Move getNonexecutableStackSection up to the base ELF class.

The .note.GNU-stack section is not SystemZ/X86 specific.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219796 91177308-0d34-0410-b5e6-96231b3b80d8
DI: Use a `DenseMap` instead of named metadata, NFC

Remove a strange round-trip through named metadata to assign preserved
local variables to their subprograms.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219798 91177308-0d34-0410-b5e6-96231b3b80d8
Simplify handling of --noexecstack by using getNonexecutableStackSection.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219799 91177308-0d34-0410-b5e6-96231b3b80d8
DI: Cleanup comments, NFC

A number of comment cleanups:

  - Remove duplicated function and class names from comments.

  - Remove duplicated comments from source file (some of which were
    out-of-sync).

  - Move any unduplicated comments from source file to header.

  - Remove some noisy comments entirely (e.g., a comment for
    `DIDescriptor::print()` saying "print descriptor" just gets in the
    way of reading the code).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219801 91177308-0d34-0410-b5e6-96231b3b80d8
remove function names from comments; NFC


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219803 91177308-0d34-0410-b5e6-96231b3b80d8
Use 'auto' for easier reading; no functional change intended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219804 91177308-0d34-0410-b5e6-96231b3b80d8
DI: Make comments "brief"-er, NFC

Follow-up to r219801.  Post-commit review pointed out that all comments
require a `\brief` description [1], so I converted many and recrafted a
few to be briefer or to include a brief intro.  (If I'm going to clean
them up, I should do it right!)

[1]: http://llvm.org/docs/CodingStandards.html#doxygen-use-in-documentation-comments

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219808 91177308-0d34-0410-b5e6-96231b3b80d8
[MC] Make bundle alignment mode setting idempotent and support nested bundles

Summary:
Currently an error is thrown if bundle alignment mode is set more than once
per module (either via the API or the .bundle_align_mode directive). This
change allows setting it multiple times as long as the alignment doesn't
change.

Also nested bundle_lock groups are currently not allowed. This change allows
them, with the effect that the group stays open until all nests are exited,
and if any of the bundle_lock directives has the align_to_end flag, the
group becomes align_to_end.

These changes make the bundle aligment simpler to use in the compiler, and
also better match the corresponding support in GNU as.

Reviewers: jvoung, eliben

Differential Revision: http://reviews.llvm.org/D5801

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219811 91177308-0d34-0410-b5e6-96231b3b80d8
Treat the WorkSet used to find ephemeral values as double-ended

We need to make sure that we visit all operands of an instruction before moving
deeper in the operand graph. We had been pushing operands onto the back of the work
set, and popping them off the back as well, meaning that we might visit an
instruction before visiting all of its uses that sit in between it and the call
to @llvm.assume.

To provide an explicit example, given the following:
  %q0 = extractelement <4 x float> %rd, i32 0
  %q1 = extractelement <4 x float> %rd, i32 1
  %q2 = extractelement <4 x float> %rd, i32 2
  %q3 = extractelement <4 x float> %rd, i32 3
  %q4 = fadd float %q0, %q1
  %q5 = fadd float %q2, %q3
  %q6 = fadd float %q4, %q5
  %qi = fcmp olt float %q6, %q5
  call void @llvm.assume(i1 %qi)

%q5 is used by both %qi and %q6. When we visit %qi, it will be marked as
ephemeral, and we'll queue %q6 and %q5. %q6 will be marked as ephemeral and
we'll queue %q4 and %q5. Under the old system, we'd then visit %q4, which
would become ephemeral, %q1 and then %q0, which would become ephemeral as
well, and now we have a problem. We'd visit %rd, but it would not be marked as
ephemeral because we've not yet visited %q2 and %q3 (because we've not yet
visited %q5).

This will be covered by a test case in a follow-up commit that enables
ephemeral-value awareness in the SLP vectorizer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219815 91177308-0d34-0410-b5e6-96231b3b80d8
[SLPVectorize] Basic ephemeral-value awareness

The SLP vectorizer should not vectorize ephemeral values. These are used to
express information to the optimizer, and vectorizing them does not lead to
faster code (because the ephemeral values are dropped prior to code generation,
vectorized or not), and obscures the information the instructions are
attempting to communicate (the logic that interprets the arguments to
@llvm.assume generically does not understand vectorized conditions).

Also, uses by ephemeral values are free (because they, and the necessary
extractelement instructions, will be dropped prior to code generation).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219816 91177308-0d34-0410-b5e6-96231b3b80d8
correct const-ness with auto and dyn_cast

1. Use const with autos.
2. Don't bother with explicit const in cast ops because they do it automagically.

Thanks, David B. / Aaron B. / Reid K.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219817 91177308-0d34-0410-b5e6-96231b3b80d8
R600: Fix miscompiles when BFE has multiple uses

SimplifyDemandedBits would break the other uses of the operand.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219819 91177308-0d34-0410-b5e6-96231b3b80d8
R600/SI: Also try to use 0 base for misaligned 8-byte DS loads.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219823 91177308-0d34-0410-b5e6-96231b3b80d8
Enable the instruction printer in HexagonMCTargetDesc

This adds the MCInstPrinter to the LLVMHexagonDesc library and removes
the dependency LLVMHexagonAsmPrinter had on LLVMHexagonDesc. This is
a prerequisite needed by the disassembler.

Phabricator Revision: http://reviews.llvm.org/D5734

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219826 91177308-0d34-0410-b5e6-96231b3b80d8
Correctly handle references to section symbols.

When processing assembly like

.long .text

we were creating a new undefined symbol .text. GAS on the other hand would
handle that as a reference to the .text section.

This patch implements that by creating the section symbols earlier so that
they are visible during asm parsing.

The patch also updates llvm-readobj to print the symbol number in the relocation
dump so that the test can differentiate between two sections with the same name.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219829 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][AArch64] Factor out add with immediate emission into a helper function. NFC.

Simplify add with immediate emission by factoring it out into a helper function.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219830 91177308-0d34-0410-b5e6-96231b3b80d8
Reapply "[FastISel][AArch64] Add custom lowering for GEPs."

This is mostly a copy of the existing FastISel GEP code, but we have to
duplicate it for AArch64, because otherwise we would bail out even for simple
cases. This is because the standard fastEmit functions don't cover MUL at all
and ADD is lowered very inefficientily.

The original commit had a bug in the add emit logic, which has been fixed.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219831 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: Narrow switch instructions using known bits.

Truncate the operands of a switch instruction to a narrower type if the upper
bits are known to be all ones or zeros.

rdar://problem/17720004


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219832 91177308-0d34-0410-b5e6-96231b3b80d8
Add LLVM_ATTRIBUTE_UNUSED to function currently just used in an assert

Fixes break when -Wunused-function is used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219833 91177308-0d34-0410-b5e6-96231b3b80d8
Teach ScalarEvolution to sharpen range information.
    
If x is known to have the range [a, b) in a loop predicated by (icmp
ne x, a), its range can be sharpened to [a + 1, b).  Get
ScalarEvolution and hence IndVars to exploit this fact.
    
This change triggers an optimization to widen-loop-comp.ll, so it had
to be edited to get it to pass.

phabricator: http://reviews.llvm.org/D5639



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219834 91177308-0d34-0410-b5e6-96231b3b80d8