[Docs] Cleanup pass documentation

[aidengrossman]

Summary

Currently the pass documentation specifies every pass with a single dash
(-) in front of it as this was the old format for specifying passes with
opt. However, after the transition to the new PM, this syntax is
deprecated. This patch removes all the single dashes from the pass page
to reflect this. Additionally, some previously removed/renamed passes
are removed/updated in the pass list.

[aidengrossman]

To look for dead passes I went through all the pass names and looked in the PassRegistry, grepped for the pass name at the time of conversion to restructured text, and at the current tip of tree. If it was in the pass registry, I kept it. If it was only in passes.rst at the time of conversion, I dropped it, and if it was more present I grepped the current tip of tree. If it was only present in passes.rst, I again dropped it, but otherwise kept it for the most part. Some of the functions that I've kept probably need to at least be updated as they either don't support the new pass manager/aren't registered in the pass registry currently, etc.

Some passes have been changed around to new ones (like loop-unswitch to simple-loop-unswitch) and eventually documentation needs to be written up on them, but I'll leave that to a future patch for now.

[aeubanks]

thanks for doing this!

I think we should be able to copy the loop unswitch docs for simple-loop-unswitch, they do the same thing at a high level, it's just details that differ

[aidengrossman]

Rename loop-unswitch to simple-loop-unswitch rather than removing documentation.

[aeubanks]

lg with nit

llvm/docs/Passes.rst

757–758

should put this alphabetically

llvm/docs/LoopTerminology.rst

 The major benefit of LCSSA is that it makes many other loop optimizations
 simpler.
 
 First of all, a simple observation is that if one needs to see all
 the outside users, they can just iterate over all the (loop closing)
 PHI nodes in the exit blocks (the alternative would be to
 scan the def-use chain [#def-use-chain]_ of all instructions in the loop).
 
-Then, consider for example
-:ref:`-loop-unswitch <passes-loop-unswitch>` ing the loop above.
+Then, consider for example unswitching the loop above.
 Because it is in LCSSA form, we know that any value defined inside of
 the loop will be used either only inside the loop or in a loop closing
 PHI node. In this case, the only loop closing PHI node is X4.
 This means that we can just copy the loop and change the X4
 accordingly, like so:
 
 .. code-block:: C
 

llvm/docs/Passes.rst

 provides a quick summary of each pass and links to the more complete pass
 description later in the document.
 
 Analysis Passes
 ===============
 
 This section describes the LLVM Analysis Passes.
 
-``-aa-eval``: Exhaustive Alias Analysis Precision Evaluator
------------------------------------------------------------
+``aa-eval``: Exhaustive Alias Analysis Precision Evaluator
+----------------------------------------------------------
 
 This is a simple N^2 alias analysis accuracy evaluator.  Basically, for each
 function in the program, it simply queries to see how the alias analysis
 implementation answers alias queries between each pair of pointers in the
 function.
 
 This is inspired and adapted from code by: Naveen Neelakantam, Francesco
 Spadini, and Wojciech Stryjewski.
 
-``-basic-aa``: Basic Alias Analysis (stateless AA impl)
--------------------------------------------------------
+``basic-aa``: Basic Alias Analysis (stateless AA impl)
+------------------------------------------------------
 
 A basic alias analysis pass that implements identities (two different globals
 cannot alias, etc), but does no stateful analysis.
 
-``-basiccg``: Basic CallGraph Construction
-------------------------------------------
+``basiccg``: Basic CallGraph Construction
+-----------------------------------------
 
 Yet to be written.
 
 ``-count-aa``: Count Alias Analysis Query Responses
 ---------------------------------------------------
 
 A pass which can be used to count how many alias queries are being made and how
 the alias analysis implementation being used responds.
 
 .. _passes-da:
 
-``-da``: Dependence Analysis
-----------------------------
+``da``: Dependence Analysis
+---------------------------
 
 Dependence analysis framework, which is used to detect dependences in memory
 accesses.
 
-``-debug-aa``: AA use debugger
-------------------------------
-
-This simple pass checks alias analysis users to ensure that if they create a
-new value, they do not query AA without informing it of the value.  It acts as
-a shim over any other AA pass you want.
-
-Yes keeping track of every value in the program is expensive, but this is a
-debugging pass.
-
-``-domfrontier``: Dominance Frontier Construction
--------------------------------------------------
+``domfrontier``: Dominance Frontier Construction
+------------------------------------------------
 
 This pass is a simple dominator construction algorithm for finding forward
 dominator frontiers.
 
-``-domtree``: Dominator Tree Construction
------------------------------------------
+``domtree``: Dominator Tree Construction
+----------------------------------------
 
 This pass is a simple dominator construction algorithm for finding forward
 dominators.
 
 
-``-dot-callgraph``: Print Call Graph to "dot" file
---------------------------------------------------
+``dot-callgraph``: Print Call Graph to "dot" file
+-------------------------------------------------
 
 This pass, only available in ``opt``, prints the call graph into a ``.dot``
 graph.  This graph can then be processed with the "dot" tool to convert it to
 postscript or some other suitable format.
 
-``-dot-cfg``: Print CFG of function to "dot" file
--------------------------------------------------
+``dot-cfg``: Print CFG of function to "dot" file
+------------------------------------------------
 
 This pass, only available in ``opt``, prints the control flow graph into a
 ``.dot`` graph.  This graph can then be processed with the :program:`dot` tool
 to convert it to postscript or some other suitable format.
 Additionally the ``-cfg-func-name=<substring>`` option can be used to filter the
 functions that are printed. All functions that contain the specified substring
 will be printed.
 
-``-dot-cfg-only``: Print CFG of function to "dot" file (with no function bodies)
---------------------------------------------------------------------------------
+``dot-cfg-only``: Print CFG of function to "dot" file (with no function bodies)
+-------------------------------------------------------------------------------
 
 This pass, only available in ``opt``, prints the control flow graph into a
 ``.dot`` graph, omitting the function bodies.  This graph can then be processed
 with the :program:`dot` tool to convert it to postscript or some other suitable
 format.
 Additionally the ``-cfg-func-name=<substring>`` option can be used to filter the
 functions that are printed. All functions that contain the specified substring
 will be printed.
 
