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a4554c2897
This patch changes the fast-math implementation for calculating sqrt(x) from: y = 1 / (1 / sqrt(x)) to: y = x * (1 / sqrt(x)) This has 2 benefits: less code / faster code and one less estimate instruction that may lose precision. The only target that will be affected (until http://reviews.llvm.org/D5658 is approved) is PPC. The difference in codegen for PPC is 2 less flops for a single-precision sqrtf or vector sqrtf and 4 less flops for a double-precision sqrt. We also eliminate a constant load and extra register usage. Differential Revision: http://reviews.llvm.org/D5682 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219445 91177308-0d34-0410-b5e6-96231b3b80d8