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Alina Sbirlea 029d974b53 Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred.
Summary:
Two utils methods have essentially the same functionality. This is an attempt to merge them into one.
1. lib/Transforms/Utils/Local.cpp : MergeBasicBlockIntoOnlyPred
2. lib/Transforms/Utils/BasicBlockUtils.cpp : MergeBlockIntoPredecessor

Prior to the patch:
1. MergeBasicBlockIntoOnlyPred
Updates either DomTree or DeferredDominance
Moves all instructions from Pred to BB, deletes Pred
Asserts BB has single predecessor
If address was taken, replace the block address with constant 1 (?)

2. MergeBlockIntoPredecessor
Updates DomTree, LoopInfo and MemoryDependenceResults
Moves all instruction from BB to Pred, deletes BB
Returns if doesn't have a single predecessor
Returns if BB's address was taken

After the patch:
Method 2. MergeBlockIntoPredecessor is attempting to become the new default:
Updates DomTree or DeferredDominance, and LoopInfo and MemoryDependenceResults
Moves all instruction from BB to Pred, deletes BB
Returns if doesn't have a single predecessor
Returns if BB's address was taken

Uses of MergeBasicBlockIntoOnlyPred that need to be replaced:

1. lib/Transforms/Scalar/LoopSimplifyCFG.cpp
Updated in this patch. No challenges.

2. lib/CodeGen/CodeGenPrepare.cpp
Updated in this patch.
  i. eliminateFallThrough is straightforward, but I added using a temporary array to avoid the iterator invalidation.
  ii. eliminateMostlyEmptyBlock(s) methods also now use a temporary array for blocks
Some interesting aspects:
  - Since Pred is not deleted (BB is), the entry block does not need updating.
  - The entry block was being updated with the deleted block in eliminateMostlyEmptyBlock. Added assert to make obvious that BB=SinglePred.
  - isMergingEmptyBlockProfitable assumes BB is the one to be deleted.
  - eliminateMostlyEmptyBlock(BB) does not delete BB on one path, it deletes its unique predecessor instead.
  - adding some test owner as subscribers for the interesting tests modified:
    test/CodeGen/X86/avx-cmp.ll
    test/CodeGen/AMDGPU/nested-loop-conditions.ll
    test/CodeGen/AMDGPU/si-annotate-cf.ll
    test/CodeGen/X86/hoist-spill.ll
    test/CodeGen/X86/2006-11-17-IllegalMove.ll

3. lib/Transforms/Scalar/JumpThreading.cpp
Not covered in this patch. It is the only use case using the DeferredDominance.
I would defer to Brian Rzycki to make this replacement.

Reviewers: chandlerc, spatel, davide, brzycki, bkramer, javed.absar

Subscribers: qcolombet, sanjoy, nemanjai, nhaehnle, jlebar, tpr, kbarton, RKSimon, wmi, arsenm, llvm-commits

Differential Revision: https://reviews.llvm.org/D48202

llvm-svn: 335183
2018-06-20 22:01:04 +00:00
bindings [LLVM-C] [OCaml] Remove LLVMAddBBVectorizePass 2018-05-28 16:58:10 +00:00
cmake [cmake] Change ON/OFF to YES/NO. NFC 2018-06-14 23:40:04 +00:00
docs [llvm] Document "%T" as deprecated in TestingGuide.rst 2018-06-19 22:22:48 +00:00
examples [ORC] Update JITCompileCallbackManager to support multi-threaded code. 2018-05-30 01:57:45 +00:00
include Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred. 2018-06-20 22:01:04 +00:00
lib Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred. 2018-06-20 22:01:04 +00:00
projects [cmake] Support moving debuginfo-tests to llvm/projects 2017-12-12 17:06:08 +00:00
resources
runtimes [CMake] Pass additional CMake tools to external projects 2018-06-06 21:43:37 +00:00
test Generalize MergeBlockIntoPredecessor. Replace uses of MergeBasicBlockIntoOnlyPred. 2018-06-20 22:01:04 +00:00
tools [llvm-mca] use APint::operator[] to obtain the bit value. NFC 2018-06-20 14:30:17 +00:00
unittests [llvm-exegesis] Add mechanism to add target-specific passes. 2018-06-20 11:54:35 +00:00
utils [X86] Add the ability to force an EVEX2VEX mapping table entry from the .td files. Remove remaining manual table entries from the tablegen emitter. 2018-06-19 04:24:44 +00:00
.arcconfig [llvm] Set up .arcconfig to point to Diffusion L repository 2018-01-12 15:37:41 +00:00
.clang-format
.clang-tidy .clang-tidy: correct style name is 'camelBack' not 'lowerCase'. 2016-09-13 19:04:26 +00:00
.gitattributes [DebugInfo] Add DILabel metadata and intrinsic llvm.dbg.label. 2018-05-09 02:40:45 +00:00
.gitignore gitignore: Ignore .vs folder (VS2017 config files) 2017-04-08 00:16:58 +00:00
CMakeLists.txt [CMake] Handle 'libtool' being at a path with spaces in it. 2018-06-13 18:21:47 +00:00
CODE_OWNERS.TXT [CODE_OWNERS] Update my email address. 2018-04-23 19:09:49 +00:00
configure Remove autoconf support 2016-01-26 21:29:08 +00:00
CREDITS.TXT Update my information in the CREDITS file. 2018-06-15 20:02:11 +00:00
LICENSE.TXT Update copyright year to 2018. 2018-06-18 12:22:17 +00:00
llvm.spec.in [Sparc] Implement i64 load/store support for 32-bit sparc. 2015-08-10 19:11:39 +00:00
LLVMBuild.txt
README.txt Test commit: remove a blank line 2018-06-08 21:21:55 +00:00
RELEASE_TESTERS.TXT Remove myself from the release testers list. (NFC) 2018-06-20 21:25:50 +00:00

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