Sanjay Patel a46f06efe2 Use rsqrt (X86) to speed up reciprocal square root calcs ... This is a first step for generating SSE rsqrt instructions for reciprocal square root calcs when fast-math is allowed. For now, be conservative and only enable this for AMD btver2 where performance improves significantly - for example, 29% on llvm/projects/test-suite/SingleSource/Benchmarks/BenchmarkGame/n-body.c (if we convert the data type to single-precision float). This patch adds a two constant version of the Newton-Raphson refinement algorithm to DAGCombiner that can be selected by any target via a parameter returned by getRsqrtEstimate().. See PR20900 for more details: http://llvm.org/bugs/show_bug.cgi?id=20900 Differential Revision: http://reviews.llvm.org/D5658 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@220570 91177308-0d34-0410-b5e6-96231b3b80d8		2014-10-24 17:02:16 +00:00
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llvm	Use rsqrt (X86) to speed up reciprocal square root calcs	2014-10-24 17:02:16 +00:00
llvm-c	[LLVM-C] Add LLVMInstructionClone.	2014-10-17 01:02:34 +00:00