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re PR tree-optimization/26242 (VRP is not documented in passes.texi)

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PR 26242
	* doc/passes.texi: Add documentation for pass_vrp, pass_ipa_pta,
	pass_fre, pass_store_ccp, pass_copy_prop,
	pass_store_copy_prop, pass_merge_phi, pass_nrv,
	pass_return_slot, pass_object_size, pass_lim,
	pass_linear_transform, pass_empty_loop, pass_complete_unroll,
	pass_loop_prefetch and pass_stdarg.

From-SVN: r114200
This commit is contained in:
Diego Novillo 2006-05-29 14:57:39 +00:00 committed by Diego Novillo
parent 6614f9f559
commit a6719dc6ad
2 changed files with 145 additions and 15 deletions
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10
gcc/ChangeLog
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@ -1,3 +1,13 @@
2006-05-29 Diego Novillo <dnovillo@redhat.com>
PR 26242
* doc/passes.texi: Add documentation for pass_vrp, pass_ipa_pta,
pass_fre, pass_store_ccp, pass_copy_prop,
pass_store_copy_prop, pass_merge_phi, pass_nrv,
pass_return_slot, pass_object_size, pass_lim,
pass_linear_transform, pass_empty_loop, pass_complete_unroll,
pass_loop_prefetch and pass_stdarg.
2005-05-29 Bernd Schmidt <bernd.schmidt@analog.com>
* config/bfin/bfin.opt (mfdpic): New option.

