This seems to cause a miscompile when building clang, which causes a
bootstrapped clang to fail or crash in several of its tests.

See:
  http://lab.llvm.org:8013/builders/clang-x86_64-darwin11-RA/builds/1184
  http://bb.pgr.jp/builders/clang-3stage-x86_64-linux/builds/7813

This reverts commit r219282.

llvm-svn: 219317

Differential Revision: http://reviews.llvm.org/D5649
 

llvm-svn: 219286

A linkonce_odr member of a COMDAT shouldn't be dropped if we need to
keep the entire COMDAT group.

This fixes PR21191.

llvm-svn: 219283

The icmp-select-icmp optimization targets select-icmp.eq
only. This is now ensured by testing the branch predicate
explictly. This commit also includes the test case for pr21199.

llvm-svn: 219282

This seems to have caused PR21199.

llvm-svn: 219264

DebugInfo+DFSan: Ensure that debug info references to llvm::Functions remain pointing to the underlying function when wrappers are created

This is somewhat the inverse of how similar bugs in DAE and ArgPromo
manifested and were addressed. In those passes, individual call sites
were visited explicitly, and then the old function was deleted. This
left the debug info with a null llvm::Function* that needed to be
updated to point to the new function.

In the case of DFSan, it RAUWs the old function with the wrapper, which
includes debug info. So now the debug info refers to the wrapper, which
doesn't actually have any instructions with debug info in it, so it is
ignored entirely - resulting in a DW_TAG_subprogram with no high/low pc,
etc. Instead, fix up the debug info to refer to the original function
after the RAUW messed it up.

Reviewed/discussed with Peter Collingbourne on the llvm-dev mailing
list.

llvm-svn: 219249

`LoopUnrollPass` says that it preserves `LoopInfo` -- make it so.  In
particular, tell `LoopInfo` about copies of inner loops when unrolling
the outer loop.

Conservatively, also tell `ScalarEvolution` to forget about the original
versions of these loops, since their inputs may have changed.

Fixes PR20987.

llvm-svn: 219241

A follow-up commit will add use to a tight loop.  We might as well just
find it once anyway.

llvm-svn: 219239

This optimization tries to convert switch instructions that are used to select a value with only 2 unique cases + default block
to a select or a couple of selects (depending if the default block is reachable or not).

The typical case this optimization wants to be able to optimize is this one:

Example:
switch (a) {
  case 10:                %0 = icmp eq i32 %a, 10
    return 10;            %1 = select i1 %0, i32 10, i32 4
  case 20:        ---->   %2 = icmp eq i32 %a, 20
    return 2;             %3 = select i1 %2, i32 2, i32 %1
  default:
    return 4;
}

It also sets the base for further optimizations that are planned and being reviewed.

llvm-svn: 219223

DebugInfo+DeadArgElimination: Ensure llvm::Function*s from debug info are updated even when DAE removes both varargs and non-varargs arguments on the same function.

After some stellar (& inspired) help from Reid Kleckner providing a test
case for some rather unstable undefined behavior showing up as
assertions produced by r214761, I was able to fix this issue in DAE
involving the application of both varargs removal, followed by normal
argument removal.

Indeed I introduced this same bug into ArgumentPromotion (r212128) by
copying the code from DAE, and when I fixed the bug in ArgPromo
(r213805) and commented in that patch that I didn't need to address the
same issue in DAE because it was a single pass. Turns out it's two pass,
one for the varargs and one for the normal arguments, so the same fix is
needed (at least during varargs removal). So here it is.

(the observable/net effect of this bug, even when it didn't result in
assertion failure, is that debug info would describe the DAE'd function
in the abstract, but wouldn't provide high/low_pc, variable locations,
line table, etc (it would appear as though the function had been
entirely optimized away), see the original PR14016 for details of the
general problem)

I'm not recommitting the assertion just yet, as there's been another
regression of it since I last tried. It might just be a few test cases
weren't adequately updated after Adrian or Duncan's recent schema
changes.

llvm-svn: 219210

Differential Revision: http://reviews.llvm.org/D5644

llvm-svn: 219203

NFC.

Differential Revision: http://reviews.llvm.org/D5645

llvm-svn: 219202

Patch by Sonam Kumari!

Differential Revision: http://reviews.llvm.org/D5643

llvm-svn: 219198

If we require a single member of a comdat, require all of the other
members as well.

