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| author | Sanjay Patel <spatel@rotateright.com> | 2014-10-09 21:26:35 +0000 |
|---|---|---|
| committer | Sanjay Patel <spatel@rotateright.com> | 2014-10-09 21:26:35 +0000 |
| commit | 3d497cd778261818eb76b5ad97f7f751cfebfcbb (patch) | |
| tree | bfe0a173e16fda4bc5c4271a572710d6e44f6c38 /llvm/test/Feature/alias2.ll | |
| parent | 6d28da10e5d1ff6567871dd5929ec84b762fe208 (diff) | |
| download | bcm5719-llvm-3d497cd778261818eb76b5ad97f7f751cfebfcbb.tar.gz bcm5719-llvm-3d497cd778261818eb76b5ad97f7f751cfebfcbb.zip | |
Improve sqrt estimate algorithm (fast-math)
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
llvm-svn: 219445
Diffstat (limited to 'llvm/test/Feature/alias2.ll')
0 files changed, 0 insertions, 0 deletions