-``-dot-dom``: Print dominance tree of function to "dot" file
-------------------------------------------------------------
+``dot-dom``: Print dominance tree of function to "dot" file
+-----------------------------------------------------------
 
 This pass, only available in ``opt``, prints the dominator tree into a ``.dot``
 graph.  This graph can then be processed with the :program:`dot` tool to
 convert it to postscript or some other suitable format.
 
-``-dot-dom-only``: Print dominance tree of function to "dot" file (with no function bodies)
--------------------------------------------------------------------------------------------
+``dot-dom-only``: Print dominance tree of function to "dot" file (with no function bodies)
+------------------------------------------------------------------------------------------
 
 This pass, only available in ``opt``, prints the dominator tree into a ``.dot``
 graph, omitting the function bodies.  This graph can then be processed with the
 :program:`dot` tool to convert it to postscript or some other suitable format.
 
-``-dot-post-dom``: Print postdominance tree of function to "dot" file
----------------------------------------------------------------------
+``dot-post-dom``: Print postdominance tree of function to "dot" file
+--------------------------------------------------------------------
 
 This pass, only available in ``opt``, prints the post dominator tree into a
 ``.dot`` graph.  This graph can then be processed with the :program:`dot` tool
 to convert it to postscript or some other suitable format.
 
-``-dot-post-dom-only``: Print postdominance tree of function to "dot" file (with no function bodies)
-----------------------------------------------------------------------------------------------------
+``dot-post-dom-only``: Print postdominance tree of function to "dot" file (with no function bodies)
+---------------------------------------------------------------------------------------------------
 
 This pass, only available in ``opt``, prints the post dominator tree into a
 ``.dot`` graph, omitting the function bodies.  This graph can then be processed
 with the :program:`dot` tool to convert it to postscript or some other suitable
 format.
 
-``-globalsmodref-aa``: Simple mod/ref analysis for globals
-----------------------------------------------------------
+``globals-aa``: Simple mod/ref analysis for globals
+---------------------------------------------------
 
 This simple pass provides alias and mod/ref information for global values that
 do not have their address taken, and keeps track of whether functions read or
 write memory (are "pure").  For this simple (but very common) case, we can
 provide pretty accurate and useful information.
 
-``-instcount``: Counts the various types of ``Instruction``\ s
---------------------------------------------------------------
+``instcount``: Counts the various types of ``Instruction``\ s
+-------------------------------------------------------------
 
 This pass collects the count of all instructions and reports them.
 
-``-intervals``: Interval Partition Construction
------------------------------------------------
-
-This analysis calculates and represents the interval partition of a function,
-or a preexisting interval partition.
-
-In this way, the interval partition may be used to reduce a flow graph down to
-its degenerate single node interval partition (unless it is irreducible).
-
-``-iv-users``: Induction Variable Users
----------------------------------------
+``iv-users``: Induction Variable Users
+--------------------------------------
 
 Bookkeeping for "interesting" users of expressions computed from induction
 variables.
 
-``-lazy-value-info``: Lazy Value Information Analysis
------------------------------------------------------
+``lazy-value-info``: Lazy Value Information Analysis
+----------------------------------------------------
 
 Interface for lazy computation of value constraint information.
 
-``-libcall-aa``: LibCall Alias Analysis
----------------------------------------
-
-LibCall Alias Analysis.
-
-``-lint``: Statically lint-checks LLVM IR
------------------------------------------
+``lint``: Statically lint-checks LLVM IR
+----------------------------------------
 
 This pass statically checks for common and easily-identified constructs which
 produce undefined or likely unintended behavior in LLVM IR.
 
 It is not a guarantee of correctness, in two ways.  First, it isn't
 comprehensive.  There are checks which could be done statically which are not
 yet implemented.  Some of these are indicated by TODO comments, but those
 aren't comprehensive either.  Second, many conditions cannot be checked

 be that the optimization pass is merely exposing an existing condition in the
 code.
 
 This code may be run before :ref:`instcombine <passes-instcombine>`.  In many
 cases, instcombine checks for the same kinds of things and turns instructions
 with undefined behavior into unreachable (or equivalent).  Because of this,
 this pass makes some effort to look through bitcasts and so on.
 
-``-loops``: Natural Loop Information
-------------------------------------
+``loops``: Natural Loop Information
+-----------------------------------
 
 This analysis is used to identify natural loops and determine the loop depth of
 various nodes of the CFG.  Note that the loops identified may actually be
 several natural loops that share the same header node... not just a single
 natural loop.
 
-``-memdep``: Memory Dependence Analysis
----------------------------------------
+``memdep``: Memory Dependence Analysis
+--------------------------------------
 
 An analysis that determines, for a given memory operation, what preceding
 memory operations it depends on.  It builds on alias analysis information, and
 tries to provide a lazy, caching interface to a common kind of alias
 information query.
 
-``-module-debuginfo``: Decodes module-level debug info
-------------------------------------------------------
+``module-debuginfo``: Decodes module-level debug info
+-----------------------------------------------------
 
 This pass decodes the debug info metadata in a module and prints in a
 (sufficiently-prepared-) human-readable form.
 
 For example, run this pass from ``opt`` along with the ``-analyze`` option, and
 it'll print to standard output.
 
-``-postdomfrontier``: Post-Dominance Frontier Construction
-----------------------------------------------------------
-
-This pass is a simple post-dominator construction algorithm for finding
-post-dominator frontiers.
-
-``-postdomtree``: Post-Dominator Tree Construction
---------------------------------------------------
+``postdomtree``: Post-Dominator Tree Construction
+-------------------------------------------------
 
 This pass is a simple post-dominator construction algorithm for finding
 post-dominators.
 
