Commit Graph

20426 Commits

Author SHA1 Message Date
Craig Topper
57d7597572 Remove an unused version of getMemIntrinsicNode and getNode. Additionally, these were calling makeVTList with the pointers passed in which would were unlikely to belong to SelectionDAG and likely would have just been stack pointers.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207326 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 18:35:13 +00:00
Benjamin Kramer
aab6231cd9 DAGCombiner: Turn divs of vector splats into vectorized multiplications.
Otherwise the legalizer would just scalarize everything. Support for
mulhi in the targets isn't that great yet so on most targets we get
exactly the same scalarized output. Add a test for x86 vector udiv.

I had to disable the mulhi nodes on ARM because there aren't any patterns
for it. As far as I know ARM has instructions for getting the high part of
a multiply so this should be fixed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207315 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 12:06:28 +00:00
Michael Zolotukhin
abd7ca0706 Revert r206749 till a final decision about the intrinsics is made.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207313 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 09:56:41 +00:00
Chandler Carruth
9a1fab37c7 [LCG] Rather than removing nodes from the SCC entry set when we process
them, just skip over any DFS-numbered nodes when finding the next root
of a DFS. This allows the entry set to just be a vector as we populate
it from a uniqued source. It also removes the possibility for a linear
scan of the entry set to actually do the removal which can make things
go quadratic if we get unlucky.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207312 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 09:45:55 +00:00
Chandler Carruth
8495669112 [LCG] Hoist the main DFS loop out of the edge removal function. This
makes working through the worklist much cleaner, and makes it possible
to avoid the 'bool-to-continue-the-outer-loop' hack. Not a huge
difference, but I think this is approaching as polished as I can make
it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207310 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 09:06:53 +00:00
Chandler Carruth
dec9a2ca23 [LCG] In the incremental SCC re-formation, lift the node currently being
processed in the DFS out of the stack completely. Keep it exclusively in
a variable. Re-shuffle some code structure to make this easier. This can
have a very dramatic effect in some cases because call graphs tend to
look like a high fan-out spanning tree. As a consequence, there are
a large number of leaf nodes in the graph, and this technique causes
leaf nodes to never even go into the stack. While this only reduces the
max depth by 1, it may cause the total number of round trips through the
stack to drop by a lot.

Now, most of this isn't really relevant for the incremental version. =]
But I wanted to prototype it first here as this variant is in ways more
complex. As long as I can get the code factored well here, I'll next
make the primary walk look the same. There are several refactorings this
exposes I think.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207306 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 03:36:42 +00:00
Chandler Carruth
64e1be4bf1 [LCG] Refactor the duplicated code I added in my last commit here into
a helper function. Also factor the other two places where we did the
same thing into the helper function. =] Much cleaner this way. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207300 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-26 01:03:46 +00:00
Duncan P. N. Exon Smith
cee7abfb2c Revert "blockfreq: Approximate irreducible control flow"
This reverts commit r207286.  It causes an ICE on the
cmake-llvm-x86_64-linux buildbot [1]:

    llvm/lib/Analysis/BlockFrequencyInfo.cpp: In lambda function:
    llvm/lib/Analysis/BlockFrequencyInfo.cpp:182:1: internal compiler error: in get_expr_operands, at tree-ssa-operands.c:1035

[1]: http://bb.pgr.jp/builders/cmake-llvm-x86_64-linux/builds/12093/steps/build_llvm/logs/stdio

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207287 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 23:16:58 +00:00
Duncan P. N. Exon Smith
d905bba691 blockfreq: Approximate irreducible control flow
Previously, irreducible backedges were ignored.  With this commit,
irreducible SCCs are discovered on the fly, and modelled as loops with
multiple headers.

This approximation specifies the headers of irreducible sub-SCCs as its
entry blocks and all nodes that are targets of a backedge within it
(excluding backedges within true sub-loops).  Block frequency
calculations act as if we insert a new block that intercepts all the
edges to the headers.  All backedges and entries to the irreducible SCC
point to this imaginary block.  This imaginary block has an edge (with
even probability) to each header block.

