */
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GIMPLE_ASSIGN is part of block BB, which is inside loop LOOP. */
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static bool
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if_convertible_gimple_assign_stmt_p (struct loop *loop, basic_block bb,
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@ -420,8 +420,8 @@ if_convertible_gimple_assign_stmt_p (struct loop *loop, basic_block bb,
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/* Return true, iff STMT is if-convertible.
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Statement is if-convertible if,
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- It is if-convertible GIMPLE_ASSGIN
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- It is GIMPLE_LABEL or GIMPLE_COND.
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- it is if-convertible GIMPLE_ASSGIN,
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- it is GIMPLE_LABEL or GIMPLE_COND.
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STMT is inside block BB, which is inside loop LOOP. */
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static bool
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@ -459,10 +459,10 @@ if_convertible_stmt_p (struct loop *loop, basic_block bb, gimple stmt)
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/* Return true, iff BB is if-convertible.
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Note: This routine does _not_ check basic block statements and phis.
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Basic block is not if-convertible if,
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- Basic block is non-empty and it is after exit block (in BFS order).
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- Basic block is after exit block but before latch.
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- Basic block edge(s) is not normal.
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Basic block is not if-convertible if:
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- basic block is non-empty and it is after exit block (in BFS order),
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- basic block is after exit block but before latch,
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- basic block edge(s) is not normal.
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EXIT_BB_SEEN is true if basic block with exit edge is already seen.
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BB is inside loop LOOP. */
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@ -513,15 +513,16 @@ if_convertible_bb_p (struct loop *loop, basic_block bb, basic_block exit_bb)
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}
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/* Return true, iff LOOP is if-convertible.
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LOOP is if-convertible if,
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- It is innermost.
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- It has two or more basic blocks.
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- It has only one exit.
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- Loop header is not the exit edge.
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- If its basic blocks and phi nodes are if convertible. See above for
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LOOP is if-convertible if:
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- it is innermost,
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- it has two or more basic blocks,
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- it has only one exit,
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- loop header is not the exit edge,
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- if its basic blocks and phi nodes are if convertible. See above for
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more info.
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FOR_VECTORIZER enables vectorizer specific checks. For example, support
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for vector conditions, data dependency checks etc.. (Not implemented yet). */
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FOR_VECTORIZER enables vectorizer specific checks, for example, support
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for vector conditions, data dependency checks, etc.
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(Not implemented yet). */
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static bool
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if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
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@ -587,21 +588,16 @@ if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
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if (!if_convertible_bb_p (loop, bb, exit_bb))
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return false;
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/* Check statements. */
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for (itr = gsi_start_bb (bb); !gsi_end_p (itr); gsi_next (&itr))
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if (!if_convertible_stmt_p (loop, bb, gsi_stmt (itr)))
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return false;
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/* ??? Check data dependency for vectorizer. */
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/* What about phi nodes ? */
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itr = gsi_start_phis (bb);
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/* Clear aux field of incoming edges to a bb with a phi node. */
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if (!gsi_end_p (itr))
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FOR_EACH_EDGE (e, ei, bb->preds)
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e->aux = NULL;
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/* Check statements. */
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for (; !gsi_end_p (itr); gsi_next (&itr))
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if (!if_convertible_phi_p (loop, bb, gsi_stmt (itr)))
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return false;
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@ -610,8 +606,6 @@ if_convertible_loop_p (struct loop *loop, bool for_vectorizer ATTRIBUTE_UNUSED)
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exit_bb = bb;
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}
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/* OK. Did not find any potential issues so go ahead in if-convert
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this loop. Now there is no looking back. */
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if (dump_file)
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fprintf (dump_file,"Applying if-conversion\n");
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@ -679,7 +673,7 @@ add_to_dst_predicate_list (struct loop * loop, edge e,
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}
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/* During if-conversion aux field from basic block structure is used to hold
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predicate list. Clean each basic block's predicate list for the given LOOP.
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predicate list. Clean each basic block's predicate list for the given LOOP.
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Also clean aux field of successor edges, used to hold true and false
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condition from conditional expression. */
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@ -702,7 +696,7 @@ clean_predicate_lists (struct loop *loop)
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}
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/* Basic block BB has two predecessors. Using predecessor's aux field, set
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appropriate condition COND for the PHI node replacement. Return true block
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appropriate condition COND for the PHI node replacement. Return true block
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whose phi arguments are selected when cond is true. */
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static basic_block
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@ -1013,7 +1007,7 @@ combine_blocks (struct loop *loop)
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}
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/* Now if possible, merge loop header and block with exit edge.
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This reduces number of basic blocks to 2. Auto vectorizer addresses
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This reduces number of basic blocks to 2. Auto vectorizer addresses
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loops with two nodes only. FIXME: Use cleanup_tree_cfg(). */
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if (exit_bb
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&& exit_bb != loop->header
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@ -1021,7 +1015,7 @@ combine_blocks (struct loop *loop)
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merge_blocks (loop->header, exit_bb);
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}
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/* Make a new temp variable of type TYPE. Add GIMPLE_ASSIGN to assign EXP
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/* Make a new temp variable of type TYPE. Add GIMPLE_ASSIGN to assign EXP
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to the new variable. */
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static gimple
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@ -1064,11 +1058,11 @@ pred_blocks_visited_p (basic_block bb, bitmap *visited)
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return true;
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}
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/* Get body of a LOOP in suitable order for if-conversion.
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It is caller's responsibility to deallocate basic block
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list. If-conversion suitable order is, BFS order with one
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additional constraint. Select block in BFS block, if all
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pred are already selected. */
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/* Get body of a LOOP in suitable order for if-conversion. It is
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caller's responsibility to deallocate basic block list.
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If-conversion suitable order is, breadth first sort (BFS) order
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with an additional constraint: select a block only if all its
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predecessors are already selected. */
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static basic_block *
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get_loop_body_in_if_conv_order (const struct loop *loop)
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@ -1099,6 +1093,7 @@ get_loop_body_in_if_conv_order (const struct loop *loop)
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free (blocks);
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return NULL;
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}
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if (!bitmap_bit_p (visited, bb->index))
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{
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if (pred_blocks_visited_p (bb, &visited)
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@ -1109,13 +1104,13 @@ get_loop_body_in_if_conv_order (const struct loop *loop)
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blocks[visited_count++] = bb;
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}
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}
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index++;
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if (index == loop->num_nodes
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&& visited_count != loop->num_nodes)
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{
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/* Not done yet. */
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index = 0;
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}
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/* Not done yet. */
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index = 0;
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}
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free (blocks_in_bfs_order);
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BITMAP_FREE (visited);
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