Chris Lattner 47c12a2771 Speed up the mem2reg transform for allocas which are only read/written in a single ... basic block. This is amazingly common in code generated by the C/C++ front-ends. This change makes it not have to insert ANY phi nodes, whereas before it would insert a ton of dead ones which DCE would have to clean up. Thus, this fix improves compile-time performance of these trivial allocas in two ways: 1. It doesn't have to do the walking and book-keeping for renaming 2. It does not insert dead phi nodes for them which would have to subsequently be cleaned up. On my favorite testcase from 252.eon, this special case handles 305 out of 356 promoted allocas in the function. It speeds up the mem2reg pass from 7.5256s to 1.2505s. It inserts 677 fewer dead PHI nodes, which speeds up a subsequent -dce pass from 18.7524s to 2.4806s. There are still 120 trivially dead PHI nodes being inserted for variables used in multiple basic blocks, but they are not handled by this patch. llvm-svn: 8881		2003-10-05 20:54:03 +00:00
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Hello	Initial checkin of the "Hello World" Pass.	2002-08-08 20:10:38 +00:00
Instrumentation	Use global *_iterator	2003-09-24 22:07:33 +00:00
IPO	Credits are now in top-level CREDITS.TXT	2003-09-22 21:57:15 +00:00
Scalar	Initial checkin of the LLVM->LLVM transform to support code generators which	2003-10-05 19:14:42 +00:00
Utils	Speed up the mem2reg transform for allocas which are only read/written in a single	2003-10-05 20:54:03 +00:00
ExprTypeConvert.cpp	Spell `necessary' correctly.	2003-08-18 14:43:39 +00:00
LevelRaise.cpp	Prototype for creator function got moved	2003-09-01 20:45:33 +00:00
Makefile	Convert DIRS to PARALLEL_DIRS. They can be built independently.	2002-09-29 11:52:14 +00:00
TransformInternals.cpp	avoid dividing by zero when dealing with zero sized types (like [0 x double])	2003-06-23 17:36:49 +00:00
TransformInternals.h	The word dependent' has no a'.	2003-08-21 22:14:26 +00:00