-``-print-alias-sets``: Alias Set Printer
-----------------------------------------
+``print-alias-sets``: Alias Set Printer
+---------------------------------------
 
 Yet to be written.
 
-``-print-callgraph``: Print a call graph
-----------------------------------------
+``print-callgraph``: Print a call graph
+---------------------------------------
 
 This pass, only available in ``opt``, prints the call graph to standard error
 in a human-readable form.
 
-``-print-callgraph-sccs``: Print SCCs of the Call Graph
--------------------------------------------------------
+``print-callgraph-sccs``: Print SCCs of the Call Graph
+------------------------------------------------------
 
 This pass, only available in ``opt``, prints the SCCs of the call graph to
 standard error in a human-readable form.
 
-``-print-cfg-sccs``: Print SCCs of each function CFG
-----------------------------------------------------
+``print-cfg-sccs``: Print SCCs of each function CFG
+---------------------------------------------------
 
 This pass, only available in ``opt``, printsthe SCCs of each function CFG to
 standard error in a human-readable fom.
 
-``-print-function``: Print function to stderr
----------------------------------------------
+``print-function``: Print function to stderr
+--------------------------------------------
 
 The ``PrintFunctionPass`` class is designed to be pipelined with other
 ``FunctionPasses``, and prints out the functions of the module as they are
 processed.
 
-``-print-module``: Print module to stderr
------------------------------------------
+``print-module``: Print module to stderr
+----------------------------------------
 
 This pass simply prints out the entire module when it is executed.
 
-.. _passes-print-used-types:
-
-``-print-used-types``: Find Used Types
---------------------------------------
-
-This pass is used to seek out all of the types in use by the program.  Note
-that this analysis explicitly does not include types only used by the symbol
-table.
-
-``-regions``: Detect single entry single exit regions
------------------------------------------------------
+``regions``: Detect single entry single exit regions
+----------------------------------------------------
 
 The ``RegionInfo`` pass detects single entry single exit regions in a function,
 where a region is defined as any subgraph that is connected to the remaining
 graph at only two spots.  Furthermore, a hierarchical region tree is built.
 
 .. _passes-scalar-evolution:
 
-``-scalar-evolution``: Scalar Evolution Analysis
-------------------------------------------------
+``scalar-evolution``: Scalar Evolution Analysis
+-----------------------------------------------
 
 The ``ScalarEvolution`` analysis can be used to analyze and categorize scalar
 expressions in loops.  It specializes in recognizing general induction
 variables, representing them with the abstract and opaque ``SCEV`` class.
 Given this analysis, trip counts of loops and other important properties can be
 obtained.
 
 This analysis is primarily useful for induction variable substitution and
 strength reduction.
 
-``-scev-aa``: ScalarEvolution-based Alias Analysis
---------------------------------------------------
+``scev-aa``: ScalarEvolution-based Alias Analysis
+-------------------------------------------------
 
 Simple alias analysis implemented in terms of ``ScalarEvolution`` queries.
 
 This differs from traditional loop dependence analysis in that it tests for
 dependencies within a single iteration of a loop, rather than dependencies
 between different iterations.
 
 ``ScalarEvolution`` has a more complete understanding of pointer arithmetic
 than ``BasicAliasAnalysis``' collection of ad-hoc analyses.
 
-``-stack-safety``: Stack Safety Analysis
-------------------------------------------------
+``stack-safety``: Stack Safety Analysis
+---------------------------------------
 
 The ``StackSafety`` analysis can be used to determine if stack allocated
 variables can be considered safe from memory access bugs.
 
 This analysis' primary purpose is to be used by sanitizers to avoid unnecessary
 instrumentation of safe variables.
 
-``-targetdata``: Target Data Layout
------------------------------------
-
-Provides other passes access to information on how the size and alignment
-required by the target ABI for various data types.
-
 Transform Passes
 ================
 
 This section describes the LLVM Transform Passes.
 
-``-adce``: Aggressive Dead Code Elimination
--------------------------------------------
+``adce``: Aggressive Dead Code Elimination
+------------------------------------------
 
 ADCE aggressively tries to eliminate code.  This pass is similar to :ref:`DCE
 <passes-dce>` but it assumes that values are dead until proven otherwise.  This
 is similar to :ref:`SCCP <passes-sccp>`, except applied to the liveness of
 values.
 
-``-always-inline``: Inliner for ``always_inline`` functions
------------------------------------------------------------
+``always-inline``: Inliner for ``always_inline`` functions
+----------------------------------------------------------
 
 A custom inliner that handles only functions that are marked as "always
 inline".
 
-``-argpromotion``: Promote 'by reference' arguments to scalars
---------------------------------------------------------------
+``argpromotion``: Promote 'by reference' arguments to scalars
+-------------------------------------------------------------
 
 This pass promotes "by reference" arguments to be "by value" arguments.  In
 practice, this means looking for internal functions that have pointer
 arguments.  If it can prove, through the use of alias analysis, that an
 argument is *only* loaded, then it can pass the value into the function instead
 of the address of the value.  This can cause recursive simplification of code
 and lead to the elimination of allocas (especially in C++ template code like
 the STL).
 
 This pass also handles aggregate arguments that are passed into a function,
 scalarizing them if the elements of the aggregate are only loaded.  Note that
 it refuses to scalarize aggregates which would require passing in more than
 three operands to the function, because passing thousands of operands for a
 large array or structure is unprofitable!
 
 Note that this transformation could also be done for arguments that are only
 stored to (returning the value instead), but does not currently.  This case
 would be best handled when and if LLVM starts supporting multiple return values
 from functions.
 
