Retry commit r200022 with a fix for the build bot errors. Constant expressions
have (unlike instructions) module scope use lists and therefore may have users
in different functions. The fix is to simply ignore these out-of-function uses.

llvm-svn: 200034

PR18600.

llvm-svn: 200028

This reverts commit r200022 to unbreak the build bots.

llvm-svn: 200024

This pass identifies expensive constants to hoist and coalesces them to
better prepare it for SelectionDAG-based code generation. This works around the
limitations of the basic-block-at-a-time approach.

First it scans all instructions for integer constants and calculates its
cost. If the constant can be folded into the instruction (the cost is
TCC_Free) or the cost is just a simple operation (TCC_BASIC), then we don't
consider it expensive and leave it alone. This is the default behavior and
the default implementation of getIntImmCost will always return TCC_Free.

If the cost is more than TCC_BASIC, then the integer constant can't be folded
into the instruction and it might be beneficial to hoist the constant.
Similar constants are coalesced to reduce register pressure and
materialization code.

When a constant is hoisted, it is also hidden behind a bitcast to force it to
be live-out of the basic block. Otherwise the constant would be just
duplicated and each basic block would have its own copy in the SelectionDAG.
The SelectionDAG recognizes such constants as opaque and doesn't perform
certain transformations on them, which would create a new expensive constant.

This optimization is only applied to integer constants in instructions and
simple (this means not nested) constant cast experessions. For example:
%0 = load i64* inttoptr (i64 big_constant to i64*)

Reviewed by Eric

llvm-svn: 200022

Sweep the codebase for common typos. Includes some changes to visible function
names that were misspelt.

llvm-svn: 200018

We completely skipped promotion in LICM if the loop has a preheader or
dedicated exits, but not *both*. We hoist if there is a preheader, and
sink if there are dedicated exits, but either hoisting or sinking can
move loop invariant code out of the loop!

I have no idea if this has a practical consequence. If anyone has ideas
for a test case, let me know.

llvm-svn: 199966

literal that bakes a pass name and forces parsing it in the pass
manager.

llvm-svn: 199963

Argument promotion can replace an argument of a call with an alloca. This
requires clearing the tail marker as it is very likely that the callee is now
using an alloca in the caller.

This fixes pr14710.

llvm-svn: 199909

function and a FunctionPass.

This has many benefits. The motivating use case was to be able to
compute function analysis passes *after* running LoopSimplify (to avoid
invalidating them) and then to run other passes which require
LoopSimplify. Specifically passes like unrolling and vectorization are
critical to wire up to BranchProbabilityInfo and BlockFrequencyInfo so
that they can be profile aware. For the LoopVectorize pass the only
things in the way are LoopSimplify and LCSSA. This fixes LoopSimplify
and LCSSA is next on my list.

There are also a bunch of other benefits of doing this:
- It is now very feasible to make more passes *preserve* LoopSimplify
  because they can simply run it after changing a loop. Because
  subsequence passes can assume LoopSimplify is preserved we can reduce
  the runs of this pass to the times when we actually mutate a loop
  structure.
- The new pass manager should be able to more easily support loop passes
  factored in this way.
- We can at long, long last observe that LoopSimplify is preserved
  across SCEV. This *halves* the number of times we run LoopSimplify!!!

Now, getting here wasn't trivial. First off, the interfaces used by
LoopSimplify are all over the map regarding how analysis are updated. We
end up with weird "pass" parameters as a consequence. I'll try to clean
at least some of this up later -- I'll have to have it all clean for the
new pass manager.

Next up I discovered a really frustrating bug. LoopUnroll *claims* to
preserve LoopSimplify. That's actually a lie. But the way the
LoopPassManager ends up running the passes, it always ran LoopSimplify
on the unrolled-into loop, rectifying this oversight before any
verification could kick in and point out that in fact nothing was
preserved. So I've added code to the unroller to *actually* simplify the
surrounding loop when it succeeds at unrolling.

The only functional change in the test suite is that we now catch a case
that was previously missed because SCEV and other loop transforms see
their containing loops as simplified and thus don't miss some
opportunities. One test case has been converted to check that we catch
this case rather than checking that we miss it but at least don't get
the wrong answer.

Note that I have #if-ed out all of the verification logic in
LoopSimplify! This is a temporary workaround while extracting these bits
from the LoopPassManager. Currently, there is no way to have a pass in
the LoopPassManager which preserves LoopSimplify along with one which
does not. The LPM will try to verify on each loop in the nest that
LoopSimplify holds but the now-Function-pass cannot distinguish what
loop is being verified and so must try to verify all of them. The inner
most loop is clearly no longer simplified as there is a pass which
didn't even *attempt* to preserve it. =/ Once I get LCSSA out (and maybe
LoopVectorize and some other fixes) I'll be able to re-enable this check
and catch any places where we are still failing to preserve
LoopSimplify. If this causes problems I can back this out and try to
commit *all* of this at once, but so far this seems to work and allow
much more incremental progress.

llvm-svn: 199884

llvm-svn: 199836

llvm-svn: 199801

inconsistent results for different orderings of alloca slices. The
fundamental issue is that it is just always a mistake to return early
from this function. There is no effective early exit to leverage. This
patch stops trynig to do so and simplifies the code a bit as
a consequence.

