Commit Graph

19199 Commits

Author SHA1 Message Date
Michael Ilseman
1b3ab9199f Add support for software expansion of 64-bit integer division instructions.
Patch by Dmitri Shtilman!



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195116 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-19 06:54:19 +00:00
Andrew Trick
0b843861c6 Fix patchpoint comments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195103 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-19 05:05:43 +00:00
Andrew Trick
8ddf988ef4 Add an abstraction to handle patchpoint operands.
Hard-coded operand indices were scattered throughout lowering stages
and layers. It was super bug prone.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195093 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-19 03:29:56 +00:00
Juergen Ributzka
354362524a [weak vtables] Remove a bunch of weak vtables
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file. The memory leaks in this version have been fixed. Thanks
Alexey for pointing them out.

Differential Revision: http://llvm-reviews.chandlerc.com/D2068

Reviewed by Andy

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195064 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-19 00:57:56 +00:00
David Blaikie
4adba52570 DebugInfo: Simplify a few more explicit constructions, underconstrained types, and make DIType(MDNode*) explicit like all the other DI* node ctors.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195055 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-18 23:33:32 +00:00
Alexander Kornienko
6919bec07f Recover gracefully when deserializing invalid YAML input.
Fixes http://llvm.org/PR16221, http://llvm.org/PR15927
Phabricator: http://llvm-reviews.chandlerc.com/D1236

Patch by Andrew Tulloch!


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195016 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-18 15:50:04 +00:00
Alexey Samsonov
f56f1dfecc Fix forgotten member initialization detected by MSan bootstrap bot
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195003 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-18 11:06:01 +00:00
Alexey Samsonov
b21ab43cfc Revert r194865 and r194874.
This change is incorrect. If you delete virtual destructor of both a base class
and a subclass, then the following code:
  Base *foo = new Child();
  delete foo;
will not cause the destructor for members of Child class. As a result, I observe
plently of memory leaks. Notable examples I investigated are:
ObjectBuffer and ObjectBufferStream, AttributeImpl and StringSAttributeImpl.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194997 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-18 09:31:53 +00:00
Hao Liu
97577757c6 Implement the newly added ACLE functions for ld1/st1 with 2/3/4 vectors.
The functions are like: vst1_s8_x2 ...


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194990 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-18 06:31:53 +00:00
Matt Arsenault
1572ba716b Fix spacing, forward declare order.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194985 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-18 02:51:33 +00:00
Manman Ren
6950be2851 Debug Info: fix typo in function name.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194975 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 19:35:03 +00:00
Manman Ren
2b31b8227f Debug Info Verifier: enable public functions of Finder to update the type map.
We used to depend on running processModule before the other public functions
such as processDeclare, processValue and processLocation. We are now relaxing
the constraint by adding a module argument to the three functions and
letting the three functions to initialize the type map. This will be used in
a follow-on patch that collects nodes reachable from a Function.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194973 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 18:42:37 +00:00
Hal Finkel
c8dc96be28 Add a loop rerolling flag to the PassManagerBuilder
This adds a boolean member variable to the PassManagerBuilder to control loop
rerolling (just like we have for unrolling and the various vectorization
options). This is necessary for control by the frontend. Loop rerolling remains
disabled by default at all optimization levels.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194966 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 16:02:50 +00:00
Yaron Keren
e5a694ab57 DebugLoc defines LineCol as 32 bit in comment but unsigned in code.
This patch modifies LineCol to be a uint32_t.

See http://llvm.org/bugs/show_bug.cgi?id=17957



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194957 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 09:47:39 +00:00
Michael Gottesman
e7a1e3ee82 [block-freq] Add BlockFrequency::scale that returns a remainder from the division and make the private scale in BlockFrequency more performant.
This change is the first in a series of changes improving LLVM's Block
Frequency propogation implementation to not lose probability mass in
branchy code when propogating block frequency information from a basic
block to its successors. This patch is a simple infrastructure
improvement that does not actually modify the block frequency
algorithm. The specific changes are:

1. Changes the division algorithm used when scaling block frequencies by
branch probabilities to a short division algorithm. This gives us the
remainder for free as well as provides a nice speed boost. When I
benched the old routine and the new routine on a Sandy Bridge iMac with
disabled turbo mode performing 8192 iterations on an array of length
32768, I saw ~600% increase in speed in mean/median performance.