-``-bb-vectorize``: Basic-Block Vectorization
---------------------------------------------
-
-This pass combines instructions inside basic blocks to form vector
-instructions.  It iterates over each basic block, attempting to pair compatible
-instructions, repeating this process until no additional pairs are selected for
-vectorization.  When the outputs of some pair of compatible instructions are
-used as inputs by some other pair of compatible instructions, those pairs are
-part of a potential vectorization chain.  Instruction pairs are only fused into
-vector instructions when they are part of a chain longer than some threshold
-length.  Moreover, the pass attempts to find the best possible chain for each
-pair of compatible instructions.  These heuristics are intended to prevent
-vectorization in cases where it would not yield a performance increase of the
-resulting code.
-
-``-block-placement``: Profile Guided Basic Block Placement
-----------------------------------------------------------
+``block-placement``: Profile Guided Basic Block Placement
+---------------------------------------------------------
 
 This pass is a very simple profile guided basic block placement algorithm.  The
 idea is to put frequently executed blocks together at the start of the function
 and hopefully increase the number of fall-through conditional branches.  If
 there is no profile information for a particular function, this pass basically
 orders blocks in depth-first order.
 
-``-break-crit-edges``: Break critical edges in CFG
---------------------------------------------------
+``break-crit-edges``: Break critical edges in CFG
+-------------------------------------------------
 
 Break all of the critical edges in the CFG by inserting a dummy basic block.
 It may be "required" by passes that cannot deal with critical edges.  This
 transformation obviously invalidates the CFG, but can update forward dominator
 (set, immediate dominators, tree, and frontier) information.
 
-``-codegenprepare``: Optimize for code generation
--------------------------------------------------
+``codegenprepare``: Optimize for code generation
+------------------------------------------------
 
 This pass munges the code in the input function to better prepare it for
 SelectionDAG-based code generation.  This works around limitations in its
 basic-block-at-a-time approach.  It should eventually be removed.
 
-``-constmerge``: Merge Duplicate Global Constants
--------------------------------------------------
+``constmerge``: Merge Duplicate Global Constants
+------------------------------------------------
 
 Merges duplicate global constants together into a single constant that is
 shared.  This is useful because some passes (i.e., TraceValues) insert a lot of
 string constants into the program, regardless of whether or not an existing
 string is available.
 
 .. _passes-dce:
 
-``-dce``: Dead Code Elimination
--------------------------------
+``dce``: Dead Code Elimination
+------------------------------
 
-Dead code elimination is similar to :ref:`dead instruction elimination
-<passes-die>`, but it rechecks instructions that were used by removed
-instructions to see if they are newly dead.
+Dead code elimination is similar to dead instruction elimination, but it
+rechecks instructions that were used by removed instructions to see if they
+are newly dead.
 
-``-deadargelim``: Dead Argument Elimination
--------------------------------------------
+``deadargelim``: Dead Argument Elimination
+------------------------------------------
 
 This pass deletes dead arguments from internal functions.  Dead argument
 elimination removes arguments which are directly dead, as well as arguments
 only passed into function calls as dead arguments of other functions.  This
 pass also deletes dead arguments in a similar way.
 
 This pass is often useful as a cleanup pass to run after aggressive
 interprocedural passes, which add possibly-dead arguments.
 
-``-deadtypeelim``: Dead Type Elimination
-----------------------------------------
-
-This pass is used to cleanup the output of GCC.  It eliminate names for types
-that are unused in the entire translation unit, using the :ref:`find used types
-<passes-print-used-types>` pass.
-
-.. _passes-die:
-
-``-die``: Dead Instruction Elimination
---------------------------------------
-
-Dead instruction elimination performs a single pass over the function, removing
-instructions that are obviously dead.
-
-``-dse``: Dead Store Elimination
---------------------------------
+``dse``: Dead Store Elimination
+-------------------------------
 
 A trivial dead store elimination that only considers basic-block local
 redundant stores.
 
 .. _passes-function-attrs:
 
-``-function-attrs``: Deduce function attributes
------------------------------------------------
+``function-attrs``: Deduce function attributes
+----------------------------------------------
 
 A simple interprocedural pass which walks the call-graph, looking for functions
 which do not access or only read non-local memory, and marking them
 ``readnone``/``readonly``.  In addition, it marks function arguments (of
 pointer type) "``nocapture``" if a call to the function does not create any
 copies of the pointer value that outlive the call.  This more or less means
 that the pointer is only dereferenced, and not returned from the function or
 stored in a global.  This pass is implemented as a bottom-up traversal of the
 call-graph.
 
-``-globaldce``: Dead Global Elimination
----------------------------------------
+``globaldce``: Dead Global Elimination
+--------------------------------------
 
 This transform is designed to eliminate unreachable internal globals from the
 program.  It uses an aggressive algorithm, searching out globals that are known
 to be alive.  After it finds all of the globals which are needed, it deletes
 whatever is left over.  This allows it to delete recursive chunks of the
 program which are unreachable.
 
-``-globalopt``: Global Variable Optimizer
------------------------------------------
+``globalopt``: Global Variable Optimizer
+----------------------------------------
 
 This pass transforms simple global variables that never have their address
 taken.  If obviously true, it marks read/write globals as constant, deletes
 variables only stored to, etc.
 
-``-gvn``: Global Value Numbering
---------------------------------
+``gvn``: Global Value Numbering
+-------------------------------
 
 This pass performs global value numbering to eliminate fully and partially
 redundant instructions.  It also performs redundant load elimination.
 
 .. _passes-indvars:
 
-``-indvars``: Canonicalize Induction Variables
-----------------------------------------------
+``indvars``: Canonicalize Induction Variables
+---------------------------------------------
 
 This transformation analyzes and transforms the induction variables (and
 computations derived from them) into simpler forms suitable for subsequent
 analysis and transformation.
 
 This transformation makes the following changes to each loop with an
 identifiable induction variable:
 
* Any use outside of the loop of an expression derived from the indvar is
   of the loop is to compute the exit value of some derived expression, this
   transformation will make the loop dead.
 
 This transformation should be followed by strength reduction after all of the
 desired loop transformations have been performed.  Additionally, on targets
 where it is profitable, the loop could be transformed to count down to zero
 (the "do loop" optimization).
 
-``-inline``: Function Integration/Inlining
-------------------------------------------
+``inline``: Function Integration/Inlining
+-----------------------------------------
 
 Bottom-up inlining of functions into callees.
 