The result is now reasonable enough that I've added a number of
testcases for irreducible control flow.  I've outlined in
`BlockFrequencyInfoImpl.h` ways to improve the approximation.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207286 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 23:08:57 +00:00
Tom Roeder
817f5e2fa1 Add an -mattr option to the gold plugin to support subtarget features in LTO
This adds support for an -mattr option to the gold plugin and to llvm-lto. This
allows the caller to specify details of the subtarget architecture, like +aes,
or +ssse3 on x86.  Note that this requires a change to the include/llvm-c/lto.h
interface: it adds a function lto_codegen_set_attr and it increments the
version of the interface.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207279 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 21:46:51 +00:00
Duncan P. N. Exon Smith
d9dc95709e SCC: Use the reference typedef
Actually use the `reference` typedef, and remove the private
redefinition of `pointer` since it has no users.

Using `reference` exposes a problem with r207257, which specified the
wrong `value_type` to `iterator_facade_base` (fixed that too).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207270 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 20:52:08 +00:00
Adrian Prantl
988b78a846 This reapplies r207235 with an additional bugfixes caught by the msan
buildbot - do not insert debug intrinsics before phi nodes.

Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207269 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 20:49:25 +00:00
David Blaikie
31494cb6c4 MCAssembler: Simplify implementation of const variants of getSymbolData by calling one implementation from the other.
Code review feedback by Rafael Espindola on r207124.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207266 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 20:19:11 +00:00
Duncan P. N. Exon Smith
2d18167483 blockfreq: Further shift logic to LoopData
Move a lot of the loop-related logic that was sprinkled around the code
into `LoopData`.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207258 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:47:04 +00:00
Duncan P. N. Exon Smith
eae0809a60 SCC: Provide operator->() through iterator_facade_base
Use the fancy new `iterator_facade_base` to add
`scc_iterator::operator->()`.  Remove other definitions where
`iterator_facade_base` does the right thing.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207257 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:43:41 +00:00
Duncan P. N. Exon Smith
d86dbccfef SCC: Remove non-const operator*()
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207254 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:26:45 +00:00
Duncan P. N. Exon Smith
5a6277a230 SCC: Doxygen-ize comments, NFC
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207251 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:18:46 +00:00
Adrian Prantl
25c74de500 Revert "This reapplies r207130 with an additional testcase+and a missing check for"
This reverts commit 207235 to investigate msan buildbot breakage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207250 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:18:09 +00:00
Duncan P. N. Exon Smith
ad56833808 SCC: Un-inline long functions
These are long functions that really shouldn't be inlined.  Otherwise,
no functionality change.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207249 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:15:50 +00:00
Duncan P. N. Exon Smith
f40905c318 SCC: Remove redundant inline keywords, NFC
Functions declared in line in a class are inlined by default.  There's
no reason for the `inline` keyword.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207248 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 18:10:23 +00:00
Saleem Abdulrasool
25bc383612 ARM: remove @llvm.arm.sevl
This intrinsic is no longer needed with the new @llvm.arm.hint(i32) intrinsic
which provides a generic, extensible manner for adding hint instructions.  This
functionality can now be represented as @llvm.arm.hint(i32 5).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207246 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 17:51:25 +00:00
Saleem Abdulrasool
04f826c062 ARM: provide a new generic hint intrinsic
Introduce the llvm.arm.hint(i32) intrinsic that can be used to inject hints into
the instruction stream. This is particularly useful for generating IR from a
compiler where the user may inject an intrinsic (e.g. __yield). These are then
pattern substituted into the correct instruction which already existed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207242 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 17:24:24 +00:00
Adrian Prantl
7e96d88347 This reapplies r207130 with an additional testcase+and a missing check for
AllocaInst that was missing in one location.
Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207235 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 17:01:00 +00:00
Craig Topper
8d7221ccf5 [C++] Use 'nullptr'. Transforms edition.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207196 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 05:29:35 +00:00
Duncan P. N. Exon Smith
39087bfbf0 blockfreq: Only one mass distribution per node
Remove the concepts of "forward" and "general" mass distributions, which
was wrong.  The split might have made sense in an early version of the
algorithm, but it's definitely wrong now.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207195 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:43 +00:00
Duncan P. N. Exon Smith
16df231a82 blockfreq: Document high-level functions
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207191 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:32 +00:00
Duncan P. N. Exon Smith
7cb80111c3 blockfreq: Remove dead code
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207190 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:30 +00:00
Duncan P. N. Exon Smith
3475765998 blockfreq: Separate unwrapLoops() from finalizeMetrics()
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207185 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:17 +00:00
Duncan P. N. Exon Smith
e839ab26ba blockfreq: LoopData::MemberList => NodeList
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207184 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:15 +00:00
Duncan P. N. Exon Smith
7ed8c05157 blockfreq: Expose getPackagedNode()
Make `getPackagedNode()` a member function of
`BlockFrequencyInfoImplBase` so that it's available for templated code.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207183 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:12 +00:00
Duncan P. N. Exon Smith
3df8534be1 blockfreq: Store the header with the members
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207182 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:09 +00:00
Duncan P. N. Exon Smith
7e26181f6b blockfreq: Encapsulate LoopData::Header
<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207181 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:06 +00:00
Duncan P. N. Exon Smith
625063d495 blockfreq: Embed Loop hierarchy in LoopData
Continue refactoring to make `LoopData` first-class.  Here I'm making
the `LoopData` hierarchy explicit, instead of bouncing back and forth
with `WorkingData`.  This simplifies the logic and better matches the
`LoopInfo` design.  (Eventually, `LoopInfo` should be restructured so
that it supports this pass, and `LoopData` can be removed.)

