llvm-mirror/lib/Analysis
Chandler Carruth 1d0b0955da Start removing the use of an ad-hoc 'never inline' set and instead
directly query the function information which this set was representing.
This simplifies the interface of the inline cost analysis, and makes the
always-inline pass significantly more efficient.

Previously, always-inline would first make a single set of every
function in the module *except* those marked with the always-inline
attribute. It would then query this set at every call site to see if the
function was a member of the set, and if so, refuse to inline it. This
is quite wasteful. Instead, simply check the function attribute directly
when looking at the callsite.

The normal inliner also had similar redundancy. It added every function
in the module with the noinline attribute to its set to ignore, even
though inside the cost analysis function we *already tested* the
noinline attribute and produced the same result.

The only tricky part of removing this is that we have to be able to
correctly remove only the functions inlined by the always-inline pass
when finalizing, which requires a bit of a hack. Still, much less of
a hack than the set of all non-always-inline functions was. While I was
touching this function, I switched a heavy-weight set to a vector with
sort+unique. The algorithm already had a two-phase insert and removal
pattern, we were just needlessly paying the uniquing cost on every
insert.

This probably speeds up some compiles by a small amount (-O0 compiles
with lots of always-inline, so potentially heavy libc++ users), but I've
not tried to measure it.

I believe there is no functional change here, but yell if you spot one.
None are intended.

Finally, the direction this is going in is to greatly simplify the
inline cost query interface so that we can replace its implementation
with a much more clever one. Along the way, all the APIs get simplified,
so it seems incrementally good.