Original diagnosis and patch by James Molloy with some name tweaks by me
in part reflecting feedback from Duncan Smith on the mailing list.

llvm-svn: 199771

Fix all the remaining lost-fast-math-flags bugs I've been able to find.  The most important of these are cases in the generic logic for combining BinaryOperators.
This logic hadn't been updated to handle FastMathFlags, and it took me a while to detect it because it doesn't show up in a simple search for CreateFAdd.

llvm-svn: 199629

Also make them vector-aware.

llvm-svn: 199608

llvm-svn: 199605

llvm-svn: 199604

llvm-svn: 199602

llvm-svn: 199598

intrinsics.

Reported on the list by Evan with a couple of attempts to fix, but it
took a while to dig down to the root cause. There are two overlapping
bugs here, both centering around the circumstance of discovering
a memcpy operand which is known to be completely outside the bounds of
the alloca.

First, we need to kill the *other* side of the memcpy if it was added to
this alloca. Otherwise we'll factor it into our slicing and try to
rewrite it even though we know for a fact that it is dead. This is made
more tricky because we can visit the sides in either order. So we have
to both kill the other side and skip instructions marked as dead. The
latter really should be goodness in every case, but here is a matter of
correctness.

Second, we need to actually remove the *uses* of the alloca by the
memcpy when queuing it for later deletion. Otherwise it may still be
using the alloca when we go to promote it (if the rewrite re-uses the
existing alloca instruction). Do this by factoring out the
use-clobbering used when for nixing a Phi argument and re-using it
across the operands of a to-be-deleted instruction.

llvm-svn: 199590

a reduction.

Really. Under certain circumstances (the use list of an instruction has to be
set up right - hence the extra pass in the test case) we would not recognize
when a value in a potential reduction cycle was used multiple times by the
reduction cycle.

Fixes PR18526.
radar://15851149

llvm-svn: 199570

Don't refuse to transform constexpr(call(arg, ...)) to call(constexpr(arg), ...)) just because the function has multiple return values even if their return types are the same. Patch by Eduard Burtescu!

llvm-svn: 199564

PR18532.

llvm-svn: 199553

Fix more instances of dropped fast math flags when optimizing FADD instructions.  All found by inspection (aka grep).

llvm-svn: 199528

 - add a mode for collecting per-block coverage (-asan-coverage=2).
   So far the implementation is naive (all blocks are instrumented),
   the performance overhead on top of asan could be as high as 30%.
 - Make sure the one-time calls to __sanitizer_cov are moved to function buttom,
   which in turn required to copy the original debug info into the call insn.

Here is the performance data on SPEC 2006
(train data, comparing asan with asan-coverage={0,1,2}):

                             asan+cov0     asan+cov1      diff 0-1    asan+cov2       diff 0-2      diff 1-2
       400.perlbench,        65.60,        65.80,         1.00,        76.20,         1.16,         1.16
           401.bzip2,        65.10,        65.50,         1.01,        75.90,         1.17,         1.16
             403.gcc,         1.64,         1.69,         1.03,         2.04,         1.24,         1.21
             429.mcf,        21.90,        22.60,         1.03,        23.20,         1.06,         1.03
           445.gobmk,       166.00,       169.00,         1.02,       205.00,         1.23,         1.21
           456.hmmer,        88.30,        87.90,         1.00,        91.00,         1.03,         1.04
           458.sjeng,       210.00,       222.00,         1.06,       258.00,         1.23,         1.16
      462.libquantum,         1.73,         1.75,         1.01,         2.11,         1.22,         1.21
         464.h264ref,       147.00,       152.00,         1.03,       160.00,         1.09,         1.05
         471.omnetpp,       115.00,       116.00,         1.01,       140.00,         1.22,         1.21
           473.astar,       133.00,       131.00,         0.98,       142.00,         1.07,         1.08
       483.xalancbmk,       118.00,       120.00,         1.02,       154.00,         1.31,         1.28
            433.milc,        19.80,        20.00,         1.01,        20.10,         1.02,         1.01
            444.namd,        16.20,        16.20,         1.00,        17.60,         1.09,         1.09
          447.dealII,        41.80,        42.20,         1.01,        43.50,         1.04,         1.03
          450.soplex,         7.51,         7.82,         1.04,         8.25,         1.10,         1.05
          453.povray,        14.00,        14.40,         1.03,        15.80,         1.13,         1.10
             470.lbm,        33.30,        34.10,         1.02,        34.10,         1.02,         1.00
         482.sphinx3,        12.40,        12.30,         0.99,        13.00,         1.05,         1.06

llvm-svn: 199488

When registering a pass, a pass can now specify a second construct that takes as
argument a pointer to TargetMachine.
The PassInfo class has been updated to reflect that possibility.
If such a constructor exists opt will use it instead of the default constructor
when instantiating the pass.