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207180 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:03 +00:00
Duncan P. N. Exon Smith
336238cebe blockfreq: Use LoopData directly
Instead of passing around loop headers, pass around `LoopData` directly.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207179 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:38:01 +00:00
Duncan P. N. Exon Smith
1e3d420da5 blockfreq: Stop using range-based for to traverse Loops
A follow-up commit will need the actual iterators.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207178 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:37:58 +00:00
Duncan P. N. Exon Smith
6f1f9f4c7f blockfreq: Use a std::list for Loops
As pointed out by David Blaikie in code review, a `std::list<T>` is
simpler than a `std::vector<std::unique_ptr<T>>`.  Another option is a
`std::deque<T>` (which allocates in chunks), but I'd like to leave open
the option of inserting in the middle of the sequence for handling
irreducible control flow on the fly.

<rdar://problem/14292693>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207177 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 04:30:06 +00:00
Karthik Bhat
ac16f0e024 Allow vectorization of bit intrinsics in BB Vectorizer.
This patch adds support for vectorization of  bit intrinsics such as bswap,ctpop,ctlz,cttz.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207174 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 03:33:48 +00:00
Adrian Prantl
680311d2d2 Revert "This reapplies r207130 with an additional testcase+and a missing check for"
Typo in testcase.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207166 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 00:42:50 +00:00
Adrian Prantl
50e7ba14ca This reapplies r207130 with an additional testcase+and a missing check for
AllocaInst that was missing in one location.
Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine.ll testcase and included source

rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207165 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 00:38:40 +00:00
Adrian Prantl
ab6ab3c333 Revert "Debug info for optimized code: Support variables that are on the stack and"
This reverts commit 207130 for buildbot breakage.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207162 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-25 00:04:49 +00:00
Richard Smith
e434cc2a4d Add missing include, found by modules build.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207158 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 23:29:25 +00:00
Richard Smith
12da0f2bcd Function defined in a header should be inline. Found by modules build.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207157 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 23:14:32 +00:00
Chandler Carruth
01f21349f2 [ADT] Generalize pointee_iterator to smart pointers by using decltype.
Based on review feedback from Dave on the original patch.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207146 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 21:10:35 +00:00
Reid Kleckner
1ce40b302d Remove dead inline function that doesn't compile
MSVC doesn't diagnose this, interestingly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207144 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 20:19:22 +00:00
Reid Kleckner
710c1a449d Add 'musttail' marker to call instructions
This is similar to the 'tail' marker, except that it guarantees that
tail call optimization will occur.  It also comes with convervative IR
verification rules that ensure that tail call optimization is possible.