llvm-svn: 152903
2012-03-16 06:10:13 +00:00
..
IPA LLVMBuild: Remove trailing newline, which irked me. 2011-12-12 19:48:00 +00:00
AliasAnalysis.cpp Move isKnownNonNull from private implementation detail of BasicAA to a public 2012-02-25 10:56:28 +00:00
AliasAnalysisCounter.cpp Persuade GCC that there is nothing worth warning about here (there isn't). 2012-02-05 14:20:11 +00:00
AliasAnalysisEvaluator.cpp Remove unnecessary default cases in switches that cover all enum values. 2012-01-10 16:47:17 +00:00
AliasDebugger.cpp
AliasSetTracker.cpp Have AliasSet::aliasesUnknownInst use pointer TBAA info when available 2012-02-10 15:52:39 +00:00
Analysis.cpp C API functions must be able to see their extern "C" definitions, or it will be impossible to call them from C. 2011-08-19 01:36:54 +00:00
BasicAliasAnalysis.cpp Duncan pointed out that if the alignment isn't explicitly specified, it defaults to the ABI alignment. Given that, make this code a bit more aggressive in such cases. 2012-02-27 23:16:46 +00:00
BlockFrequencyInfo.cpp Add some constantness to BranchProbabilityInfo and BlockFrequnencyInfo. 2011-12-20 20:03:10 +00:00
BranchProbabilityInfo.cpp Make the unreachable probability much much heavier. The previous 2011-12-22 09:26:37 +00:00
CaptureTracking.cpp Move includes to the .cpp file. 2012-01-17 22:16:31 +00:00
CFGPrinter.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
CMakeLists.txt Pull the implementation of the code metrics out of the inline cost 2012-03-16 05:51:52 +00:00
CodeMetrics.cpp Pull the implementation of the code metrics out of the inline cost 2012-03-16 05:51:52 +00:00
ConstantFolding.cpp Convert assert(0) to llvm_unreachable 2012-02-07 05:05:23 +00:00
DbgInfoPrinter.cpp Fix for DbgInfoPrinter.cpp:174:12: warning: ‘LineNo’ may be used uninitialized in this function. 2011-09-21 23:34:23 +00:00
DebugInfo.cpp Do the right thing on NULL uint64 fields. 2012-03-16 00:21:54 +00:00
DIBuilder.cpp Add support for runtime languages on our forward declarations. 2012-02-20 18:04:14 +00:00
DominanceFrontier.cpp Unweaken vtables as per http://llvm.org/docs/CodingStandards.html#ll_virtual_anch 2011-12-20 02:50:00 +00:00
DomPrinter.cpp remove the blank line from previous ci. 2012-02-04 03:18:47 +00:00
InlineCost.cpp Start removing the use of an ad-hoc 'never inline' set and instead 2012-03-16 06:10:13 +00:00
InstCount.cpp
InstructionSimplify.cpp Type sizes and fields offsets inside structs are unsigned. This is a highly 2012-03-15 20:14:42 +00:00
Interval.cpp
IntervalPartition.cpp
IVUsers.cpp LSR fix: Add isSimplifiedLoopNest to IVUsers analysis. 2012-03-16 03:16:56 +00:00
LazyValueInfo.cpp llvm::SwitchInst 2012-03-11 06:09:17 +00:00
LibCallAliasAnalysis.cpp
LibCallSemantics.cpp
Lint.cpp Fix a few more places where TargetData/TargetLibraryInfo is not being passed. 2011-12-02 01:26:24 +00:00
LLVMBuild.txt LLVMBuild: Introduce a common section which currently has a list of the 2011-12-12 22:45:54 +00:00
Loads.cpp enhance jump threading to preserve TBAA information when PRE'ing loads, 2012-03-13 18:07:41 +00:00
LoopDependenceAnalysis.cpp More dead code removal (using -Wunreachable-code) 2012-01-20 21:51:11 +00:00
LoopInfo.cpp Move Instruction::isSafeToSpeculativelyExecute out of VMCore and 2011-12-14 23:49:11 +00:00
LoopPass.cpp Reapply r138695. Fix PassManager stack depths. 2011-08-29 17:07:00 +00:00
Makefile
MemDepPrinter.cpp Fix a stupid typo in MemDepPrinter. 2011-12-14 02:54:39 +00:00
MemoryBuiltins.cpp Validate the return type when checking if a function is malloc. 2011-11-23 17:58:47 +00:00
MemoryDependenceAnalysis.cpp Don't call dominates on unreachable instructions. Should fix the dragonegg 2012-02-26 05:30:08 +00:00
ModuleDebugInfoPrinter.cpp
NoAliasAnalysis.cpp
PathNumbering.cpp [unwind removal] We no longer have 'unwind' instructions being generated, so 2012-02-06 21:16:41 +00:00
PathProfileInfo.cpp
PathProfileVerifier.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
PHITransAddr.cpp Uniformize the InstructionSimplify interface by ensuring that all routines 2012-03-13 11:42:19 +00:00
PostDominators.cpp
ProfileEstimatorPass.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
ProfileInfo.cpp
ProfileInfoLoader.cpp
ProfileInfoLoaderPass.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
ProfileVerifierPass.cpp Move code into anonymous namespaces. 2011-11-26 23:01:57 +00:00
README.txt
RegionInfo.cpp Remove extra semi-colons. 2012-02-22 17:25:00 +00:00
RegionPass.cpp Reapply r138695. Fix PassManager stack depths. 2011-08-29 17:07:00 +00:00
RegionPrinter.cpp
ScalarEvolution.cpp switch SCEV to use the new ConstantFoldLoadThroughGEPIndices function 2012-01-24 05:49:24 +00:00
ScalarEvolutionAliasAnalysis.cpp
ScalarEvolutionExpander.cpp Fix this assert. IP can point to an instruction with strange dominance 2012-02-27 02:13:03 +00:00
ScalarEvolutionNormalization.cpp More dead code removal (using -Wunreachable-code) 2012-01-20 21:51:11 +00:00
SparsePropagation.cpp Taken into account Duncan's comments for r149481 dated by 2nd Feb 2012: 2012-03-08 07:06:20 +00:00
Trace.cpp Remove all remaining uses of Value::getNameStr(). 2011-11-15 16:27:03 +00:00
TypeBasedAliasAnalysis.cpp
ValueTracking.cpp Factor out the analysis of addition and subtraction in ComputeMaskedBits. Reuse 2012-03-09 09:23:50 +00:00

Analysis Opportunities:

//===---------------------------------------------------------------------===//

In test/Transforms/LoopStrengthReduce/quadradic-exit-value.ll, the
ScalarEvolution expression for %r is this:

  {1,+,3,+,2}<loop>

Outside the loop, this could be evaluated simply as (%n * %n), however
ScalarEvolution currently evaluates it as

  (-2 + (2 * (trunc i65 (((zext i64 (-2 + %n) to i65) * (zext i64 (-1 + %n) to i65)) /u 2) to i64)) + (3 * %n))

In addition to being much more complicated, it involves i65 arithmetic,
which is very inefficient when expanded into code.

//===---------------------------------------------------------------------===//

In formatValue in test/CodeGen/X86/lsr-delayed-fold.ll,

ScalarEvolution is forming this expression:

((trunc i64 (-1 * %arg5) to i32) + (trunc i64 %arg5 to i32) + (-1 * (trunc i64 undef to i32)))

This could be folded to

(-1 * (trunc i64 undef to i32))

//===---------------------------------------------------------------------===//