[X86] Avoid introducing extra shuffles when lowering packed vector shifts.

When lowering a vector shift node, the backend checks if the shift count is a
shuffle with a splat mask. If so, then it introduces an extra dag node to
extract the splat value from the shuffle. The splat value is then used
to generate a shift count of a target specific shift.

However, if we know that the shift count is a splat shuffle, we can use the
splat index 'I' to extract the I-th element from the first shuffle operand.
The advantage is that the splat shuffle may become dead since we no longer
use it.

Example:

;;
define <4 x i32> @example(<4 x i32> %a, <4 x i32> %b) {
  %c = shufflevector <4 x i32> %b, <4 x i32> undef, <4 x i32> zeroinitializer
  %shl = shl <4 x i32> %a, %c
  ret <4 x i32> %shl
}
;;

Before this patch, llc generated the following code (-mattr=+avx):
  vpshufd $0, %xmm1, %xmm1   # xmm1 = xmm1[0,0,0,0]
  vpxor  %xmm2, %xmm2
  vpblendw $3, %xmm1, %xmm2, %xmm1 # xmm1 = xmm1[0,1],xmm2[2,3,4,5,6,7]
  vpslld %xmm1, %xmm0, %xmm0
  retq

With this patch, the redundant splat operation is removed from the code.
  vpxor  %xmm2, %xmm2
  vpblendw $3, %xmm1, %xmm2, %xmm1 # xmm1 = xmm1[0,1],xmm2[2,3,4,5,6,7]
  vpslld %xmm1, %xmm0, %xmm0
  retq


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223461 91177308-0d34-0410-b5e6-96231b3b80d8
[msan] Avoid extra origin address realignment.

Do not realign origin address if the corresponding application
address is at least 4-byte-aligned.

Saves 2.5% code size in track-origins mode.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223464 91177308-0d34-0410-b5e6-96231b3b80d8
Use an early return. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223470 91177308-0d34-0410-b5e6-96231b3b80d8
Fix typos in llvm/IR/Module.h
Phabricator revision: http://reviews.llvm.org/D6535

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223472 91177308-0d34-0410-b5e6-96231b3b80d8
Update TargetTriple format info.
Phabricator revision: http://reviews.llvm.org/D6543

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223473 91177308-0d34-0410-b5e6-96231b3b80d8
Small cleanup on how we clear constant variables. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223474 91177308-0d34-0410-b5e6-96231b3b80d8
Improvements to ARM assembler tests

No functional changes. Got myself bitten in r223113 when adding support for
modified immediate syntax (regressions reported by joerg@britannica.bec.de,
fixes in r223366 and r223381). Our assembler tests did not cover serveral
different syntax variants. This patch expands the test coverage to check for
the following cases:

1. Modified immediate operands may be expressed with expressions, as in #(4 * 2)
instead of #8.

2. Modified immediate operands may be _optionally_ prefixed by a '#' symbol or a
'$' symbol.

3. Certain instructions (e.g. ADD) support single input register variants;
[ADD r0, #mod_imm] is same as [ADD r0, r0, #mod_imm].

4. Certain instructions have aliases which convert plain immediates to modified
immediates. For an example, [ADD r0, -10] is not valid because -10 (in two's
complement) cannot be encoded as a modified immediate, but ARMInstrInfo.td
defines an alias which can transform this into a [SUB r0, 10].

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223475 91177308-0d34-0410-b5e6-96231b3b80d8
LLVMContext: Store APInt/APFloat directly into the ConstantInt/FP DenseMaps.

Required some APInt massaging to get proper empty/tombstone values. Apart
from making the code a bit simpler this also reduces the bucket size of
the ConstantInt map from 32 to 24 bytes.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223478 91177308-0d34-0410-b5e6-96231b3b80d8
Be less conservative about when we build the gold plugin.

It is only build if LLVM_BINUTILS_INCDIR is explicitly given, so there is
no point in having extra restrictions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223481 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Marking several instructions as isCodeGenOnly=0 and adding direct disassembly tests for many instructions.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223482 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Adding combine reg-reg forms.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223485 91177308-0d34-0410-b5e6-96231b3b80d8
Refactor duplicated code. NFC.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223486 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] [NFC] Rearranging def order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223487 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] [NFC] Rearranging patterns and mux instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223488 91177308-0d34-0410-b5e6-96231b3b80d8
[CodeGenPrepare] Use variables for reused values. NFC.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223491 91177308-0d34-0410-b5e6-96231b3b80d8
Regenerate this stale testcase from source.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223492 91177308-0d34-0410-b5e6-96231b3b80d8
Fix a bug when pretty-printing DW_OP_deref.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223493 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Adding DoubleRegs decoder.  Moving C2_mux and A2_nop.  Adding combine imm-imm form.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223494 91177308-0d34-0410-b5e6-96231b3b80d8
BFI: Saturate when combining edges to a successor

When a loop gets bundled up, its outgoing edges are quite large, and can
just barely overflow 64-bits.  If one successor has multiple incoming
edges -- and that successor is getting all the incoming mass --
combining just its edges can overflow.  Handle that by saturating rather
than asserting.

This fixes PR21622.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223500 91177308-0d34-0410-b5e6-96231b3b80d8
These two calls were grabbing the same register info. Unify them.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223502 91177308-0d34-0410-b5e6-96231b3b80d8