From 5c60386dbc74f1e5e30ead158708fac02fedbb40 Mon Sep 17 00:00:00 2001 From: Duncan Sands Date: Tue, 6 Jul 2010 15:52:15 +0000 Subject: Bring the list of passes and their descriptions up to date. Patch by Kenneth Hoste. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@107669 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/Passes.html | 701 ++++++++++++++++++++++++++++++++++++++++++------------- 1 file changed, 539 insertions(+), 162 deletions(-) (limited to 'docs') diff --git a/docs/Passes.html b/docs/Passes.html index 8b9bd07f11..fb3bc9474b 100644 --- a/docs/Passes.html +++ b/docs/Passes.html @@ -27,7 +27,7 @@ while () { my $o = $order{$1}; $o = "000" unless defined $o; push @x, "$o-$1$2\n"; - push @y, "$o $2\n"; + push @y, "$o -$1: $2\n"; } @x = map { s/^\d\d\d//; $_ } sort @x; @y = map { s/^\d\d\d//; $_ } sort @y; @@ -91,29 +91,46 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if ! -dot-postdom-onlyPrint post dominator tree of function to 'dot' file (with no function bodies) -globalsmodref-aaSimple mod/ref analysis for globals -instcountCounts the various types of Instructions +-interprocedural-aa-evalExhaustive Interprocedural Alias Analysis Precision Evaluator +-interprocedural-basic-aaInterprocedural Basic Alias Analysis -intervalsInterval Partition Construction --loopsNatural Loop Construction +-iv-usersInduction Variable Users +-lazy-value-infoLazy Value Information Analysis +-ldaLoop Dependence Analysis +-libcall-aaLibCall Alias Analysis +-lintCheck for common errors in LLVM IR +-live-valuesValue Liveness Analysis +-loopsNatural Loop Information -memdepMemory Dependence Analysis +-module-debuginfoPrints module debug info metadata -no-aaNo Alias Analysis (always returns 'may' alias) -no-profileNo Profile Information +-pointertrackingTrack pointer bounds -postdomfrontierPost-Dominance Frontier Construction -postdomtreePost-Dominator Tree Construction -print-alias-setsAlias Set Printer -print-callgraphPrint a call graph -print-callgraph-sccsPrint SCCs of the Call Graph -print-cfg-sccsPrint SCCs of each function CFG +-print-dbginfoPrint debug info in human readable form +-print-dom-infoDominator Info Printer -print-externalfnconstantsPrint external fn callsites passed constants -print-functionPrint function to stderr -print-modulePrint module to stderr -print-used-typesFind Used Types +-profile-estimatorEstimate profiling information -profile-loaderLoad profile information from llvmprof.out +-profile-verifierVerify profiling information -scalar-evolutionScalar Evolution Analysis +-scev-aaScalarEvolution-based Alias Analysis -targetdataTarget Data Layout TRANSFORM PASSES OptionName +-abcdRemove redundant conditional branches -adceAggressive Dead Code Elimination +-always-inlineInliner for always_inline functions -argpromotionPromote 'by reference' arguments to scalars -block-placementProfile Guided Basic Block Placement -break-crit-edgesBreak critical edges in CFG @@ -125,16 +142,14 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if ! -deadtypeelimDead Type Elimination -dieDead Instruction Elimination -dseDead Store Elimination +-functionattrsDeduce function attributes -globaldceDead Global Elimination -globaloptGlobal Variable Optimizer -gvnGlobal Value Numbering -indvarsCanonicalize Induction Variables -inlineFunction Integration/Inlining --insert-block-profilingInsert instrumentation for block profiling -insert-edge-profilingInsert instrumentation for edge profiling --insert-function-profilingInsert instrumentation for function profiling --insert-null-profiling-rsMeasure profiling framework overhead --insert-rs-profiling-frameworkInsert random sampling instrumentation framework +-insert-optimal-edge-profilingInsert optimal instrumentation for edge profiling -instcombineCombine redundant instructions -internalizeInternalize Global Symbols -ipconstpropInterprocedural constant propagation @@ -156,16 +171,27 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if ! -lowerswitchLower SwitchInst's to branches -mem2regPromote Memory to Register -memcpyoptOptimize use of memcpy and friends +-mergefuncMerge Functions -mergereturnUnify function exit nodes +-partial-inlinerPartial Inliner +-partialspecializationPartial Specialization -prune-ehRemove unused exception handling info -reassociateReassociate expressions -reg2memDemote all values to stack slots -scalarreplScalar Replacement of Aggregates -sccpSparse Conditional Constant Propagation +-sinkCode Sinking -simplify-libcallsSimplify well-known library calls +-simplify-libcalls-halfpowrSimplify half_powr library calls -simplifycfgSimplify the CFG +-split-gepsSplit complex GEPs into simple GEPs +-ssiStatic Single Information Construction +-ssi-everythingStatic Single Information Construction (everything, intended for debugging) -stripStrip all symbols from a module +-strip-dead-debug-infoStrip debug info for unused symbols -strip-dead-prototypesRemove unused function declarations +-strip-debug-declareStrip all llvm.dbg.declare intrinsics +-strip-nondebugStrip all symbols, except dbg symbols, from a module -sretpromotionPromote sret arguments -tailcallelimTail Call Elimination -tailduplicateTail Duplication @@ -175,6 +201,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if ! OptionName -deadarghaX0rDead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE) -extract-blocksExtract Basic Blocks From Module (for bugpoint use) +-instnamerAssign names to anonymous instructions -preverifyPreliminary module verification -verifyModule Verifier -view-cfgView CFG of function @@ -194,7 +221,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Exhaustive Alias Analysis Precision Evaluator + -aa-eval: Exhaustive Alias Analysis Precision Evaluator

