Enhancements for the if-conversion pass

From-SVN: r55624

gcc/ChangeLog

+2002-07-21  Bernd Schmidt  <bernds@redhat.com>
+
+	Improvements for the ifcvt pass from Michael Meissner, with patches
+	by Richard Sandiford <rsandifo@redhat.com>
+	* basic-block.h (struct ce_if_block, ce_if_block_t): New types.
+	* ifcvt.c (cond_exec_changed_p): New static variable.
+	(last_active_insn): New function, renamed from last_active_insn_p
+	and changed to return the last active insn in a basic block. All
+	callers updated.
+	(block_fallthru): New function.
+	(cond_exec_process_insns): New argument CE_INFO.  Pass it to
+	IFCVT_MODIFY_INSN.  All callers updated.
+	Return false if START or END are NULL.
+	Handle case where we're processing an insn that is already
+	conditional.
+
+	(noce_process_if_block): CE_INFO argument rather than
+	multiple args containing the involved basic blocks.  All callers
+	changed.
+	(process_if_block, merge_if_block, find_if_block,
+	cond_exec_process_if_block): Likewise.
+
+	(cond_exec_process_if_block): New arg DO_MULTIPLE_P.  All callers
+	changed.
+	Use new function last_active_insn to simplify some code.
+	New code to handle multiple tests.
+	Call IFCVT_MODIFY_CANCEL in all failure cases, otherwise set
+	cond_exec_changed_p to TRUE.
+
+	(process_if_block): New code to handle multiple tests.
+	(merge_if_block): Likewise.
+	(find_if_header): New arg PASS.  Changed to return the currently
+	processed basic block or NULL instead of true/false. All callers
+	changed.
+	Call IFCVT_INIT_EXTRA_FIELDS.
+	(block_jumps_and_fallthru_p): New function.
+	(find_if_block): Discover opportunities to convert multiple tests.
+	Add additional debugging output.
+	Update the ce_info structure before returning.
+
+	(if_convert): Run multiple passes of if-conversion.
+	* doc/tm.texi (IFCVT_MODIFY_TESTS, IFCVT_MODIFY_INSN,
+	IFCVT_MODIFY_FINAL, IFCVT_MODIFY_CANCEL, IFCVT_MODIFY_MULTIPLE_TESTS,
+	IFCVT_INIT_EXTRA_FIELDS, IFCVT_EXTRA_FIELDS): Update documentation for
+	these macros.
+
 Sun Jul 21 00:54:54 CEST 2002  Jan Hubicka  <jh@suse.cz>
 
 	* gcse.c: Include cselib.h

gcc/basic-block.h

@@ -523,6 +523,33 @@ struct loops
   sbitmap shared_headers;
 };
 
+/* Structure to group all of the information to process IF-THEN and
+   IF-THEN-ELSE blocks for the conditional execution support.  This
+   needs to be in a public file in case the IFCVT macros call
+   functions passing the ce_if_block data structure.  */
+
+typedef struct ce_if_block
+{
+  basic_block test_bb;			/* First test block.  */
+  basic_block then_bb;			/* THEN block.  */
+  basic_block else_bb;			/* ELSE block or NULL.  */
+  basic_block join_bb;			/* Join THEN/ELSE blocks.  */
+  basic_block last_test_bb;		/* Last bb to hold && or || tests.  */
+  int num_multiple_test_blocks;		/* # of && and || basic blocks.  */
+  int num_and_and_blocks;		/* # of && blocks.  */
+  int num_or_or_blocks;			/* # of || blocks.  */
+  int num_multiple_test_insns;		/* # of insns in && and || blocks.  */
+  int and_and_p;			/* Complex test is &&.  */
+  int num_then_insns;			/* # of insns in THEN block.  */
+  int num_else_insns;			/* # of insns in ELSE block.  */
+  int pass;				/* Pass number.  */
+
+#ifdef IFCVT_EXTRA_FIELDS
+  IFCVT_EXTRA_FIELDS			/* Any machine dependent fields.  */
+#endif
+
+} ce_if_block_t;
+
 extern int flow_loops_find PARAMS ((struct loops *, int flags));
 extern int flow_loops_update PARAMS ((struct loops *, int flags));
 extern void flow_loops_free PARAMS ((struct loops *));

gcc/doc/tm.texi

@@ -8813,29 +8813,54 @@ conditional execution instructions instead of a branch.  A value of
 1 if it does use cc0.
 
