Improved fix for PR17827 (instcombine of shift/and/compare).

This change fixes the case of arithmetic shift right - do not attempt to fold that case.
This change also relaxes the conditions when attempting to fold the logical shift right and shift left cases.

No additional IR-level test cases included at this time. See http://llvm.org/bugs/show_bug.cgi?id=17827 for proofs that these are correct transformations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197705 91177308-0d34-0410-b5e6-96231b3b80d8
Add a finishParse() callback to the targer asm parser

This callback is invoked when the parse has finished successfuly. It
will be used to write out ARM constant pools to implement the ldr
pseudo.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197706 91177308-0d34-0410-b5e6-96231b3b80d8
Implement the ldr-pseudo opcode for ARM assembly

The ldr-pseudo opcode is a convenience for loading 32-bit constants.
It is converted into a pc-relative load from a constant pool. For
example,

  ldr r0, =0x10001
  ldr r1, =bar

will generate this output in the final assembly

  ldr r0, .Ltmp0
  ldr r1, .Ltmp1
  ...
  .Ltmp0: .long 0x10001
  .Ltmp1: .long bar

Sketch of the LDR pseudo implementation:
  Keep a map from Section => ConstantPool

  When parsing ldr r0, =val
    parse val as an MCExpr
    get ConstantPool for current Section
    Label = CreateTempSymbol()
    remember val in ConstantPool at next free slot
    add operand to ldr that is MCSymbolRef of Label

  On finishParse() callback
    Write out all non-empty constant pools
    for each Entry in ConstantPool
      Emit Entry.Label
      Emit Entry.Value

Possible improvements to be added in a later patch:
  1. Does not convert load of small constants to mov
     (e.g. ldr r0, =0x1 => mov r0, 0x1)
  2. Does reuse constant pool entries for same constant

The implementation was tested for ARM, Thumb1, and Thumb2 targets on
linux and darwin.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197708 91177308-0d34-0410-b5e6-96231b3b80d8
Unbreak ARM buildbots after r197653 by forcing the target triple on this test.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197709 91177308-0d34-0410-b5e6-96231b3b80d8
Implement the .ltorg directive for ARM assembly

This directive will write out the assembler-maintained constant
pool for the current section. These constant pools are created to
support the ldr-pseudo instruction (e.g. ldr r0, =val).

The directive can be used by the programmer to place the constant
pool in a location that can be reached by a pc-relative offset in
the ldr instruction.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197711 91177308-0d34-0410-b5e6-96231b3b80d8
[X86][fast-isel] Fix select lowering.
The condition in selects is supposed to be i1.
Make sure we are just reading the less significant bit
of the 8 bits width value to match this constraint.

<rdar://problem/15651765>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197712 91177308-0d34-0410-b5e6-96231b3b80d8
Stay classy (and legal) LLVM. Remove links to 3rd party SMT solver whose links may not be permanent.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@197713 91177308-0d34-0410-b5e6-96231b3b80d8