llvm/include
Matthias Braun e5c4e28d9c CodeGen: Add DetectDeadLanes pass.
The DetectDeadLanes pass performs a dataflow analysis of used/defined
subregister lanes across COPY instructions and instructions that will
get lowered to copies. It detects dead definitions and uses reading
undefined values which are obscured by COPY and subregister usage.

These dead definitions cause trouble in the register coalescer which
cannot deal with definitions suddenly becoming dead after coalescing
COPY instructions.

For now the pass only adds dead and undef flags to machine operands. It
should be possible to extend it in the future to remove the dead
instructions and redo the analysis for the affected virtual
registers.

Differential Revision: http://reviews.llvm.org/D18427

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@267851 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-28 03:07:16 +00:00
..
llvm CodeGen: Add DetectDeadLanes pass. 2016-04-28 03:07:16 +00:00
llvm-c [ORC] clang-format code that was touched in r267457. NFC. 2016-04-25 21:21:20 +00:00