[PATCH] D40042: [InstCombine] Replace metadata alloca uses without a cast

[Reid Kleckner via Phabricator via llvm-commits]

rnk created this revision.
Herald added a subscriber: hiraditya.

Changing the allocated type of an alloca requires introducing a new cast
and replacing all uses with the cast to satisfy the LLVM type system.
However, debug info (and presumably most other metadata uses) don't care
about LLVM pointee types, and would probably rather refer to the
underlying alloca instead of a bitcast. Therefore, replace the metadata
uses up front with the new alloca before doing the global replacement
with a cast.

Fixes a debug info quality issue uncovered in Chromium in
http://crbug.com/784609


https://reviews.llvm.org/D40042

Files:
  llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
  llvm/test/Transforms/InstCombine/alloca-cast-debuginfo.ll

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