 @findex IFCVT_MODIFY_TESTS
-@item IFCVT_MODIFY_TESTS
-A C expression to modify the tests in @code{TRUE_EXPR}, and
-@code{FALSE_EXPR} for use in converting insns in @code{TEST_BB},
-@code{THEN_BB}, @code{ELSE_BB}, and @code{JOIN_BB} basic blocks to
-conditional execution.  Set either @code{TRUE_EXPR} or @code{FALSE_EXPR}
-to a null pointer if the tests cannot be converted.
+@item IFCVT_MODIFY_TESTS(@var{ce_info}, @var{true_expr}, @var{false_expr})
+Used if the target needs to perform machine-dependent modifications on the
+conditionals used for turning basic blocks into conditionally executed code.
+@var{ce_info} points to a data structure, @code{struct ce_if_block}, which
+contains information about the currently processed blocks.  @var{true_expr}
+and @var{false_expr} are the tests that are used for converting the
+then-block and the else-block, respectively.  Set either @var{true_expr} or
+@var{false_expr} to a null pointer if the tests cannot be converted.
+
+@findex IFCVT_MODIFY_MULTIPLE_TESTS
+@item IFCVT_MODIFY_MULTIPLE_TESTS(@var{ce_info}, @var{bb}, @var{true_expr}, @var{false_expr})
+Like @code{IFCVT_MODIFY_TESTS}, but used when converting more complicated
+if-statements into conditions combined by @code{and} and @code{or} operations.
+@var{bb} contains the basic block that contains the test that is currently
+being processed and about to be turned into a condition.
 
 @findex IFCVT_MODIFY_INSN
-@item IFCVT_MODIFY_INSN
-A C expression to modify the @code{PATTERN} of an @code{INSN} that is to
-be converted to conditional execution format.
+@item IFCVT_MODIFY_INSN(@var{ce_info}, @var{pattern}, @var{insn})
+A C expression to modify the @var{PATTERN} of an @var{INSN} that is to
+be converted to conditional execution format.  @var{ce_info} points to
+a data structure, @code{struct ce_if_block}, which contains information
+about the currently processed blocks.
 
 @findex IFCVT_MODIFY_FINAL
-@item IFCVT_MODIFY_FINAL
+@item IFCVT_MODIFY_FINAL(@var{ce_info})
 A C expression to perform any final machine dependent modifications in
-converting code to conditional execution in the basic blocks
-@code{TEST_BB}, @code{THEN_BB}, @code{ELSE_BB}, and @code{JOIN_BB}.
+converting code to conditional execution.  The involved basic blocks
+can be found in the @code{struct ce_if_block} structure that is pointed
+to by @var{ce_info}.
 
 @findex IFCVT_MODIFY_CANCEL
-@item IFCVT_MODIFY_CANCEL
+@item IFCVT_MODIFY_CANCEL(@var{ce_info})
 A C expression to cancel any machine dependent modifications in
-converting code to conditional execution in the basic blocks
-@code{TEST_BB}, @code{THEN_BB}, @code{ELSE_BB}, and @code{JOIN_BB}.
+converting code to conditional execution.  The involved basic blocks
+can be found in the @code{struct ce_if_block} structure that is pointed
+to by @var{ce_info}.
+
+@findex IFCVT_INIT_EXTRA_FIELDS
+@item IFCVT_INIT_EXTRA_FIELDS(@var{ce_info})
+A C expression to initialize any extra fields in a @code{struct ce_if_block}
+structure, which are defined by the @code{IFCVT_EXTRA_FIELDS} macro.
+
+@findex IFCVT_EXTRA_FIELDS
+@item IFCVT_EXTRA_FIELDS
+If defined, it should expand to a set of field declarations that will be
+added to the @code{struct ce_if_block} structure.  These should be intialized
+by the @code{IFCVT_INIT_EXTRA_FIELDS} macro.
+
 @end table
 
 @deftypefn {Target Hook} void TARGET_INIT_BUILTINS ()