 .. _passes-instcombine:
 
-``-instcombine``: Combine redundant instructions
-------------------------------------------------
+``instcombine``: Combine redundant instructions
+-----------------------------------------------
 
 Combine instructions to form fewer, simple instructions.  This pass does not
 modify the CFG. This pass is where algebraic simplification happens.
 
 This pass combines things like:
 
 .. code-block:: llvm
 

 runtime library functions).  For example, a call ``exit(3)`` that occurs within
 the ``main()`` function can be transformed into simply ``return 3``. Whether or
 not library calls are simplified is controlled by the
 :ref:`-function-attrs <passes-function-attrs>` pass and LLVM's knowledge of
 library calls on different targets.
 
 .. _passes-aggressive-instcombine:
 
-``-aggressive-instcombine``: Combine expression patterns
+``aggressive-instcombine``: Combine expression patterns
 --------------------------------------------------------
 
 Combine expression patterns to form expressions with fewer, simple instructions.
 
 For example, this pass reduce width of expressions post-dominated by TruncInst
 into smaller width when applicable.
 
 It differs from instcombine pass in that it can modify CFG and contains pattern
 optimization that requires higher complexity than the O(1), thus, it should run fewer
 times than instcombine pass.
 
-``-internalize``: Internalize Global Symbols
---------------------------------------------
+``internalize``: Internalize Global Symbols
+-------------------------------------------
 
 This pass loops over all of the functions in the input module, looking for a
 main function.  If a main function is found, all other functions and all global
 variables with initializers are marked as internal.
 
-``-ipsccp``: Interprocedural Sparse Conditional Constant Propagation
---------------------------------------------------------------------
+``ipsccp``: Interprocedural Sparse Conditional Constant Propagation
+-------------------------------------------------------------------
 
 An interprocedural variant of :ref:`Sparse Conditional Constant Propagation
 <passes-sccp>`.
 
-``-jump-threading``: Jump Threading
------------------------------------
+``jump-threading``: Jump Threading
+----------------------------------
 
 Jump threading tries to find distinct threads of control flow running through a
 basic block.  This pass looks at blocks that have multiple predecessors and
 multiple successors.  If one or more of the predecessors of the block can be
 proven to always cause a jump to one of the successors, we forward the edge
 from the predecessor to the successor by duplicating the contents of this
 block.
 
 An example of when this can occur is code like this:
 
 .. code-block:: c++
 
   if () { ...
     X = 4;
   }
   if (X < 3) {
 
 In this case, the unconditional branch at the end of the first if can be
 revectored to the false side of the second if.
 
 .. _passes-lcssa:
 
-``-lcssa``: Loop-Closed SSA Form Pass
--------------------------------------
+``lcssa``: Loop-Closed SSA Form Pass
+------------------------------------
 
 This pass transforms loops by placing phi nodes at the end of the loops for all
 values that are live across the loop boundary.  For example, it turns the left
 into the right code:
 
 .. code-block:: c++
 
   for (...)                for (...)
       if (c)                   if (c)
           X1 = ...                 X1 = ...
       else                     else
           X2 = ...                 X2 = ...
       X3 = phi(X1, X2)         X3 = phi(X1, X2)
   ... = X3 + 4              X4 = phi(X3)
                               ... = X4 + 4
 
 This is still valid LLVM; the extra phi nodes are purely redundant, and will be
 trivially eliminated by ``InstCombine``.  The major benefit of this
 transformation is that it makes many other loop optimizations, such as
 ``LoopUnswitch``\ ing, simpler. You can read more in the
 :ref:`loop terminology section for the LCSSA form <loop-terminology-lcssa>`.
 
 .. _passes-licm:
 
-``-licm``: Loop Invariant Code Motion
--------------------------------------
+``licm``: Loop Invariant Code Motion
+------------------------------------
 
 This pass performs loop invariant code motion, attempting to remove as much
 code from the body of a loop as possible.  It does this by either hoisting code
 into the preheader block, or by sinking code to the exit blocks if it is safe.
 This pass also promotes must-aliased memory locations in the loop to live in
 registers, thus hoisting and sinking "invariant" loads and stores.
 
 Hoisting operations out of loops is a canonicalization transform. It enables
#. Scalar Promotion of Memory.  If there is a store instruction inside of the
    #. There are no stores or loads in the loop which *may* alias the pointer.
       There are no calls in the loop which mod/ref the pointer.
 
    If these conditions are true, we can promote the loads and stores in the
    loop of the pointer to use a temporary alloca'd variable.  We then use the
    :ref:`mem2reg <passes-mem2reg>` functionality to construct the appropriate
    SSA form for the variable.
 
-``-loop-deletion``: Delete dead loops
--------------------------------------
+``loop-deletion``: Delete dead loops
+------------------------------------
 
 This file implements the Dead Loop Deletion Pass.  This pass is responsible for
 eliminating loops with non-infinite computable trip counts that have no side
 effects or volatile instructions, and do not contribute to the computation of
 the function's return value.
 
 .. _passes-loop-extract:
 
-``-loop-extract``: Extract loops into new functions
----------------------------------------------------
+``loop-extract``: Extract loops into new functions
+--------------------------------------------------
 
 A pass wrapper around the ``ExtractLoop()`` scalar transformation to extract
 each top-level loop into its own new function.  If the loop is the *only* loop
 in a given function, it is not touched.  This is a pass most useful for
 debugging via bugpoint.
 
-``-loop-extract-single``: Extract at most one loop into a new function
-----------------------------------------------------------------------
-
-Similar to :ref:`Extract loops into new functions <passes-loop-extract>`, this
-pass extracts one natural loop from the program into a function if it can.
-This is used by :program:`bugpoint`.
-
-``-loop-reduce``: Loop Strength Reduction
------------------------------------------
+``loop-reduce``: Loop Strength Reduction
+----------------------------------------
 
 This pass performs a strength reduction on array references inside loops that
 have as one or more of their components the loop induction variable.  This is
 accomplished by creating a new value to hold the initial value of the array
 access for the first iteration, and then creating a new GEP instruction in the
 loop to increment the value by the appropriate amount.
 
