Hal Finkel b19dd2bcaf Revert r185257 (InstCombine: Be more agressive optimizing 'udiv' instrs with 'select' denoms) ... I'm reverting this commit because: 1. As discussed during review, it needs to be rewritten (to avoid creating and then deleting instructions). 2. This is causing optimizer crashes. Specifically, I'm seeing things like this: While deleting: i1 % Use still stuck around after Def is destroyed: <badref> = select i1 <badref>, i32 0, i32 1 opt: /src/llvm-trunk/lib/IR/Value.cpp:79: virtual llvm::Value::~Value(): Assertion `use_empty() && "Uses remain when a value is destroyed!"' failed. I'd guess that these will go away once we're no longer creating/deleting instructions here, but just in case, I'm adding a regression test. Because the code is bring rewritten, I've just XFAIL'd the original regression test. Original commit message: InstCombine: Be more agressive optimizing 'udiv' instrs with 'select' denoms Real world code sometimes has the denominator of a 'udiv' be a 'select'. LLVM can handle such cases but only when the 'select' operands are symmetric in structure (both select operands are a constant power of two or a left shift, etc.). This falls apart if we are dealt a 'udiv' where the code is not symetric or if the select operands lead us to more select instructions. Instead, we should treat the LHS and each select operand as a distinct divide operation and try to optimize them independently. If we can to simplify each operation, then we can replace the 'udiv' with, say, a 'lshr' that has a new select with a bunch of new operands for the select. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185415 91177308-0d34-0410-b5e6-96231b3b80d8		2013-07-02 05:21:11 +00:00
..
CMakeLists.txt
InstCombine.h
InstCombineAddSub.cpp
InstCombineAndOrXor.cpp
InstCombineCalls.cpp	Fix using arg_end() - arg_begin() instead of arg_size()	2013-06-28 00:25:40 +00:00
InstCombineCasts.cpp
InstCombineCompares.cpp	InstCombine: FoldGEPICmp shouldn't change sign of base pointer comparison	2013-06-29 10:28:04 +00:00
InstCombineLoadStoreAlloca.cpp
InstCombineMulDivRem.cpp	Revert r185257 (InstCombine: Be more agressive optimizing 'udiv' instrs with 'select' denoms)	2013-07-02 05:21:11 +00:00
InstCombinePHI.cpp
InstCombineSelect.cpp	InstCombine: Also turn selects fed by an and into arithmetic when the types don't match.	2013-06-29 21:17:04 +00:00
InstCombineShifts.cpp
InstCombineSimplifyDemanded.cpp
InstCombineVectorOps.cpp
InstCombineWorklist.h
InstructionCombining.cpp
LLVMBuild.txt
Makefile