This is a simple N^2 alias analysis accuracy evaluator. @@ -208,7 +235,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Basic Alias Analysis (default AA impl) + -basicaa: Basic Alias Analysis (default AA impl)

@@ -220,7 +247,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Basic CallGraph Construction + -basiccg: Basic CallGraph Construction

Yet to be written.

@@ -228,7 +255,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Optimize for code generation + -codegenprepare: Optimize for code generation

@@ -240,7 +267,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Count Alias Analysis Query Responses + -count-aa: Count Alias Analysis Query Responses

@@ -251,7 +278,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- AA use debugger + -debug-aa: AA use debugger

@@ -268,7 +295,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dominance Frontier Construction + -domfrontier: Dominance Frontier Construction

@@ -279,7 +306,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dominator Tree Construction + -domtree: Dominator Tree Construction

@@ -290,7 +317,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print Call Graph to 'dot' file + -dot-callgraph: Print Call Graph to 'dot' file

@@ -302,7 +329,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print CFG of function to 'dot' file + -dot-cfg: Print CFG of function to 'dot' file

@@ -314,7 +341,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- 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)

@@ -327,7 +354,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print dominator tree of function to 'dot' file + -dot-dom: Print dominator tree of function to 'dot' file

@@ -339,7 +366,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print dominator tree of function to 'dot' file (with no + -dot-dom-only: Print dominator tree of function to 'dot' file (with no function bodies)
@@ -353,7 +380,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print post dominator tree of function to 'dot' file + dot-postdom: Print post dominator tree of function to 'dot' file

@@ -365,7 +392,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print post dominator tree of function to 'dot' file + dot-postdom-only: Print post dominator tree of function to 'dot' file (with no function bodies)
@@ -379,7 +406,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Simple mod/ref analysis for globals + -globalsmodref-aa: Simple mod/ref analysis for globals

@@ -392,7 +419,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Counts the various types of Instructions + -instcount: Counts the various types of Instructions

@@ -402,7 +429,30 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Interval Partition Construction + -interprocedural-aa-eval: Exhaustive Interprocedural Alias Analysis Precision Evaluator +
+
+

This pass implements 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. +

+
+ + +
+ -interprocedural-basic-aa: Interprocedural Basic Alias Analysis +
+
+

This pass defines the default implementation of the Alias Analysis interface + that simply implements a few identities (two different globals cannot alias, + etc), but otherwise does no analysis. +

+
+ + +
+ -intervals: Interval Partition Construction

@@ -418,7 +468,80 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Natural Loop Construction + -iv-users: Induction Variable Users +
+
+

Bookkeeping for "interesting" users of expressions computed from + induction variables.

+
+ + +
+ -lazy-value-info: Lazy Value Information Analysis +
+
+

Interface for lazy computation of value constraint information.