This fixes PR20981.

llvm-svn: 219191

Takes care of the assert that caused build fails.
Rather than asserting the code checks now that the definition
and use are in the same block, and does not attempt
to optimize when that is not the case.

llvm-svn: 219175

llvm-svn: 219167

Add new basic blocks to `LoopInfo` earlier.  No functionality change
intended (simplifies upcoming bugfix patch).

llvm-svn: 219150

llvm-svn: 219149

Particularly, it addresses cases where Reassociate breaks Subtracts but then fails to optimize combinations like I1 + -I2 where I1 and I2 have the same rank and are identical.

Patch by Dmitri Shtilman.

llvm-svn: 219092

Joerg suggested on IRC that I look at generalizing the logic from r219067 to
handle more general redundancies (like removing an assume(x > 3) dominated by
an assume(x > 5)). The way to do this would be to ask ValueTracking to
determine the value of the i1 argument. It turns out that ValueTracking is not
very good at this right now (although it does get the trivial redundancy case)
because it does not understand ICmps. Nevertheless, the resulting code in
InstCombine is simpler than r219067, so we might as well do it now.

llvm-svn: 219070

For any @llvm.assume intrinsic, if there is another which dominates it and uses
the same condition, then it is redundant and can be removed. While this does
not alter the semantics of the @llvm.assume intrinsics, it makes subsequent
handling more efficient (and the resulting IR easier to read).

llvm-svn: 219067

NFC.

llvm-svn: 219061

This reverts commit r218918, effectively reapplying r218914 after fixing
an Ocaml bindings test and an Asan crash.  The root cause of the latter
was a tightened-up check in `DILexicalBlock::Verify()`, so I'll file a
PR to investigate who requires the loose check (and why).

Original commit message follows.

--

This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString.  Integers are stringified and
a `\0` character is used as a separator.

Part of PR17891.

Note: I've attached my testcases upgrade scripts to the PR.  If I've
just broken your out-of-tree testcases, they might help.

llvm-svn: 219010

llvm-svn: 218999

This reverts commit r218914 while I investigate some bots.

llvm-svn: 218918

This patch addresses the first stage of PR17891 by folding constant
arguments together into a single MDString.  Integers are stringified and
a `\0` character is used as a separator.

Part of PR17891.

Note: I've attached my testcases upgrade scripts to the PR.  If I've
just broken your out-of-tree testcases, they might help.

llvm-svn: 218914

When unsafe-fp-math is enabled, we can turn sqrt(X) * sqrt(X) into X.

This can happen in the real world when calculating x ** 3/2. This occurs
in test-suite/SingleSource/Benchmarks/BenchmarkGame/n-body.c.

Differential Revision: http://reviews.llvm.org/D5584

llvm-svn: 218906

llvm-svn: 218876

My commit rL216160 introduced a bug PR21014: IndVars widens code 'for (i = ; i < ...; i++) arr[ CONST - i]' into 'for (i = ; i < ...; i++) arr[ i - CONST]'
thus inverting index expression. This patch fixes it. 
Thanks to Jörg Sonnenberger for pointing.

Differential Revision: http://reviews.llvm.org/D5576

llvm-svn: 218867

`DIExpression`'s elements are 64-bit integers that are stored as
`ConstantInt`.  The accessors already encapsulate the storage.  This
commit updates the `DIBuilder` API to also encapsulate that.

llvm-svn: 218797

argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

Note: I accidentally committed a bogus older version of this patch previously.
llvm-svn: 218787

"Move the complex address expression out of DIVariable and into an extra"

llvm-svn: 218782

argument of the llvm.dbg.declare/llvm.dbg.value intrinsics.

Previously, DIVariable was a variable-length field that has an optional
reference to a Metadata array consisting of a variable number of
complex address expressions. In the case of OpPiece expressions this is
wasting a lot of storage in IR, because when an aggregate type is, e.g.,
SROA'd into all of its n individual members, the IR will contain n copies
of the DIVariable, all alike, only differing in the complex address
reference at the end.

By making the complex address into an extra argument of the
dbg.value/dbg.declare intrinsics, all of the pieces can reference the
same variable and the complex address expressions can be uniqued across
the CU, too.
Down the road, this will allow us to move other flags, such as
"indirection" out of the DIVariable, too.

