Andrew Trick fcf79528da Rotate multi-exit loops even if the latch was simplified. ... Test case by Michele Scandale! Fixes PR10293: Load not hoisted out of loop with multiple exits. There are few regressions with this patch, now tracked by rdar:13817079, and a roughly equal number of improvements. The regressions are almost certainly back luck because LoopRotate has very little idea of whether rotation is profitable. Doing better requires a more comprehensive solution. This checkin is a quick fix that lacks generality (PR10293 has a counter-example). But it trivially fixes the case in PR10293 without interfering with other cases, and it does satify the criteria that LoopRotate is a loop canonicalization pass that should avoid heuristics and special cases. I can think of two approaches that would probably be better in the long run. Ultimately they may both make sense. (1) LoopRotate should check that the current header would make a good loop guard, and that the loop does not already has a sufficient guard. The artifical SimplifiedLoopLatch check would be unnecessary, and the design would be more general and canonical. Two difficulties: - We need a strong guarantee that we won't endlessly rotate, so the analysis would need to be precise in order to avoid the SimplifiedLoopLatch precondition. - Analysis like this are usually based on SCEV, which we don't want to rely on. (2) Rotate on-demand in late loop passes. This could even be done by shoving the loop back on the queue after the optimization that needs it. This could work well when we find LICM opportunities in multi-branch loops. This requires some work, and it doesn't really solve the problem of SCEV wanting a loop guard before the analysis. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@181230 91177308-0d34-0410-b5e6-96231b3b80d8		2013-05-06 17:58:18 +00:00
..
ADCE.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
BasicBlockPlacement.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
CMakeLists.txt	Extracted ObjCARC.cpp into its own library libLLVMObjCARCOpts in preparation for refactoring the ARC Optimizer.	2013-01-28 01:35:51 +00:00
CodeGenPrepare.cpp	Fix a typo in comment.	2013-04-15 17:40:48 +00:00
ConstantProp.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
CorrelatedValuePropagation.cpp	CVP: If we have a PHI with an incoming select, try to skip the select.	2013-02-24 15:34:43 +00:00
DCE.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
DeadStoreElimination.cpp	Change GetPointerBaseWithConstantOffset's DataLayout argument from a	2013-01-31 02:00:45 +00:00
EarlyCSE.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
GlobalMerge.cpp	Clarify that llvm.used can contain aliases.	2013-04-22 14:58:02 +00:00
GVN.cpp	Decompose GVN::processNonLocalLoad() (about 400 LOC) into smaller helper functions. No function change.	2013-05-03 19:17:26 +00:00
IndVarSimplify.cpp	IndVarSimplify: do not recompute an IV value outside of the loop if :	2013-03-19 20:00:22 +00:00
JumpThreading.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
LICM.cpp	LICM: Hoist insertvalue/extractvalue out of loops.	2013-01-09 18:12:03 +00:00
LLVMBuild.txt
LoopDeletion.cpp	Make method private. Keep coding standard.	2013-03-18 23:31:30 +00:00
LoopIdiomRecognize.cpp	PR14904: Segmentation fault running pass 'Recognize loop idioms'	2013-01-10 23:32:01 +00:00
LoopInstSimplify.cpp	Remove #includes from the commonly used LoopInfo.h.	2013-02-09 01:04:28 +00:00
LoopRotation.cpp	Rotate multi-exit loops even if the latch was simplified.	2013-05-06 17:58:18 +00:00
LoopStrengthReduce.cpp	Use dyn_cast instead of isa && cast.	2013-03-24 09:25:47 +00:00
LoopUnrollPass.cpp	Switch CodeMetrics itself over to use TTI to determine if an instruction	2013-01-21 13:04:33 +00:00
LoopUnswitch.cpp	Switch CodeMetrics itself over to use TTI to determine if an instruction	2013-01-21 13:04:33 +00:00
LowerAtomic.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
Makefile
MemCpyOptimizer.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
Reassociate.cpp	Fix a XOR reassociation bug.	2013-04-27 18:02:12 +00:00
Reg2Mem.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
Scalar.cpp	This patch breaks up Wrap.h so that it does not have to include all of	2013-05-01 20:59:00 +00:00
ScalarReplAggregates.cpp	Fix a comment, PR15777.	2013-04-18 17:42:14 +00:00
SCCP.cpp	Remove dead code and whitespace.	2013-02-21 21:40:51 +00:00
SimplifyCFGPass.cpp	Make SimplifyCFG simply depend upon TargetTransformInfo and pass it	2013-01-07 03:53:25 +00:00
SimplifyLibCalls.cpp	simplify-libcalls: Removed unused variable	2013-03-21 02:44:07 +00:00
Sink.cpp	Move all of the header files which are involved in modelling the LLVM IR	2013-01-02 11:36:10 +00:00
SROA.cpp	SROA: Generate selects instead of shuffles when blending values because this is the cannonical form.	2013-05-01 19:53:30 +00:00
TailRecursionElimination.cpp	Begin fleshing out an interface in TTI for modelling the costs of	2013-01-22 11:26:02 +00:00