+
+ + +
+ -lda: Loop Dependence Analysis +
+
+

Loop dependence analysis framework, which is used to detect dependences in + memory accesses in loops.

+
+ + +
+ -libcall-aa: LibCall Alias Analysis +
+
+

LibCall Alias Analysis.

+
+ + +
+ -lint: Check for common errors in 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 statically. This pass does no dynamic instrumentation, so it + can't check for all possible problems.

+ +

Another limitation is that it assumes all code will be executed. A store + through a null pointer in a basic block which is never reached is harmless, + but this pass will warn about it anyway.

+ +

Optimization passes may make conditions that this pass checks for more or + less obvious. If an optimization pass appears to be introducing a warning, + it may be that the optimization pass is merely exposing an existing + condition in the code.

+ +

This code may be run before 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. +

+
+ + +
+ -live-values: Values Liveness Analysis +
+
+

LLVM IR Value liveness analysis pass.

+
+ + +
+ -loops: Natural Loop Construction

@@ -431,7 +554,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Memory Dependence Analysis + -memdep: Memory Dependence Analysis

@@ -444,7 +567,20 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- No Alias Analysis (always returns 'may' alias) + -module-debuginfo: Prints module debug info metadata +
+
+

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. +

+
+ + +
+ -no-aa: No Alias Analysis (always returns 'may' alias)

@@ -456,7 +592,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- No Profile Information + -no-profile: No Profile Information

@@ -467,7 +603,16 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Post-Dominance Frontier Construction + -pointertracking: Track pointer bounds. +
+
+

Tracking of pointer bounds. +

+
+ + +
+ -postdomfrontier: Post-Dominance Frontier Construction

@@ -478,7 +623,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Post-Dominator Tree Construction + -postdomtree: Post-Dominator Tree Construction

@@ -489,7 +634,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Alias Set Printer + -print-alias-sets: Alias Set Printer

Yet to be written.

@@ -497,7 +642,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print a call graph + -print-callgraph: Print a call graph

@@ -508,7 +653,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print SCCs of the Call Graph + -print-callgraph-sccs: Print SCCs of the Call Graph

@@ -519,7 +664,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print SCCs of each function CFG + -print-cfg-sccs: Print SCCs of each function CFG

@@ -530,7 +675,31 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print external fn callsites passed constants + -print-dbginfo: Print debug info in human readable form +
+
+

Pass that prints instructions, and associated debug info: +

    + +
  • source/line/col information
    • +
  • original variable name
    • +
  • original type name
    • +
+ +

+
+ + +
+ -print-dom-info: Dominator Info Printer +
+
+

Dominator Info Printer.

+
+ + +
+ -print-externalfnconstants: Print external fn callsites passed constants

@@ -543,7 +712,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print function to stderr + -print-function: Print function to stderr

@@ -555,7 +724,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Print module to stderr + -print-module: Print module to stderr

@@ -565,7 +734,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Find Used Types + -print-used-types: Find Used Types

@@ -576,7 +745,17 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Load profile information from llvmprof.out + -profile-estimator: Estimate profiling information +
+
+

Profiling information that estimates the profiling information + in a very crude and unimaginative way. +

+
+ + +
+ -profile-loader: Load profile information from llvmprof.out

@@ -587,7 +766,15 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Scalar Evolution Analysis + -profile-verifier: Verify profiling information +
+
+

Pass that checks profiling information for plausibility.

+
+ + +
+ -scalar-evolution: Scalar Evolution Analysis

@@ -606,7 +793,45 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Target Data Layout + -scev-aa: +
+
+

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. +

+
+ + +
+ -strip-dead-debug-info: Strip debug info for unused symbols +
+
+

+ performs code stripping. this transformation can delete: +

+ +
    +
  1. names for virtual registers
    2. +
  2. symbols for internal globals and functions
    3. +
  3. debug information
    4. +
+ +

+ 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. +

+
+ + +
+ -targetdata: Target Data Layout

Provides other passes access to information on how the size and alignment @@ -621,7 +846,22 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Aggressive Dead Code Elimination + -abcd: Remove redundant conditional branches +
+
+

ABCD removes conditional branch instructions that can be proved redundant. + With the SSI representation, each variable has a constraint. By analyzing these + constraints we can prove that a branch is redundant. When a branch is proved + redundant it means that one direction will always be taken; thus, we can change + this branch into an unconditional jump.

