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331ec379a0
Prior to this commit, physical registers defined implicitly were considered free right after their definition, i.e.. like dead definitions. Therefore, their uses had to immediately follow their definitions, otherwise the related register may be reused to allocate a virtual register. This commit fixes this assumption by keeping implicit definitions alive until they are actually used. The downside is that if the implicit definition was dead (and not marked at such), we block an otherwise available register. This is however conservatively correct and makes the fast register allocator much more robust in particular regarding the scheduling of the instructions. Fixes PR21700. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223317 91177308-0d34-0410-b5e6-96231b3b80d8
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