 .. _passes-loop-rotate:
 
-``-loop-rotate``: Rotate Loops
-------------------------------
+``loop-rotate``: Rotate Loops
+-----------------------------
 
 A simple loop rotation transformation.  A summary of it can be found in
 :ref:`Loop Terminology for Rotated Loops <loop-terminology-loop-rotate>`.
 
 
 .. _passes-loop-simplify:
 
-``-loop-simplify``: Canonicalize natural loops
-----------------------------------------------
+``loop-simplify``: Canonicalize natural loops
+---------------------------------------------
 
 This pass performs several transformations to transform natural loops into a
 simpler form, which makes subsequent analyses and transformations simpler and
 more effective. A summary of it can be found in
 :ref:`Loop Terminology, Loop Simplify Form <loop-terminology-loop-simplify>`.
 
 Loop pre-header insertion guarantees that there is a single, non-critical entry
 edge from outside of the loop to the loop header.  This simplifies a number of

 
 Note that the :ref:`simplifycfg <passes-simplifycfg>` pass will clean up blocks
 which are split out but end up being unnecessary, so usage of this pass should
 not pessimize generated code.
 
 This pass obviously modifies the CFG, but updates loop information and
 dominator information.
 
-``-loop-unroll``: Unroll loops
-------------------------------
+``loop-unroll``: Unroll loops
+-----------------------------
 
 This pass implements a simple loop unroller.  It works best when loops have
 been canonicalized by the :ref:`indvars <passes-indvars>` pass, allowing it to
 determine the trip counts of loops easily.
 
-``-loop-unroll-and-jam``: Unroll and Jam loops
-----------------------------------------------
+``loop-unroll-and-jam``: Unroll and Jam loops
+---------------------------------------------
 
 This pass implements a simple unroll and jam classical loop optimisation pass.
 It transforms loop from:
 
 .. code-block:: c++
 
   for i.. i+= 1              for i.. i+= 4
     for j..                    for j..
       code(i, j)                 code(i, j)
                                  code(i+1, j)
                                  code(i+2, j)
                                  code(i+3, j)
                              remainder loop
 
 Which can be seen as unrolling the outer loop and "jamming" (fusing) the inner
 loops into one. When variables or loads can be shared in the new inner loop, this
 can lead to significant performance improvements. It uses
 :ref:`Dependence Analysis <passes-da>` for proving the transformations are safe.
 
-.. _passes-loop-unswitch:
-
-``-loop-unswitch``: Unswitch loops
-----------------------------------
-
-This pass transforms loops that contain branches on loop-invariant conditions
-to have multiple loops.  For example, it turns the left into the right code:
-
-.. code-block:: c++
-
-  for (...)                  if (lic)
-      A                          for (...)
-      if (lic)                       A; B; C
-          B                  else
-      C                          for (...)
-                                     A; C
-
-This can increase the size of the code exponentially (doubling it every time a
-loop is unswitched) so we only unswitch if the resultant code will be smaller
-than a threshold.
-
-This pass expects :ref:`LICM <passes-licm>` to be run before it to hoist
-invariant conditions out of the loop, to make the unswitching opportunity
-obvious.
-
-``-lower-global-dtors``: Lower global destructors
-------------------------------------------------------------
+``lower-global-dtors``: Lower global destructors
+------------------------------------------------
 
 This pass lowers global module destructors (``llvm.global_dtors``) by creating
 wrapper functions that are registered as global constructors in
 ``llvm.global_ctors`` and which contain a call to ``__cxa_atexit`` to register
 their destructor functions.
 
-``-loweratomic``: Lower atomic intrinsics to non-atomic form
-------------------------------------------------------------
+``loweratomic``: Lower atomic intrinsics to non-atomic form
+-----------------------------------------------------------
 
 This pass lowers atomic intrinsics to non-atomic form for use in a known
 non-preemptible environment.
 
 The pass does not verify that the environment is non-preemptible (in general
 this would require knowledge of the entire call graph of the program including
 any libraries which may not be available in bitcode form); it simply lowers
 every atomic intrinsic.
 
-``-lowerinvoke``: Lower invokes to calls, for unwindless code generators
-------------------------------------------------------------------------
+``lowerinvoke``: Lower invokes to calls, for unwindless code generators
+-----------------------------------------------------------------------
 
 This transformation is designed for use by code generators which do not yet
 support stack unwinding.  This pass converts ``invoke`` instructions to
 ``call`` instructions, so that any exception-handling ``landingpad`` blocks
 become dead code (which can be removed by running the ``-simplifycfg`` pass
 afterwards).
 
-``-lowerswitch``: Lower ``SwitchInst``\ s to branches
------------------------------------------------------
+``lowerswitch``: Lower ``SwitchInst``\ s to branches
+----------------------------------------------------
 
 Rewrites switch instructions with a sequence of branches, which allows targets
 to get away with not implementing the switch instruction until it is
 convenient.
 
 .. _passes-mem2reg:
 
-``-mem2reg``: Promote Memory to Register
-----------------------------------------
+``mem2reg``: Promote Memory to Register
+---------------------------------------
 
 This file promotes memory references to be register references.  It promotes
 alloca instructions which only have loads and stores as uses.  An ``alloca`` is
 transformed by using dominator frontiers to place phi nodes, then traversing
 the function in depth-first order to rewrite loads and stores as appropriate.
 This is just the standard SSA construction algorithm to construct "pruned" SSA
 form.
 
-``-memcpyopt``: MemCpy Optimization
------------------------------------
+``memcpyopt``: MemCpy Optimization
+----------------------------------
 
 This pass performs various transformations related to eliminating ``memcpy``
 calls, or transforming sets of stores into ``memset``\ s.
 
