Merging r293025:

Merging r293025:
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r293025 | ahatanak | 2017-01-24 22:21:51 -0800 (Tue, 24 Jan 2017) | 29 lines

[SimplifyCFG] Do not sink and merge inline-asm instructions.

Conservatively disable sinking and merging inline-asm instructions as doing so
can potentially create arguments that cannot satisfy the inline-asm constraints.

For example, SimplifyCFG used to do the following transformation:

(before)
if.then:
  %0 = call i32 asm "rorl $2, $0", "=&r,0,n"(i32 %r6, i32 8)
  br label %if.end
if.else:
  %1 = call i32 asm "rorl $2, $0", "=&r,0,n"(i32 %r6, i32 6)
  br label %if.end

(after)
  %.sink = select i1 %tobool, i32 6, i32 8
  %0 = call i32 asm "rorl $2, $0", "=&r,0,n"(i32 %r6, i32 %.sink)

This would result in a crash in the backend since only immediate integer operands
are permitted for constraint "n".

rdar://problem/30110806

Differential Revision: https://reviews.llvm.org/D29111

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_40@293074 91177308-0d34-0410-b5e6-96231b3b80d8