Since such IR passes are supposed to be rare, no specific support has been
added to this commit to allow an easy registration of such a pass.
In other words, for such pass, the initialization function has to be
hand-written (see CodeGenPrepare for instance).

Now, codegenprepare can be tested using opt:
opt -codegenprepare -mtriple=mytriple input.ll

llvm-svn: 199430

llvm-svn: 199427

Fix an instance where we would drop fast math flags when performing an fdiv to reciprocal multiply transformation.

llvm-svn: 199425

Fix a bug in InstCombine where we failed to preserve fast math flags when optimizing an FMUL expression.

llvm-svn: 199424

Teach InstCombine that (fmul X, -1.0) can be simplified to (fneg X), which LLVM expresses as (fsub -0.0, X).

llvm-svn: 199420

flag from clang, and disable zero-base shadow support on all platforms
where it is not the default behavior.

- It is completely unused, as far as we know.
- It is ABI-incompatible with non-zero-base shadow, which means all
objects in a process must be built with the same setting. Failing to
do so results in a segmentation fault at runtime.
- It introduces a backward dependency of compiler-rt on user code,
which is uncommon and complicates testing.

This is the LLVM part of a larger change.

llvm-svn: 199371

There has been an old FIXME to find the right cut-off for when it's worth
analyzing and potentially transforming a switch to a lookup table.

The switches always have two or more cases. I could not measure any speed-up
by transforming a switch with two cases. A switch with three cases gets a nice
speed-up, and I couldn't measure any compile-time regression, so I think this
is the right threshold.

In a Clang self-host, this causes 480 new switches to be transformed,
and reduces the final binary size with 8 KB.

llvm-svn: 199294

strides

Fixes PR18480.

llvm-svn: 199291

llvm-svn: 199254

Bitcasts can't be between address spaces anymore.

llvm-svn: 199253

llvm-svn: 199246

Reapply r199191, reverted in r199197 because it carelessly broke
Other/link-opts.ll.  The problem was that calling
createInternalizePass("main") would select
createInternalizePass(bool("main")) instead of
createInternalizePass(ArrayRef<const char *>("main")).  This commit
fixes the bug.

The original commit message follows.

Add API to LTOCodeGenerator to specify a strategy for the -internalize
pass.

This is a new attempt at Bill's change in r185882, which he reverted in
r188029 due to problems with the gold linker.  This puts the onus on the
linker to decide whether (and what) to internalize.

In particular, running internalize before outputting an object file may
change a 'weak' symbol into an internal one, even though that symbol
could be needed by an external object file --- e.g., with arclite.

This patch enables three strategies:

- LTO_INTERNALIZE_FULL: the default (and the old behaviour).
- LTO_INTERNALIZE_NONE: skip -internalize.
- LTO_INTERNALIZE_HIDDEN: only -internalize symbols with hidden
  visibility.

LTO_INTERNALIZE_FULL should be used when linking an executable.

Outputting an object file (e.g., via ld -r) is more complicated, and
depends on whether hidden symbols should be internalized.  E.g., for
ld -r, LTO_INTERNALIZE_NONE can be used when -keep_private_externs, and
LTO_INTERNALIZE_HIDDEN can be used otherwise.  However,
LTO_INTERNALIZE_FULL is inappropriate, since the output object file will
eventually need to link with others.

lto_codegen_set_internalize_strategy() sets the strategy for subsequent
calls to lto_codegen_write_merged_modules() and lto_codegen_compile*().

<rdar://problem/14334895>

llvm-svn: 199244

Representing dllexport/dllimport as distinct linkage types prevents using
these attributes on templates and inline functions.

Instead of introducing further mixed linkage types to include linkonce and
weak ODR, the old import/export linkage types are replaced with a new
separate visibility-like specifier:

  define available_externally dllimport void @f() {}
  @Var = dllexport global i32 1, align 4

Linkage for dllexported globals and functions is now equal to their linkage
without dllexport. Imported globals and functions must be either
declarations with external linkage, or definitions with
AvailableExternallyLinkage.

llvm-svn: 199218

Revert this for now until I fix an issue in Clang with it.

This reverts commit r199204.

llvm-svn: 199207

Representing dllexport/dllimport as distinct linkage types prevents using
these attributes on templates and inline functions.

Instead of introducing further mixed linkage types to include linkonce and
weak ODR, the old import/export linkage types are replaced with a new
separate visibility-like specifier:

  define available_externally dllimport void @f() {}
  @Var = dllexport global i32 1, align 4

Linkage for dllexported globals and functions is now equal to their linkage
without dllexport. Imported globals and functions must be either
declarations with external linkage, or definitions with
AvailableExternallyLinkage.

llvm-svn: 199204

Please update also Other/link-opts.ll, in next time.

llvm-svn: 199197