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UMERGE(1-SysV)							UMERGE(1-SysV)

NAME    [Toc]    [Back]

     umerge - Ucode Inliner

SYNOPSIS    [Toc]    [Back]

     umerge input_file -o inlined_file [ -t sym_file -i	control_file
     -space_time value -inline_to value	] [ -v -noinline -inline_all
     -no_init_to_ass -no_promotion ]

DESCRIPTION    [Toc]    [Back]

     umerge, the ucode inliner,	reads the input	binary ucode file into an
     input ucode buffer.  An output ucode buffer is then allocated.  umerge
     then makes	a pass over the	input ucode buffer to collect information and
     build data	structures, including the program call graph.  This pass also
     copies all	top-level non-procedure	ucode to the output buffer.  It	then
     analyzes the data structures to decide what to do for the output ucode.
     Finally, it copies	the code from the input	buffer to the output buffer
     according to a depth-first, post-order traversal of the program call
     graph.  In	this process, procedure	bodies are conditionally integrated at
     their points of calls.  When inlining procedures, the procedure code is
     taken from	the output buffer.  This allows	the output of integrating
     procedure A into B	to be used when	procedure B is later integrated	into
     procedure C.

     Apart from	the above basic	functions, umerge also does additional
     optimizations that	naturally belong to it.	 For FORTRAN programs, it
     promotes reference	parameters to value parameters whenever	this can
     safely be performed.  When	the actual parameter is	a constant, it fetches
     the constant value	from the INIT ucode and	passes the constants directly.
     When the actual parameter is an initialized variable that is never
     written in	the whole program, it also looks up the	initialized value and
     passes the	constant value directly.

     umerge also recognizes initialized	variables that are never written into
     and converts the initializations to run-time assignments at the beginning
     of	the procedures.	 This allows the later global optimizer	to perform
     constant propagation, constant folding and	dead store elimination to
     further improve the code.

     The following options are interpreted by umerge.

     -v	     Turns on verbose mode.  In	this mode, umerge will print the name
	     of	the procedure it is currently copying to the output buffer.
	     It	also prints the	name of	the procedure it is inlining at	each
	     call site.

	     Suppresses	the inlining functionality.  All other optimizations
	     are still performed.

	     Inline all	calls in the program.  This option should only be used
	     with discretion, since it can create tremendous optimization

									Page 1

UMERGE(1-SysV)							UMERGE(1-SysV)

	     overhead in the later optimization	phases.

	     Turns off umerge's	initialization to run-time assignment

	     Turns off reference parameter to value parameter promotion.

     -t	sym_file
	     Tells umerge the name of the symbol table file.  This is
	     necessary for umerge to know the names of all the procedures.

     -i	control_file
	     Gives direct control over umerge on the inlining of specific
	     procedures.  The control file must	be made	up of lines that start
	     with a "+"	or a "-" in the	first column, followed by a procedure
	     name.  The	procedures can be listed in arbitrary order in the
	     file.  Procedures marked with "+" are always inlined, and those
	     marked with "-" are never inlined.

     -space_time value
	     Uses the given value for this parameter.  umerge's	inlining
	     decision is based on this parameter that represents space/time
	     tradeoff.	The default value is 3.0.  This	tells umerge that a
	     size increase of 3	instructions is	worthy of each cycle reduction
	     in	execution time.	 In other words, umerge	will inline a
	     procedure whenever	the inlining causes 3 or less additional
	     instructions in code size for every 1 cycle speedup in execution
	     time.  The	value specified	in this	option does not	need to	be a
	     whole number.

     -inline_to	value
	     The default value of this parameter is 0. A positive value	of
	     this parameter asks umerge	to perform additional inlining of
	     calls to leaf routines up to the specified	level, in addition to
	     its automatic decision mechanism. A value of 1 will cause all
	     calls to leaf procedures to be inlined.  A	value of 2 will
	     additionally cause	all calls to procedures	that became leaves due
	     to	level 1	inlining to be inlined,	etc.  Under this option, a
	     procedure will become a leaf in the inlined output	code if	and
	     only if the procedure's maximum distance from a leaf in the call
	     graph is less than	or equal to the	value of this parameter.  This
	     option is not affected by the -noinline option.

SEE ALSO    [Toc]    [Back]

     ucode(1), btou(1),

DIAGNOSTICS    [Toc]    [Back]

     umerge assumes the	input ucode file is error-free.	 Otherwise, there is
     no	guarantee on its behavior.

									PPPPaaaaggggeeee 2222
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