Reapply with DTU update moved after CFG update, which is a
requirement of the API.
-----
Non-feasible control-flow edges are currently removed by replacing
the branch condition with a constant and then calling
ConstantFoldTerminator. This happens in a rather roundabout manner,
by inspecting the users (effectively: predecessors) of unreachable
blocks, and further complicated by the need to explicitly materialize
the condition for "forced" edges. I would like to extend SCCP to
discard switch conditions that are non-feasible based on range
information, but this is incompatible with the current approach
(as there is no single constant we could use.)
Instead, this patch explicitly removes non-feasible edges. It
currently only needs to handle the case where there is a single
feasible edge. The llvm_unreachable() branch will need to be
implemented for the aforementioned switch improvement.
Differential Revision: https://reviews.llvm.org/D84264
It breaks stage-2 build. Clang crashed when compiling
llvm/lib/Target/Hexagon/HexagonFrameLowering.cpp
llvm/Support/GenericDomTree.h eraseNode: Node is not a leaf node
Non-feasible control-flow edges are currently removed by replacing
the branch condition with a constant and then calling
ConstantFoldTerminator. This happens in a rather roundabout manner,
by inspecting the users (effectively: predecessors) of unreachable
blocks, and further complicated by the need to explicitly materialize
the condition for "forced" edges. I would like to extend SCCP to
discard switch conditions that are non-feasible based on range
information, but this is incompatible with the current approach
(as there is no single constant we could use.)
Instead, this patch explicitly removes non-feasible edges. It
currently only needs to handle the case where there is a single
feasible edge. The llvm_unreachable() branch will need to be
implemented for the aforementioned switch improvement.
Differential Revision: https://reviews.llvm.org/D84264
If we fold a branch/switch to an unconditional branch to another dead block we
replace the branch with unreachable, to avoid attempting to fold the
unconditional branch.
Reviewers: davide, efriedma, mssimpso, jdoerfert
Reviewed By: jdoerfert
Differential Revision: https://reviews.llvm.org/D61300
llvm-svn: 360232
Nikita Popov