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dim
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2017-04-21T17:03:48.187928Z
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MFC r316989:

Pull in r300404 from upstream llvm trunk (by me):

  Use correct registers for "A" inline asm constraint

  Summary:
  In PR32594, inline assembly using the 'A' constraint on x86_64 causes
  llvm to crash with a "Cannot select" stack trace.  This is because
  `X86TargetLowering::getRegForInlineAsmConstraint` hardcodes that 'A'
  means the EAX and EDX registers.

  However, on x86_64 it means the RAX and RDX registers, and on 16-bit
  x86 (ia16?) it means the old AX and DX registers.

  Add new register classes in `X86RegisterInfo.td` to support these
  cases, and amend the logic in `getRegForInlineAsmConstraint` to cope
  with different subtargets.  Also add a test case, derived from
  PR32594.

  Reviewers: craig.topper, qcolombet, RKSimon, ab

  Reviewed By: ab

  Subscribers: ab, emaste, royger, llvm-commits

  Differential Revision: https://reviews.llvm.org/D31902

This should fix crashes when using the 'A' constraint on amd64, for
example as it is being used in Xen.

Reported by:	royger

MFC r317079:

Pull in r300429 from upstream llvm trunk (by Benjamin Kramer):

  [X86] Remove special handling for 16 bit for A asm constraints.

  Our 16 bit support is assembler-only + the terrible hack that is
  .code16gcc. Simply using 32 bit registers does the right thing for
  the latter.

  Fixes PR32681.

This fixes some cases of assembling 16 bit code (i.e. SeaBIOS) that uses
the 'A' inline asm constraint, after r316989.

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