-``-mergefunc``: Merge Functions
--------------------------------
+``mergefunc``: Merge Functions
+------------------------------
 
 This pass looks for equivalent functions that are mergeable and folds them.
 
 Total-ordering is introduced among the functions set: we define comparison
 that answers for every two functions which of them is greater. It allows to
 arrange functions into the binary tree.
 
 For every new function we check for equivalent in tree.
 
 If equivalent exists we fold such functions. If both functions are overridable,
 we move the functionality into a new internal function and leave two
 overridable thunks to it.
 
 If there is no equivalent, then we add this function to tree.
 
 Lookup routine has O(log(n)) complexity, while whole merging process has
 complexity of O(n*log(n)).
 
 Read
 :doc:`this <MergeFunctions>`
 article for more details.
 
-``-mergereturn``: Unify function exit nodes
--------------------------------------------
+``mergereturn``: Unify function exit nodes
+------------------------------------------
 
 Ensure that functions have at most one ``ret`` instruction in them.
 Additionally, it keeps track of which node is the new exit node of the CFG.
 
-``-partial-inliner``: Partial Inliner
--------------------------------------
+``partial-inliner``: Partial Inliner
+------------------------------------
 
 This pass performs partial inlining, typically by inlining an ``if`` statement
 that surrounds the body of the function.
 
-``-prune-eh``: Remove unused exception handling info
-----------------------------------------------------
-
-This file implements a simple interprocedural pass which walks the call-graph,
-turning invoke instructions into call instructions if and only if the callee
-cannot throw an exception.  It implements this as a bottom-up traversal of the
-call-graph.
-
-``-reassociate``: Reassociate expressions
------------------------------------------
+``reassociate``: Reassociate expressions
+----------------------------------------
 
 This pass reassociates commutative expressions in an order that is designed to
 promote better constant propagation, GCSE, :ref:`LICM <passes-licm>`, PRE, etc.
 
 For example: 4 + (x + 5) ⇒ x + (4 + 5)
 
 In the implementation of this algorithm, constants are assigned rank = 0,
 function arguments are rank = 1, and other values are assigned ranks
 corresponding to the reverse post order traversal of current function (starting
 at 2), which effectively gives values in deep loops higher rank than values not
 in loops.
 
-``-rel-lookup-table-converter``: Relative lookup table converter
-----------------------------------------------------------------
+``rel-lookup-table-converter``: Relative lookup table converter
+---------------------------------------------------------------
 
 This pass converts lookup tables to PIC-friendly relative lookup tables.
 
-``-reg2mem``: Demote all values to stack slots
-----------------------------------------------
+``reg2mem``: Demote all values to stack slots
+---------------------------------------------
 
 This file demotes all registers to memory references.  It is intended to be the
 inverse of :ref:`mem2reg <passes-mem2reg>`.  By converting to ``load``
 instructions, the only values live across basic blocks are ``alloca``
 instructions and ``load`` instructions before ``phi`` nodes.  It is intended
 that this should make CFG hacking much easier.  To make later hacking easier,
 the entry block is split into two, such that all introduced ``alloca``
 instructions (and nothing else) are in the entry block.
 
-``-sroa``: Scalar Replacement of Aggregates
-------------------------------------------------------
+``sroa``: Scalar Replacement of Aggregates
+------------------------------------------
 
 The well-known scalar replacement of aggregates transformation.  This transform
 breaks up ``alloca`` instructions of aggregate type (structure or array) into
 individual ``alloca`` instructions for each member if possible.  Then, if
 possible, it transforms the individual ``alloca`` instructions into nice clean
 scalar SSA form.
 
 .. _passes-sccp:
 
-``-sccp``: Sparse Conditional Constant Propagation
---------------------------------------------------
+``sccp``: Sparse Conditional Constant Propagation
+-------------------------------------------------
 
 Sparse conditional constant propagation and merging, which can be summarized
 as:
 
 * Assumes values are constant unless proven otherwise
 * Assumes BasicBlocks are dead unless proven otherwise
 * Proves values to be constant, and replaces them with constants
 * Proves conditional branches to be unconditional
 
 Note that this pass has a habit of making definitions be dead.  It is a good
 idea to run a :ref:`DCE <passes-dce>` pass sometime after running this pass.
 
 .. _passes-simplifycfg:
 
-``-simplifycfg``: Simplify the CFG
-----------------------------------
+``simplifycfg``: Simplify the CFG
+---------------------------------
 
 Performs dead code elimination and basic block merging.  Specifically:
 
 * Removes basic blocks with no predecessors.
 * Merges a basic block into its predecessor if there is only one and the
   predecessor only has one successor.
 * Eliminates PHI nodes for basic blocks with a single predecessor.
 * Eliminates a basic block that only contains an unconditional branch.
 
-``-sink``: Code sinking
------------------------
+``sink``: Code sinking
+----------------------
 
 This pass moves instructions into successor blocks, when possible, so that they
 aren't executed on paths where their results aren't needed.
 
-``-strip``: Strip all symbols from a module
--------------------------------------------
+``strip``: Strip all symbols from a module
+------------------------------------------
 
 Performs code stripping.  This transformation can delete:
 
 * names for virtual registers
 * symbols for internal globals and functions
 * debug information
 
 Note that this transformation makes code much less readable, so it should only
 be used in situations where the strip utility would be used, such as reducing
 code size or making it harder to reverse engineer code.
 
-``-strip-dead-debug-info``: Strip debug info for unused symbols
----------------------------------------------------------------
+``strip-dead-debug-info``: Strip debug info for unused symbols
+--------------------------------------------------------------
 
 .. FIXME: this description is the same as for -strip
 
 performs code stripping. this transformation can delete:
 
 * names for virtual registers
 * symbols for internal globals and functions
 * debug information
 
 note that this transformation makes code much less readable, so it should only
 be used in situations where the strip utility would be used, such as reducing
 code size or making it harder to reverse engineer code.
 