The new intrinsics look like this:
declare void @llvm.dbg.declare(metadata %storage, metadata %var, metadata %expr)
declare void @llvm.dbg.value(metadata %storage, i64 %offset, metadata %var, metadata %expr)

This patch adds a new LLVM-local tag to DIExpressions, so we can detect
and pretty-print DIExpression metadata nodes.

What this patch doesn't do:

This patch does not touch the "Indirect" field in DIVariable; but moving
that into the expression would be a natural next step.

http://reviews.llvm.org/D4919
rdar://problem/17994491

Thanks to dblaikie and dexonsmith for reviewing this patch!

llvm-svn: 218778

llvm-svn: 218775

Failing bootstrap on Linux (arm, x86).

http://lab.llvm.org:8011/builders/sanitizer-x86_64-linux/builds/13139/steps/bootstrap%20clang/logs/stdio
http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15-selfhost/builds/470
http://lab.llvm.org:8011/builders/clang-native-arm-lnt/builds/8518

llvm-svn: 218752

The icmp-select-icmp optimization made the implicit assumption
that the select-icmp instructions are in the same block and asserted on it.
The fix explicitly checks for that condition and conservatively suppresses
the optimization when it is violated.

llvm-svn: 218735

In special cases select instructions can be eliminated by
replacing them with a cheaper bitwise operation even when the
select result is used outside its home block. The instances implemented
are patterns like
    %x=icmp.eq
    %y=select %x,%r, null
    %z=icmp.eq|neq %y, null
    br %z,true, false
==> %x=icmp.ne
    %y=icmp.eq %r,null
    %z=or %x,%y
    br %z,true,false
The optimization is integrated into the instruction
combiner and performed only when all uses of the select result can
be replaced by the select operand proper. For this dominator information
is used and dominance is now a required analysis pass in the combiner.
The optimization itself is iterative. The critical step is to replace the
select result with the non-constant select operand. So the select becomes
local and the combiner iteratively works out simpler code pattern and
eventually eliminates the select.

rdar://17853760

llvm-svn: 218721

Summary:
This patch adds a threshold that controls the number of bonus instructions
allowed for folding branches with common destination. The original code allows
at most one bonus instruction. With this patch, users can customize the
threshold to allow multiple bonus instructions. The default threshold is still
1, so that the code behaves the same as before when users do not specify this
threshold.

The motivation of this change is that tuning this threshold significantly (up
to 25%) improves the performance of some CUDA programs in our internal code
base. In general, branch instructions are very expensive for GPU programs.
Therefore, it is sometimes worth trading more arithmetic computation for a more
straightened control flow. Here's a reduced example:

  __global__ void foo(int a, int b, int c, int d, int e, int n,
                      const int *input, int *output) {
    int sum = 0;
    for (int i = 0; i < n; ++i)
      sum += (((i ^ a) > b) && (((i | c ) ^ d) > e)) ? 0 : input[i];
    *output = sum;
  }

The select statement in the loop body translates to two branch instructions "if
((i ^ a) > b)" and "if (((i | c) ^ d) > e)" which share a common destination.
With the default threshold, SimplifyCFG is unable to fold them, because
computing the condition of the second branch "(i | c) ^ d > e" requires two
bonus instructions. With the threshold increased, SimplifyCFG can fold the two
branches so that the loop body contains only one branch, making the code
conceptually look like:

  sum += (((i ^ a) > b) & (((i | c ) ^ d) > e)) ? 0 : input[i];

Increasing the threshold significantly improves the performance of this
particular example. In the configuration where both conditions are guaranteed
to be true, increasing the threshold from 1 to 2 improves the performance by
18.24%. Even in the configuration where the first condition is false and the
second condition is true, which favors shortcuts, increasing the threshold from
1 to 2 still improves the performance by 4.35%.

We are still looking for a good threshold and maybe a better cost model than
just counting the number of bonus instructions. However, according to the above
numbers, we think it is at least worth adding a threshold to enable more
experiments and tuning. Let me know what you think. Thanks!

Test Plan: Added one test case to check the threshold is in effect

Reviewers: nadav, eliben, meheff, resistor, hfinkel

Reviewed By: hfinkel

Subscribers: hfinkel, llvm-commits

Differential Revision: http://reviews.llvm.org/D5529

llvm-svn: 218711

Differential Revision: http://reviews.llvm.org/D5412

llvm-svn: 218671

This patch extends r217953 to handle unsigned comparison.
Phabricator revision: http://reviews.llvm.org/D5526

llvm-svn: 218659