2. Exposes a scale method that returns a remainder. This is important so
we can ensure that when we scale a block frequency by some branch
probability BP = N/D, the remainder from the division by D can be
retrieved and propagated to other children to ensure no probability mass
is lost (more to come on this).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194950 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 03:25:24 +00:00
Chandler Carruth
8417e85781 [PM] Completely remove support for explicit 'require' methods on the
AnalysisManager. All this method did was assert something and we have
a perfectly good way to trigger that assert from the query path.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194947 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 03:18:05 +00:00
Andrew Trick
bb756ca244 Added a size field to the stack map record to handle subregister spills.
Implementing this on bigendian platforms could get strange. I added a
target hook, getStackSlotRange, per Jakob's recommendation to make
this as explicit as possible.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194942 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-17 01:36:23 +00:00
Hal Finkel
bebe48dbfe Add a loop rerolling pass
This adds a loop rerolling pass: the opposite of (partial) loop unrolling. The
transformation aims to take loops like this:

for (int i = 0; i < 3200; i += 5) {
  a[i]     += alpha * b[i];
  a[i + 1] += alpha * b[i + 1];
  a[i + 2] += alpha * b[i + 2];
  a[i + 3] += alpha * b[i + 3];
  a[i + 4] += alpha * b[i + 4];
}

and turn them into this:

for (int i = 0; i < 3200; ++i) {
  a[i] += alpha * b[i];
}

and loops like this:

for (int i = 0; i < 500; ++i) {
  x[3*i] = foo(0);
  x[3*i+1] = foo(0);
  x[3*i+2] = foo(0);
}

and turn them into this:

for (int i = 0; i < 1500; ++i) {
  x[i] = foo(0);
}

There are two motivations for this transformation:

  1. Code-size reduction (especially relevant, obviously, when compiling for
code size).

  2. Providing greater choice to the loop vectorizer (and generic unroller) to
choose the unrolling factor (and a better ability to vectorize). The loop
vectorizer can take vector lengths and register pressure into account when
choosing an unrolling factor, for example, and a pre-unrolled loop limits that
choice. This is especially problematic if the manual unrolling was optimized
for a machine different from the current target.

The current implementation is limited to single basic-block loops only. The
rerolling recognition should work regardless of how the loop iterations are
intermixed within the loop body (subject to dependency and side-effect
constraints), but the significant restriction is that the order of the
instructions in each iteration must be identical. This seems sufficient to
capture all current use cases.

This pass is not currently enabled by default at any optimization level.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194939 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-16 23:59:05 +00:00
Benjamin Kramer
2905440bdd ScalarEvolution: Warn if the result of setFlags/clearFlags is unused.
This was a source of bugs in the past.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194929 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-16 16:25:47 +00:00
Benjamin Kramer
b69143c6a9 Annotate APInt methods where it's not clear whether they are in place with warn_unused_result.
Fix ScalarEvolution bugs uncovered by this.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194928 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-16 16:25:41 +00:00
Duncan P. N. Exon Smith
bd9f36f4db Fix filename in header comment
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194924 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-16 15:40:54 +00:00
Jim Grosbach
35de9946d5 X86: Encode the 'h' cpu subtype in the MachO header for x86.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194906 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-16 00:52:57 +00:00
Ana Pazos
a53bf06f7a Implemented aarch64 Neon scalar vmulx_lane intrinsics
Implemented aarch64 Neon scalar vfma_lane intrinsics
Implemented aarch64 Neon scalar vfms_lane intrinsics

Implemented legacy vmul_n_f64, vmul_lane_f64, vmul_laneq_f64
intrinsics (v1f64 parameter type) using Neon scalar instructions.