-``-strip-dead-prototypes``: Strip Unused Function Prototypes
-------------------------------------------------------------
+``strip-dead-prototypes``: Strip Unused Function Prototypes
+-----------------------------------------------------------
 
 This pass loops over all of the functions in the input module, looking for dead
 declarations and removes them.  Dead declarations are declarations of functions
 for which no implementation is available (i.e., declarations for unused library
 functions).
 
-``-strip-debug-declare``: Strip all ``llvm.dbg.declare`` intrinsics
--------------------------------------------------------------------
+``strip-debug-declare``: Strip all ``llvm.dbg.declare`` intrinsics
+------------------------------------------------------------------
 
 .. FIXME: this description is the same as for -strip
 
 This pass implements code stripping.  Specifically, it can delete:
 
 #. names for virtual registers
 #. symbols for internal globals and functions
 #. debug information
 
 Note that this transformation makes code much less readable, so it should only
 be used in situations where the 'strip' utility would be used, such as reducing
 code size or making it harder to reverse engineer code.
 
-``-strip-nondebug``: Strip all symbols, except dbg symbols, from a module
--------------------------------------------------------------------------
+``strip-nondebug``: Strip all symbols, except dbg symbols, from a module
+------------------------------------------------------------------------
 
 .. FIXME: this description is the same as for -strip
 
 This pass implements code stripping.  Specifically, it can delete:
 
 #. names for virtual registers
 #. symbols for internal globals and functions
 #. debug information
 
 Note that this transformation makes code much less readable, so it should only
 be used in situations where the 'strip' utility would be used, such as reducing
 code size or making it harder to reverse engineer code.
 
-``-tailcallelim``: Tail Call Elimination
-----------------------------------------
+``tailcallelim``: Tail Call Elimination
+---------------------------------------
 
 This file transforms calls of the current function (self recursion) followed by
 a return instruction with a branch to the entry of the function, creating a
 loop.  This pass also implements the following extensions to the basic
 algorithm:
 
 #. Trivial instructions between the call and return do not prevent the
    transformation from taking place, though currently the analysis cannot

 #. If it can prove that callees do not access their caller stack frame, they
    are marked as eligible for tail call elimination (by the code generator).
 
 Utility Passes
 ==============
 
 This section describes the LLVM Utility Passes.
 
-``-deadarghaX0r``: Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)
-------------------------------------------------------------------------
+``deadarghaX0r``: Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)
+-----------------------------------------------------------------------
 
 Same as dead argument elimination, but deletes arguments to functions which are
 external.  This is only for use by :doc:`bugpoint <Bugpoint>`.
 
-``-extract-blocks``: Extract Basic Blocks From Module (for bugpoint use)
-------------------------------------------------------------------------
+``extract-blocks``: Extract Basic Blocks From Module (for bugpoint use)
+-----------------------------------------------------------------------
 
 This pass is used by bugpoint to extract all blocks from the module into their
 own functions.
 
-``-instnamer``: Assign names to anonymous instructions
-------------------------------------------------------
+``instnamer``: Assign names to anonymous instructions
+-----------------------------------------------------
 
 This is a little utility pass that gives instructions names, this is mostly
 useful when diffing the effect of an optimization because deleting an unnamed
 instruction can change all other instruction numbering, making the diff very
 noisy.
 
 .. _passes-verify:
 
-``-verify``: Module Verifier
-----------------------------
+``verify``: Module Verifier
+---------------------------
 
 Verifies an LLVM IR code.  This is useful to run after an optimization which is
 undergoing testing.  Note that llvm-as verifies its input before emitting
 bitcode, and also that malformed bitcode is likely to make LLVM crash.  All
 language front-ends are therefore encouraged to verify their output before
 performing optimizing transformations.
 
 #. Both of a binary operator's parameters are of the same type.

 #. Function call argument types match the function prototype.
 #. All other things that are tested by asserts spread about the code.
 
 Note that this does not provide full security verification (like Java), but
 instead just tries to ensure that code is well-formed.
 
 .. _passes-view-cfg:
 
-``-view-cfg``: View CFG of function
------------------------------------
+``view-cfg``: View CFG of function
+----------------------------------
 
 Displays the control flow graph using the GraphViz tool.
 Additionally the ``-cfg-func-name=<substring>`` option can be used to filter the
 functions that are displayed. All functions that contain the specified substring
 will be displayed.
 
-``-view-cfg-only``: View CFG of function (with no function bodies)
-------------------------------------------------------------------
+``view-cfg-only``: View CFG of function (with no function bodies)
+-----------------------------------------------------------------
 
 Displays the control flow graph using the GraphViz tool, but omitting function
 bodies.
 Additionally the ``-cfg-func-name=<substring>`` option can be used to filter the
 functions that are displayed. All functions that contain the specified substring
 will be displayed.
 
-``-view-dom``: View dominance tree of function
-----------------------------------------------
+``view-dom``: View dominance tree of function
+---------------------------------------------
 
 Displays the dominator tree using the GraphViz tool.
 
-``-view-dom-only``: View dominance tree of function (with no function bodies)
------------------------------------------------------------------------------
+``view-dom-only``: View dominance tree of function (with no function bodies)
+----------------------------------------------------------------------------
 
 Displays the dominator tree using the GraphViz tool, but omitting function
 bodies.
 
-``-view-postdom``: View postdominance tree of function
+``view-post-dom``: View postdominance tree of function
 ------------------------------------------------------
 
 Displays the post dominator tree using the GraphViz tool.
 
-``-view-postdom-only``: View postdominance tree of function (with no function bodies)
+``view-post-dom-only``: View postdominance tree of function (with no function bodies)
 -------------------------------------------------------------------------------------
 
 Displays the post dominator tree using the GraphViz tool, but omitting function
 bodies.
 
-``-transform-warning``: Report missed forced transformations
-------------------------------------------------------------
+``transform-warning``: Report missed forced transformations
+-----------------------------------------------------------
 
 Emits warnings about not yet applied forced transformations (e.g. from
 ``#pragma omp simd``).