llvm-project/llvm
Sameer Sahasrabuddhe 3cbbded68c Introduce unify-loop-exits pass.
For each natural loop with multiple exit blocks, this pass creates a
new block N such that all exiting blocks now branch to N, and then
control flow is redistributed to all the original exit blocks.

The bulk of the tranformation is a new function introduced in
BasicBlockUtils that an redirect control flow from a set of incoming
blocks to a set of outgoing blocks via a common "hub".

This is a useful workaround for a limitation in the structurizer which
incorrectly orders blocks when processing a nest of loops. This pass
bypasses that issue by ensuring that each natural loop is recognized
as a separate region. Since the structurizer is a region pass, it no
longer sees a nest of loops in a single region, and instead processes
each "level" in the nesting as a separate region.

The AMDGPU backend provides a new option to enable this pass before
the structurizer, which may eventually be enabled by default.

Reviewers: madhur13490, arsenm, nhaehnle

Reviewed By: nhaehnle

Differential Revision: https://reviews.llvm.org/D75865
2020-03-30 13:23:56 -04:00
..
benchmarks
bindings Add an SDK attribute to DICompileUnit 2020-03-11 14:14:06 -07:00
cmake Do export symbols when LLVM_EXPORT_SYMBOLS_FOR_PLUGINS is on. 2020-03-26 09:07:02 +00:00
docs [LangRef] Clarify the semantics of branch on undef 2020-03-30 11:41:47 +09:00
examples [examples] Fixes for BUILD_SHARED_LIBS=on 2020-03-23 15:21:45 -07:00
include Introduce unify-loop-exits pass. 2020-03-30 13:23:56 -04:00
lib Introduce unify-loop-exits pass. 2020-03-30 13:23:56 -04:00
projects
resources
runtimes [runtimes] When COMPILER_RT is enabled, consider SANITIZER prefixes 2020-03-11 14:22:20 -07:00
test Introduce unify-loop-exits pass. 2020-03-30 13:23:56 -04:00
tools Introduce unify-loop-exits pass. 2020-03-30 13:23:56 -04:00
unittests [Alignment][NFC] Use Align version of getMachineMemOperand 2020-03-30 15:46:27 +00:00
utils [gn build] Port 854f268ca6 2020-03-29 19:24:34 +00:00
.clang-format
.clang-tidy
.gitattributes
.gitignore
CMakeLists.txt [cmake] Fix -stripped for umbrella library install targets 2020-03-20 18:46:48 -07:00
CODE_OWNERS.TXT
CREDITS.TXT
LICENSE.TXT
LLVMBuild.txt
README.txt Test commit. 2020-03-14 18:08:26 -07:00
RELEASE_TESTERS.TXT
configure
llvm.spec.in

README.txt

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