Implemented legacy vfma_lane_f64, vfms_lane_f64,
vfma_laneq_f64, vfms_laneq_f64 intrinsics (v1f64 parameter type)
using Neon scalar instructions.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194888 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 23:32:10 +00:00
Juergen Ributzka
5a364c5561 [weak vtables] Remove a bunch of weak vtables
This patch removes most of the trivial cases of weak vtables by pinning them to
a single object file.

Differential Revision: http://llvm-reviews.chandlerc.com/D2068

Reviewed by Andy

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194865 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 22:34:48 +00:00
Chad Rosier
5758c3c832 [AArch64] Fix the scalar NEON ACLE functions so that they return float/double
rather than the vector equivalent.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194853 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 21:28:10 +00:00
Rui Ueyama
8a631b2cbe Path: Recognize COFF import library file magic.
Summary: Make identify_magic to recognize COFF import file.

Reviewers: Bigcheese

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D2165

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194852 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 21:22:02 +00:00
Rui Ueyama
3a226015a0 Readobj: If NumbersOfSections is 0xffff, it's an COFF import library.
0xffff does not mean that there are 65535 sections in a COFF file but
indicates that it's a COFF import library. This patch fixes SEGV error
when an import library file is passed to llvm-readobj.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194844 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 20:23:25 +00:00
Bob Wilson
cc7052343e Avoid illegal integer promotion in fastisel
Stop folding constant adds into GEP when the type size doesn't match.
Otherwise, the adds' operands are effectively being promoted, changing the
conditions of an overflow.  Results are different when:

    sext(a) + sext(b) != sext(a + b)

Problem originally found on x86-64, but also fixed issues with ARM and PPC,
which used similar code.

<rdar://problem/15292280>

Patch by Duncan Exon Smith!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194840 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 19:09:27 +00:00
Cameron McInally
28e12e9f02 Add AVX512 unmasked FMA intrinsics and support.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194824 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 17:01:14 +00:00
Daniel Sanders
ea28aafa83 Fix illegal DAG produced by SelectionDAG::getConstant() for v2i64 type
Summary:
When getConstant() is called for an expanded vector type, it is split into
multiple scalar constants which are then combined using appropriate build_vector
and bitcast operations.

In addition to the usual big/little endian differences, the case where the
element-order of the vector does not have the same endianness as the elements
themselves is also accounted for.  For example, for v4i32 on big-endian MIPS,
the byte-order of the vector is <3210,7654,BA98,FEDC>. For little-endian, it is
<0123,4567,89AB,CDEF>.
Handling this case turns out to be a nop since getConstant() returns a splatted
vector (so reversing the element order doesn't change the value)

This fixes a number of cases in MIPS MSA where calling getConstant() during
operation legalization introduces illegal types (e.g. to legalize v2i64 UNDEF
into a v2i64 BUILD_VECTOR of illegal i64 zeros). It should also handle bigger
differences between illegal and legal types such as legalizing v2i64 into v8i16.

lowerMSASplatImm() in the MIPS backend no longer needs to avoid calling
getConstant() so this function has been updated in the same patch.

For the sake of transparency, the steps I've taken since the review are:
* Added 'virtual' to isVectorEltOrderLittleEndian() as requested. This revealed
  that the MIPS tests were falsely passing because a polymorphic function was
  not actually polymorphic in the reviewed patch.
* Fixed the tests that were now failing. This involved deleting the code to
  handle the MIPS MSA element-order (which was previously doing an byte-order
  swap instead of an element-order swap). This left
  isVectorEltOrderLittleEndian() unused and it was deleted.
* Fixed build failures caused by rebasing beyond r194467-r194472. These build
  failures involved the bset, bneg, and bclr instructions added in these commits
  using lowerMSASplatImm() in a way that was no longer valid after this patch.
  Some of these were fixed by calling SelectionDAG::getConstant() instead,
  others were fixed by a new function getBuildVectorSplat() that provided the
  removed functionality of lowerMSASplatImm() in a more sensible way.

