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| author | Matthias Braun <matze@braunis.de> | 2016-07-09 00:19:07 +0000 |
|---|---|---|
| committer | Matthias Braun <matze@braunis.de> | 2016-07-09 00:19:07 +0000 |
| commit | 152e7c8b1222d2af61df72c08caaa740e553cb6c (patch) | |
| tree | 7178c1d1db0b5bf2babca7793c71c079854e1156 /clang/lib/CodeGen/CodeGenModule.cpp | |
| parent | 07985809abeb97c131d37ee389ee0fea2a646516 (diff) | |
| download | llvm-152e7c8b1222d2af61df72c08caaa740e553cb6c.zip llvm-152e7c8b1222d2af61df72c08caaa740e553cb6c.tar.gz llvm-152e7c8b1222d2af61df72c08caaa740e553cb6c.tar.bz2 | |
VirtRegMap: Replace some identity copies with KILL instructions.
An identity COPY like this:
%AL = COPY %AL, %EAX<imp-def>
has no semantic effect, but encodes liveness information: Further users
of %EAX only depend on this instruction even though it does not define
the full register.
Replace the COPY with a KILL instruction in those cases to maintain this
liveness information. (This reverts a small part of r238588 but this
time adds a comment explaining why a KILL instruction is useful).
llvm-svn: 274952
Diffstat (limited to 'clang/lib/CodeGen/CodeGenModule.cpp')
0 files changed, 0 insertions, 0 deletions