Merging r354937:

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r354937 | joerg | 2019-02-27 01:40:59 +0100 (Wed, 27 Feb 2019) | 9 lines

Fix inline assembler constraint validation

The current constraint logic is both too lax and too strict. It fails
for input outside the [INT_MIN..INT_MAX] range, but it also implicitly
accepts 0 as value when it should not. Adjust logic to handle both
correctly.

Differential Revision: https://reviews.llvm.org/D58649

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llvm-svn: 355673