+

It is advisable to run SimplifyCFG and + Aggressive Dead Code Elimination after ABCD + to clean up the code.

+
+ + +
+ -adce: Aggressive Dead Code Elimination

ADCE aggressively tries to eliminate code. This pass is similar to @@ -632,7 +872,16 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Promote 'by reference' arguments to scalars + -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

@@ -663,7 +912,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Profile Guided Basic Block Placement + -block-placement: Profile Guided Basic Block Placement

This pass is a very simple profile guided basic block placement algorithm. @@ -675,7 +924,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Break critical edges in CFG + -break-crit-edges: Break critical edges in CFG

@@ -688,7 +937,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Prepare a function for code generation + -codegenprepare: Prepare a function for code generation
This pass munges the code in the input function to better prepare it for @@ -698,7 +947,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Merge Duplicate Global Constants + -constmerge: Merge Duplicate Global Constants

@@ -711,7 +960,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Simple constant propagation + -constprop: Simple constant propagation

This file implements constant propagation and merging. It looks for @@ -727,7 +976,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dead Code Elimination + -dce: Dead Code Elimination

@@ -739,7 +988,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dead Argument Elimination + -deadargelim: Dead Argument Elimination

@@ -757,7 +1006,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dead Type Elimination + -deadtypeelim: Dead Type Elimination

@@ -769,7 +1018,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dead Instruction Elimination + -die: Dead Instruction Elimination

@@ -780,7 +1029,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dead Store Elimination + -dse: Dead Store Elimination

@@ -791,7 +1040,22 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Dead Global Elimination + -functionattrs: 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

@@ -805,7 +1069,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Global Variable Optimizer + -globalopt: Global Variable Optimizer

@@ -817,7 +1081,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Global Value Numbering + -gvn: Global Value Numbering

@@ -826,10 +1090,9 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

-
- Canonicalize Induction Variables + -indvars: Canonicalize Induction Variables

@@ -880,7 +1143,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Function Integration/Inlining + -inline: Function Integration/Inlining

@@ -890,26 +1153,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Insert instrumentation for block profiling -
-
-

- This pass instruments the specified program with counters for basic block - profiling, which counts the number of times each basic block executes. This - is the most basic form of profiling, which can tell which blocks are hot, but - cannot reliably detect hot paths through the CFG. -

- -

- Note that this implementation is very naïve. Control equivalent regions of - the CFG should not require duplicate counters, but it does put duplicate - counters in. -

-
- - -
- Insert instrumentation for edge profiling + -insert-edge-profiling: Insert instrumentation for edge profiling

@@ -927,51 +1171,18 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Insert instrumentation for function profiling + -insert-optimal-edge-profiling: Insert optimal instrumentation for edge profiling
-

- This pass instruments the specified program with counters for function - profiling, which counts the number of times each function is called. -

-
- - -
- Measure profiling framework overhead -
-
-

- The basic profiler that does nothing. It is the default profiler and thus - terminates RSProfiler chains. It is useful for measuring - framework overhead. -

-
- - -
- Insert random sampling instrumentation framework -
-
-

- The second stage of the random-sampling instrumentation framework, duplicates - all instructions in a function, ignoring the profiling code, then connects the - two versions together at the entry and at backedges. At each connection point - a choice is made as to whether to jump to the profiled code (take a sample) or - execute the unprofiled code. -

- -

- After this pass, it is highly recommended to runmem2reg - and adce. instcombine, - load-vn, gdce, and - dse also are good to run afterwards. +

This pass instruments the specified program with counters for edge profiling. + Edge profiling can give a reasonable approximation of the hot paths through a + program, and is used for a wide variety of program transformations.

- Combine redundant instructions + -instcombine: Combine redundant instructions

@@ -1025,7 +1236,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Internalize Global Symbols + -internalize: Internalize Global Symbols

@@ -1037,7 +1248,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Interprocedural constant propagation + -ipconstprop: Interprocedural constant propagation

@@ -1051,7 +1262,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Interprocedural Sparse Conditional Constant Propagation + -ipsccp: Interprocedural Sparse Conditional Constant Propagation

@@ -1062,7 +1273,7 @@ perl -e '$/ = undef; for (split(/\n/, <>)) { s:^ *///? ?::; print "

\n" if !