Reviewers: bkramer

Reviewed By: bkramer

CC: llvm-commits

Differential Revision: http://llvm-reviews.chandlerc.com/D1973

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194811 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 12:56:49 +00:00
Matt Arsenault
509a492442 Add target hook to prevent folding some bitcasted loads.
This is to avoid this transformation in some cases:
fold (conv (load x)) -> (load (conv*)x)

On architectures that don't natively support some vector
loads efficiently casting the load to a smaller vector of
larger types and loading is more efficient.

Patch by Micah Villmow.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194783 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 04:42:23 +00:00
Peter Zotov
fa74752298 [llvm-c] Add missing const qualifiers to LLVMCreateTargetMachine
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194770 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 02:51:12 +00:00
Peter Zotov
5ea0c20ce7 [llvm-c] Simplify signature of LLVMGetTargetFromName
LLVMGetTargetFromName was not yet present in an LLVM release,
so this does not break compatibility.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194769 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 02:51:01 +00:00
Matt Arsenault
59d3ae6cdc Add addrspacecast instruction.
Patch by Michele Scandale!

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194760 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 01:34:59 +00:00
Rui Ueyama
2b7fef0ad4 Include raw_ostream.h.
Including only Debug.h did not cause a compilation error, but you couldn't
do anything (like writing something with <<) to raw_ostreams returned by
llvm::dbgs() or llvm::errs() without including raw_ostream.h. So including
it from Debug.h should make sense.

Differential Revision: http://llvm-reviews.chandlerc.com/D2183

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194759 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-15 01:25:34 +00:00
Chandler Carruth
4701c4702e Fix the header comment of the new pass manager stuff to not claim to be
the legacy stuff. =]

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194689 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 10:55:14 +00:00
Kevin Qin
0710afb9af [AArch64 neon] support poly64 and relevant intrinsic functions.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194659 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 03:27:58 +00:00
Kevin Qin
a08063a000 Implement aarch64 neon instruction class SIMD misc.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194656 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 02:44:13 +00:00
Nick Kledzik
04fca67d6f Add dyn_cast<> support to YAML I/O's IO class
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194655 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 02:38:07 +00:00
Michael Gottesman
e2058ff5bd Added BlockFrequencyInfo::view for displaying the block frequency propagation graph via graphviz.
This is useful for debugging issues in the BlockFrequency implementation since
one can easily visualize where probability mass and other errors occur in the
propagation.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194654 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 02:27:46 +00:00
Jiangning Liu
082ac99cc8 Implement AArch64 NEON instruction set AdvSIMD (table).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194648 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 01:57:32 +00:00
Nick Kledzik
4e7c22a90b Add simple support for tags in YAML I/O
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194644 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 00:59:59 +00:00
Yuchen Wu
4bd0224887 llvm-cov: Slightly improved error checking.
- readInt() should check all 4 bytes can be read, not just 1.
- In the event of false data in the gcno file, it was possible to index
  into a non-existent index of SmallVector, causing assertion error.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194639 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 00:38:41 +00:00
Yuchen Wu
131a764e0e llvm-cov: Removed StringMap holding GCOVLines.
According to the hazy gcov documentation, it appeared to be technically
possible for lines within a block to belong to different source files.
However, upon further investigation, gcov does not actually support
multiple source files for a single block.

This change removes a level of separation between blocks and lines by
replacing the StringMap of GCOVLines with a SmallVector of ints
representing line numbers. This also means that the GCOVLines class is
no longer needed.

This paves the way for supporting the "-a" option, which will output
block information.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194637 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 00:32:00 +00:00
Yuchen Wu
dbb51ff01f llvm-cov: Replaced asserts with proper error handling.
Unified the interface for read functions. They all return a boolean
indicating if the read from file succeeded. Functions that previously
returned the read value now store it into a variable that is passed in
by reference instead. Callers will need to check the return value to
detect if an error occurred.