150
gcc/doc/passes.texi
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@ -265,7 +265,7 @@ and is described by @code{pass_referenced_vars}.
This pass rewrites the function such that it is in SSA form. After
this pass, all @code{is_gimple_reg} variables will be referenced by
@code{SSA_NAME}, and all occurrences of other variables will be
annotated with @code{VDEFS} and @code{VUSES}; phi nodes will have
annotated with @code{VDEFS} and @code{VUSES}; PHI nodes will have
been inserted as necessary for each basic block. This pass is
located in @file{tree-ssa.c} and is described by @code{pass_build_ssa}.
@ -295,9 +295,9 @@ expression simplification, and jump threading. It is run multiple times
throughout the optimization process. It it located in @file{tree-ssa-dom.c}
and is described by @code{pass_dominator}.
@item Redundant phi elimination
@item Redundant PHI elimination
This pass removes phi nodes for which all of the arguments are the same
This pass removes PHI nodes for which all of the arguments are the same
value, excluding feedback. Such degenerate forms are typically created
by removing unreachable code. The pass is run multiple times throughout
the optimization process. It is located in @file{tree-ssa.c} and is
@ -321,7 +321,7 @@ located in @file{tree-ssa-copyrename.c} and is described by
@item PHI node optimizations
This pass recognizes forms of phi inputs that can be represented as
This pass recognizes forms of PHI inputs that can be represented as
conditional expressions and rewrites them into straight line code.
It is located in @file{tree-ssa-phiopt.c} and is described by
@code{pass_phiopt}.
@ -336,6 +336,9 @@ update the @code{VDEF}/@code{VUSE} memory tags for non-renamable
aggregates so that we get fewer false kills. The pass is located
in @file{tree-ssa-alias.c} and is described by @code{pass_may_alias}.
Interprocedural points-to information is located in
@file{tree-ssa-structalias.c} and described by @code{pass_ipa_pta}.
@item Profiling
This pass rewrites the function in order to collect runtime block
@ -387,6 +390,12 @@ divisions to multiplications by the reciprocal. The pass is located
in @file{tree-ssa-math-opts.c} and is described by
@code{pass_cse_reciprocal}.
@item Full redundancy elimination
This is a simpler form of PRE that only eliminate redundancies that
occur an all paths. It is located in @file{tree-ssa-pre.c} and
described by @code{pass_fre}.
@item Loop optimization
The main driver of the pass is placed in @file{tree-ssa-loop.c}
@ -440,11 +449,12 @@ Analysis of data references is in @file{tree-data-ref.c}.
@item Tree level if-conversion for vectorizer
This pass applies if-conversion to simple loops to help vectorizer.
We identify if convertable loops, if-convert statements and merge
We identify if convertible loops, if-convert statements and merge
basic blocks in one big block. The idea is to present loop in such
form so that vectorizer can have one to one mapping between statements
and available vector operations. This patch re-introduces COND_EXPR
at GIMPLE level. This pass is located in @file{tree-if-conv.c}.
at GIMPLE level. This pass is located in @file{tree-if-conv.c} and is
described by @code{pass_if_conversion}.
@item Conditional constant propagation
@ -453,9 +463,38 @@ that must be constant even in the presence of conditional branches.
The pass is located in @file{tree-ssa-ccp.c} and is described
by @code{pass_ccp}.
@item Folding builtin functions
A related pass that works on memory loads and stores, and not just
register values, is located in @file{tree-ssa-ccp.c} and described by
@code{pass_store_ccp}.
This pass simplifies builtin functions, as applicable, with constant
@item Conditional copy propagation
This is similar to constant propagation but the lattice of values is
the ``copy-of'' relation. It eliminates redundant copies from the
code. The pass is located in @file{tree-ssa-copy.c} and described by
@code{pass_copy_prop}.
A related pass that works on memory copies, and not just register
copies, is located in @file{tree-ssa-copy.c} and described by
@code{pass_store_copy_prop}.
@item Value range propagation
This transformation is similar to constant propagation but
instead of propagating single constant values, it propagates
known value ranges. The implementation is based on Patterson's
range propagation algorithm (Accurate Static Branch Prediction by
Value Range Propagation, J. R. C. Patterson, PLDI '95). In
contrast to Patterson's algorithm, this implementation does not
propagate branch probabilities nor it uses more than a single
range per SSA name. This means that the current implementation
cannot be used for branch prediction (though adapting it would
not be difficult). The pass is located in @file{tree-vrp.c} and is
described by @code{pass_vrp}.
@item Folding built-in functions
This pass simplifies built-in functions, as applicable, with constant
arguments or with inferrable string lengths. It is located in
@file{tree-ssa-ccp.c} and is described by @code{pass_fold_builtins}.
@ -465,12 +504,6 @@ This pass identifies critical edges and inserts empty basic blocks
such that the edge is no longer critical. The pass is located in
@file{tree-cfg.c} and is described by @code{pass_split_crit_edges}.
@item Partial redundancy elimination
This pass answers the question ``given a hypothetical temporary
variable, what expressions could we eliminate?'' It is located
in @file{tree-ssa-pre.c} and is described by @code{pass_pre}.
@item Control dependence dead code elimination
This pass is a stronger form of dead code elimination that can
@ -514,7 +547,94 @@ is described by @code{pass_mudflap_2}.
This pass rewrites the function such that it is in normal form. At
the same time, we eliminate as many single-use temporaries as possible,
so the intermediate language is no longer GIMPLE, but GENERIC@. The
pass is located in @file{tree-ssa.c} and is described by @code{pass_del_ssa}.
pass is located in @file{tree-outof-ssa.c} and is described by
@code{pass_del_ssa}.
@item Merge PHI nodes that feed into one another
This is part of the CFG cleanup passes. It attempts to join PHI nodes
from a forwarder CFG block into another block with PHI nodes. The
pass is located in @file{tree-cfgcleanup.c} and is described by
@code{pass_merge_phi}.
@item Return value optimization
If a function always returns the same local variable, and that local
variable is an aggregate type, then the variable is replaced with the
return value for the function (i.e., the function's DECL_RESULT). This
is equivalent to the C++ named return value optimization applied to
GIMPLE. The pass is located in @file{tree-nrv.c} and is described by
@code{pass_nrv}.
@item Return slot optimization
If a function returns a memory object and is called as @code{var =
foo()}, this pass tries to change the call so that the address of
@code{var} is sent to the caller to avoid an extra memory copy. This
pass is located in @code{tree-nrv.c} and is described by
@code{pass_return_slot}.
@item Optimize calls to @code{__builtin_object_size}
This is a propagation pass similar to CCP that tries to remove calls
to @code{__builtin_object_size} when the size of the object can be
computed at compile-time. This pass is located in
@file{tree-object-size.c} and is described by
@code{pass_object_sizes}.
@item Loop invariant motion
This pass removes expensive loop-invariant computations out of loops.
The pass is located in @file{tree-ssa-loop.c} and described by
@code{pass_lim}.
@item Loop nest optimizations
This is a family of loop transformations that works on loop nests. It
includes loop interchange, scaling, skewing and reversal and they are
all geared to the optimization of data locality in array traversals
and the removal of dependencies that hamper optimizations such as loop
parallelization and vectorization. The pass is located in
@file{tree-loop-linear.c} and described by
@code{pass_linear_transform}.
@item Removal of empty loops
This pass removes loops with no code in them. The pass is located in
@file{tree-ssa-loop-ivcanon.c} and described by
@code{pass_empty_loop}.
@item Unrolling of small loops
This pass completely unrolls loops with few iterations. The pass
is located in @file{tree-ssa-loop-ivcanon.c} and described by
@code{pass_complete_unroll}.
@item Array prefetching
This pass issues prefetch instructions for array references inside
loops. The pass is located in @file{tree-ssa-loop-prefetch.c} and
described by @code{pass_loop_prefetch}.
@item Reassociation
This pass rewrites arithmetic expressions to enable optimizations that
operate on them, like redundancy elimination and vectorization. The
pass is located in @file{tree-ssa-reassoc.c} and described by
@code{pass_reassoc}.
@item Optimization of @code{stdarg} functions
This pass tries to avoid the saving of register arguments into the
stack on entry to @code{stdarg} functions. If the function doesn't
use any @code{va_start} macros, no registers need to be saved. If
@code{va_start} macros are used, the @code{va_list} variables don't
escape the function, it is only necessary to save registers that will
be used in @code{va_arg} macros. For instance, if @code{va_arg} is
only used with integral types in the function, floating point
registers don't need to be saved. This pass is located in
@code{tree-stdarg.c} and described by @code{pass_stdarg}.
@end itemize
@node RTL passes