- Thread control through conditional blocks + -jump-threading: Thread control through conditional blocks

@@ -1091,7 +1302,7 @@ if (X < 3) {

- Loop-Closed SSA Form Pass + -lcssa: Loop-Closed SSA Form Pass

@@ -1120,7 +1331,7 @@ if (X < 3) {

- Loop Invariant Code Motion + -licm: Loop Invariant Code Motion

@@ -1156,7 +1367,7 @@ if (X < 3) {

- Dead Loop Deletion Pass + -loop-deletion: Dead Loop Deletion Pass

@@ -1169,7 +1380,7 @@ if (X < 3) {

- Extract loops into new functions + -loop-extract: Extract loops into new functions

@@ -1182,7 +1393,7 @@ if (X < 3) {

- Extract at most one loop into a new function + -loop-extract-single: Extract at most one loop into a new function

@@ -1194,7 +1405,7 @@ if (X < 3) {

- Index Split Loops + -loop-index-split: Index Split Loops

@@ -1205,7 +1416,7 @@ if (X < 3) {

- Loop Strength Reduction + -loop-reduce: Loop Strength Reduction

@@ -1219,7 +1430,7 @@ if (X < 3) {

- Rotate Loops + -loop-rotate: Rotate Loops

A simple loop rotation transformation.

@@ -1227,7 +1438,7 @@ if (X < 3) {
- Unroll loops + -loop-unroll: Unroll loops

@@ -1239,7 +1450,7 @@ if (X < 3) {

- Unswitch loops + -loop-unswitch: Unswitch loops

@@ -1269,7 +1480,7 @@ if (X < 3) {

- Canonicalize natural loops + -loopsimplify: Canonicalize natural loops

@@ -1310,7 +1521,23 @@ if (X < 3) {

- Lower invoke and unwind, for unwindless code generators + -lowerallocs: Lower allocations from instructions to calls +
+
+

+ Turn malloc and free instructions into @malloc and + @free calls. +

+ +

+ This is a target-dependent tranformation because it depends on the size of + data types and alignment constraints. +

+
+ + +
+ -lowerinvoke: Lower invoke and unwind, for unwindless code generators

@@ -1351,7 +1578,7 @@ if (X < 3) {

- Lower Set Jump + -lowersetjmp: Lower Set Jump

@@ -1380,7 +1607,7 @@ if (X < 3) {

- Lower SwitchInst's to branches + -lowerswitch: Lower SwitchInst's to branches

@@ -1392,7 +1619,7 @@ if (X < 3) {

- Promote Memory to Register + -mem2reg: Promote Memory to Register

@@ -1408,7 +1635,7 @@ if (X < 3) {

- Optimize use of memcpy and friend + -memcpyopt: Optimize use of memcpy and friend

@@ -1419,7 +1646,28 @@ if (X < 3) {

- Unify function exit nodes + -mergefunc: Merge Functions +
+
+

This pass looks for equivalent functions that are mergable and folds them. + + A hash is computed from the function, based on its type and number of + basic blocks. + + Once all hashes are computed, we perform an expensive equality comparison + on each function pair. This takes n^2/2 comparisons per bucket, so it's + important that the hash function be high quality. The equality comparison + iterates through each instruction in each basic block. + + When a match is found the functions are folded. If both functions are + overridable, we move the functionality into a new internal function and + leave two overridable thunks to it. +

+
+ + +
+ -mergereturn: Unify function exit nodes

@@ -1430,7 +1678,33 @@ if (X < 3) {

- Remove unused exception handling info + -partial-inliner: Partial Inliner +
+
+

This pass performs partial inlining, typically by inlining an if + statement that surrounds the body of the function. +

+
+ + +
+ -partialspecialization: Partial Specialization +
+
+

This pass finds function arguments that are often a common constant and + specializes a version of the called function for that constant. + + This pass simply does the cloning for functions it specializes. It depends + on IPSCCP and DAE to clean up the results. + + The initial heuristic favors constant arguments that are used in control + flow. +

+
+ + +
+ -prune-eh: Remove unused exception handling info

@@ -1443,7 +1717,7 @@ if (X < 3) {

- Reassociate expressions + -reassociate: Reassociate expressions

@@ -1466,7 +1740,7 @@ if (X < 3) {

- Demote all values to stack slots + -reg2mem: Demote all values to stack slots

@@ -1483,7 +1757,7 @@ if (X < 3) {

- Scalar Replacement of Aggregates + -scalarrepl: Scalar Replacement of Aggregates

