2006-01-24 Frank Ch. Eigler <fche@elastic.org>

	PR 2060 etc.
	* tapsets.cxx (visit_target_symbol): Tolerate failed resolution by
	letting target_symbol instance pass through to optimizer and
	type checker.
	* elaborate.cxx (semantic_pass_optimize): New family of functions and
	associated visitor classes.
	(visit_for_loop): Tolerate absent init/incr clauses.
	(semantic_pass): Invoke unless unoptimized (-u) option given.
	* main.cxx, session.h: Add support for flag.
	* staptree.cxx (visit_for_loop): Tolerate absent init/incr clauses.
	(traversing_visitor::visit_arrayindex): Visit the index expressions.
	(functioncall_traversing_visitor): New class.
	(varuse_tracking_visitor): New class.
	* staptree.h: Corresponding changes.
	* parse.cxx (parse_for_loop): Represent absent init/incr expressions
	with null statement pointer instead of optimized-out dummy numbers.
	* stap.1.in: Document optimization.
	* testsuite/{semko,transko}/*.stp: Added "-u" or other code to many
	tests to check bad code without optimizer elision.
	* testsuite/semok/optimize.stp: New test.

	* elaborate.cxx (unresolved, invalid, mismatch): Standardize error
	message wording.
	* stapfuncs.5.in: Tweak print/printf docs.
	* tapset/logging.stp: Remove redundant "print" auxiliary function,
	since it's a translator built-in.
	* testsuite/transok/five.stp: Extend test.
	* translate.cxx (emit_symbol_data): Put symbol table into a separate
	temporary header file, to make "-p3" output easier on the eyes.
	* buildrun.cxx (compile_pass): Eliminate test-mode support throughout.
	* main.cxx, session.h, translate.cxx: Ditto.
	* main.cxx (main): For last-pass=2 runs, print post-optimization ASTs.

1 files changed, 16 insertions, 4 deletions

diff --git a/stap.1.in b/stap.1.in
index d37060eb..3bc9368e 100644
--- a/stap.1.in
+++ b/stap.1.in
@@ -72,7 +72,7 @@ prints a list of supported options.
 .\" -t test mode
 .TP
 .B \-v
-Verbose mode.  Produces more informative output.
+Verbose mode.  Produce more informative output.
 .TP
 .B \-h
 Show help message.
@@ -86,9 +86,12 @@ in order to examine the generated C code, or to reuse the compiled
 kernel object.
 .TP
 .B \-g
-Guru mode.  Enables parsing of unsafe expert-level constructs like
+Guru mode.  Enable parsing of unsafe expert-level constructs like
 embedded C.
 .TP
+.B \-u
+Unoptimized mode.  Disable unused code elision during elaboration.
+.TP
 .BI \-b
 Use relayfs-based bulk mode for kernel-to-user data transfer.
 .TP
@@ -583,11 +586,11 @@ and all scripts (files named
 .IR *.stp )
 found in a tapset directory.  The directories listed
 with
-.BR -I
+.BR \-I
 are processed in sequence, each processed in "guru mode".  For each
 directory, a number of subdirectories are also searched.  These
 subdirectories are derived from the selected kernel version (the
-.BR -R
+.BR \-R
 option),
 in order to allow more kernel-version-specific scripts to override less
 specific ones.  For example, for a kernel version
@@ -617,6 +620,15 @@ appropriate kernel debugging information to be installed.  In the
 associated probe handlers, target-side variables (whose names begin
 with "$") are found and have their run-time locations decoded.
 .PP
+Next, all probes and functions are analyzed for optimization
+opportunities, in order to remove variables, expressions, and
+functions that have no useful value and no side-effect.  Since this
+process can hide latent code errors such as type mismatches or invalid
+$target variables, it sometimes may be useful to disable the
+optimizations with the
+.BR \-u
+option. 
+.PP
 Finally, all variable, function, parameter, array, and index types are
 inferred from context (literals and operators).  Stopping the
 translator after pass 2 causes it to list all the probes, functions,