Reviewers: nicholas

Differential Revision: http://llvm-reviews.chandlerc.com/D3240

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207143 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 20:14:34 +00:00
Richard Smith
778aacb5a3 [modules] "Specialize" a function by actually specializing a function template
rather than by adding an overload and hoping that it's declared before the code
that calls it. (In a modules build, it isn't.)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207133 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 18:27:29 +00:00
Adrian Prantl
f28f471f16 Debug info for optimized code: Support variables that are on the stack and
described by DBG_VALUEs during their lifetime.

Previously, when a variable was at a FrameIndex for any part of its
lifetime, this would shadow all other DBG_VALUEs and only a single
fbreg location would be emitted, which in fact is only valid for a small
range and not the entire lexical scope of the variable. The included
dbg-value-const-byref testcase demonstrates this.

This patch fixes this by
Local
- emitting dbg.value intrinsics for allocas that are passed by reference
- dropping all dbg.declares (they are now fully lowered to dbg.values)
SelectionDAG
- renamed constructors for SDDbgValue for better readability.
- fix UserValue::match() to handle indirect values correctly
- not inserting an MMI table entries for dbg.values that describe allocas.
- lowering dbg.values that describe allocas into *indirect* DBG_VALUEs.
CodeGenPrepare
- leaving dbg.values for an alloca were they are (see comment)
Other
- regenerated/updated instcombine-intrinsics testcase and included source


rdar://problem/16679879
http://reviews.llvm.org/D3374

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207130 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 17:41:45 +00:00
Andrea Di Biagio
35f9e1aa49 [X86] Add support for Read Time Stamp Counter x86 builtin intrinsics.
This patch:
- Adds two new X86 builtin intrinsics ('int_x86_rdtsc' and
   'int_x86_rdtscp') as GCCBuiltin intrinsics;
- Teaches the backend how to lower the two new builtins;
- Introduces a common function to lower READCYCLECOUNTER dag nodes
  and the two new rdtsc/rdtscp intrinsics;
- Improves (and extends) the existing x86 test 'rdtsc.ll'; now test 'rdtsc.ll'
  correctly verifies that both READCYCLECOUNTER and the two new intrinsics
  work fine for both 64bit and 32bit Subtargets.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207127 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 17:18:27 +00:00
David Blaikie
45966fa1f1 Spread some const around for non-mutating uses of MCSymbolData.
I discovered this const-hole while attempting to coalesnce the Symbol
and SymbolMap data structures. There's some pending issues with that,
but I figured this change was easy to flush early.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207124 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 16:59:40 +00:00
Chandler Carruth
befdb1a642 [LCG] Incorporate the core trick of improvements on the naive Tarjan's
algorithm here: http://dl.acm.org/citation.cfm?id=177301.

The idea of isolating the roots has even more relevance when using the
stack not just to implement the DFS but also to implement the recursive
step. Because we use it for the recursive step, to isolate the roots we
need to maintain two stacks: one for our recursive DFS walk, and another
of the nodes that have been walked. The nice thing is that the latter
will be half the size. It also fixes a complete hack where we scanned
backwards over the stack to find the next potential-root to continue
processing. Now that is always the top of the DFS stack.

While this is a really nice improvement already (IMO) it further opens
the door for two important simplifications:

1) De-duplicating some of the code across the two different walks. I've
   actually made the duplication a bit worse in some senses with this
   patch because the two are starting to converge.
2) Dramatically simplifying the loop structures of both walks.

I wanted to do those separately as they'll be essentially *just* CFG
restructuring. This patch on the other hand actually uses different
datastructures to implement the algorithm itself.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207098 91177308-0d34-0410-b5e6-96231b3b80d8
2014-04-24 11:05:20 +00:00