@@ -1505,7 +1779,7 @@ if (X < 3) {

- Sparse Conditional Constant Propagation + -sccp: Sparse Conditional Constant Propagation

@@ -1528,7 +1802,17 @@ if (X < 3) {

- Simplify well-known library calls + -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. +

+
+ + +
+ -simplify-libcalls: Simplify well-known library calls

@@ -1541,7 +1825,17 @@ if (X < 3) {

- Simplify the CFG + -simplify-libcalls-halfpowr: Simplify half_powr library calls +
+
+

Simple pass that applies an experimental transformation on calls + to specific functions. +

+
+ + +
+ -simplifycfg: Simplify the CFG

@@ -1560,11 +1854,48 @@ if (X < 3) {

- Strip all symbols from a module + -split-geps: Split complex GEPs into simple GEPs +
+
+

This function breaks GEPs with more than 2 non-zero operands into smaller + GEPs each with no more than 2 non-zero operands. This exposes redundancy + between GEPs with common initial operand sequences. +

+
+ + +
+ -ssi: Static Single Information Construction +
+
+

This pass converts a list of variables to the Static Single Information + form. + + We are building an on-demand representation, that is, we do not convert + every single variable in the target function to SSI form. Rather, we receive + a list of target variables that must be converted. We also do not + completely convert a target variable to the SSI format. Instead, we only + change the variable in the points where new information can be attached + to its live range, that is, at branch points. +

+
+ + +
+ -ssi-everything: Static Single Information Construction (everything, intended for debugging) +
+
+

A pass that runs SSI on every non-void variable, intended for debugging. +

+
+ + +
+ -strip: Strip all symbols from a module

- Performs code stripping. This transformation can delete: + performs code stripping. this transformation can delete:

    @@ -1574,7 +1905,7 @@ if (X < 3) {

- Note that this transformation makes code much less readable, so it should + 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.

@@ -1582,7 +1913,7 @@ if (X < 3) {
- Remove unused function declarations + -strip-dead-prototypes: Remove unused function declarations

@@ -1595,7 +1926,41 @@ if (X < 3) {

- Promote sret arguments + -strip-debug-declare: Strip all llvm.dbg.declare intrinsics +
+
+

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 +
+
+

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. +

+
+ + +
+ -sretpromotion: Promote sret arguments

@@ -1618,7 +1983,7 @@ if (X < 3) {

- Tail Call Elimination + -tailcallelim: Tail Call Elimination

@@ -1650,7 +2015,7 @@ if (X < 3) {

- Tail Duplication + -tailduplicate: Tail Duplication

@@ -1670,7 +2035,7 @@ if (X < 3) {

- Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE) + -deadarghaX0r: Dead Argument Hacking (BUGPOINT USE ONLY; DO NOT USE)

@@ -1681,7 +2046,7 @@ if (X < 3) {

- Extract Basic Blocks From Module (for bugpoint use) + -extract-blocks: Extract Basic Blocks From Module (for bugpoint use)

@@ -1691,7 +2056,19 @@ if (X < 3) {

- Preliminary module verification + -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. +

+
+ + +
+ -preverify: Preliminary module verification

@@ -1707,7 +2084,7 @@ if (X < 3) {

- Module Verifier + -verify: Module Verifier

@@ -1758,7 +2135,7 @@ if (X < 3) {

- View CFG of function + -view-cfg: View CFG of function

@@ -1768,7 +2145,7 @@ if (X < 3) {

- View CFG of function (with no function bodies) + -view-cfg-only: View CFG of function (with no function bodies)

@@ -1779,7 +2156,7 @@ if (X < 3) {

- View dominator tree of function + -view-dom: View dominator tree of function

@@ -1789,7 +2166,7 @@ if (X < 3) {

- View dominator tree of function (with no function + -view-dom-only: View dominator tree of function (with no function bodies)
@@ -1802,7 +2179,7 @@ if (X < 3) {
- View post dominator tree of function + -view-postdom: View post dominator tree of function

@@ -1812,7 +2189,7 @@ if (X < 3) {

- View post dominator tree of function (with no + -view-postdom-only: View post dominator tree of function (with no function bodies)
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