Also added a new test which ensures that no assertions occur when file
contains invalid data. llvm-cov should return with error code 1 upon
failure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194635 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-14 00:07:15 +00:00
Chad Rosier
11966d7c98 [AArch64] Add support for legacy AArch32 NEON scalar shift by immediate
instructions.  This patch does not include the shift right and accumulate
instructions.  A number of non-overloaded intrinsics have been remove in favor
of their overloaded counterparts.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194598 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-13 20:05:37 +00:00
Benjamin Kramer
43a0f3959e Make sure LLVMLoadLibraryPermanently gets an extern "C" symbol.
Otherwise it's impossible to use it. Also don't include C++ headers in
a C header.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194581 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-13 15:35:13 +00:00
Rafael Espindola
de9a1a2055 Remove AllowQuotesInName and friends from MCAsmInfo.
Accepting quotes is a property of an assembler, not of an object file. For
example, ELF can support any names for sections and symbols, but the gnu
assembler only accepts quotes in some contexts and llvm-mc in a few more.

LLVM should not produce different symbols based on a guess about which assembler
will be reading the code it is printing.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194575 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-13 14:01:59 +00:00
Diego Novillo
563b29f8db SampleProfileLoader pass. Initial setup.
This adds a new scalar pass that reads a file with samples generated
by 'perf' during runtime. The samples read from the profile are
incorporated and emmited as IR metadata reflecting that profile.

The profile file is assumed to have been generated by an external
profile source. The profile information is converted into IR metadata,
which is later used by the analysis routines to estimate block
frequencies, edge weights and other related data.

External profile information files have no fixed format, each profiler
is free to define its own. This includes both the on-disk representation
of the profile and the kind of profile information stored in the file.
A common kind of profile is based on sampling (e.g., perf), which
essentially counts how many times each line of the program has been
executed during the run.

The SampleProfileLoader pass is organized as a scalar transformation.
On startup, it reads the file given in -sample-profile-file to
determine what kind of profile it contains.  This file is assumed to
contain profile information for the whole application. The profile
data in the file is read and incorporated into the internal state of
the corresponding profiler.

To facilitate testing, I've organized the profilers to support two file
formats: text and native. The native format is whatever on-disk
representation the profiler wants to support, I think this will mostly
be bitcode files, but it could be anything the profiler wants to
support. To do this, every profiler must implement the
SampleProfile::loadNative() function.

The text format is mostly meant for debugging. Records are separated by
newlines, but each profiler is free to interpret records as it sees fit.
Profilers must implement the SampleProfile::loadText() function.

Finally, the pass will call SampleProfile::emitAnnotations() for each
function in the current translation unit. This function needs to
translate the loaded profile into IR metadata, which the analyzer will
later be able to use.

This patch implements the first steps towards the above design. I've
implemented a sample-based flat profiler. The format of the profile is
fairly simplistic. Each sampled function contains a list of relative
line locations (from the start of the function) together with a count
representing how many samples were collected at that line during
execution. I generate this profile using perf and a separate converter
tool.

Currently, I have only implemented a text format for these profiles. I
am interested in initial feedback to the whole approach before I send
the other parts of the implementation for review.

This patch implements:

- The SampleProfileLoader pass.
- The base ExternalProfile class with the core interface.
- A SampleProfile sub-class using the above interface. The profiler
  generates branch weight metadata on every branch instructions that
  matches the profiles.
- A text loader class to assist the implementation of
  SampleProfile::loadText().
- Basic unit tests for the pass.

Additionally, the patch uses profile information to compute branch
weights based on instruction samples.

This patch converts instruction samples into branch weights. It
does a fairly simplistic conversion:

Given a multi-way branch instruction, it calculates the weight of
each branch based on the maximum sample count gathered from each
target basic block.

Note that this assignment of branch weights is somewhat lossy and can be
misleading. If a basic block has more than one incoming branch, all the
incoming branches will get the same weight. In reality, it may be that
only one of them is the most heavily taken branch.

I will adjust this assignment in subsequent patches.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194566 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-13 12:22:21 +00:00
Chandler Carruth
429af0e0a7 Add another (perhaps better) video for Sean's talk. (Thanks Marshall!)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194549 91177308-0d34-0410-b5e6-96231b3b80d8
2013-11-13 02:49:38 +00:00