llvm-6502/include/llvm/Transforms
Sanjay Patel d8214db086 fold: sqrt(x * x * y) -> fabs(x) * sqrt(y)
If a square root call has an FP multiplication argument that can be reassociated,
then we can hoist a repeated factor out of the square root call and into a fabs().

In the simplest case, this:

   y = sqrt(x * x);

becomes this:

   y = fabs(x);

This patch relies on an earlier optimization in instcombine or reassociate to put the
multiplication tree into a canonical form, so we don't have to search over
every permutation of the multiplication tree.

Because there are no IR-level FastMathFlags for intrinsics (PR21290), we have to
use function-level attributes to do this optimization. This needs to be fixed
for both the intrinsics and in the backend.

Differential Revision: http://reviews.llvm.org/D5787



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@219944 91177308-0d34-0410-b5e6-96231b3b80d8
2014-10-16 18:48:17 +00:00
..
IPO Add control of function merging to the PMBuilder. 2014-09-13 21:46:00 +00:00
Utils fold: sqrt(x * x * y) -> fabs(x) * sqrt(y) 2014-10-16 18:48:17 +00:00
Instrumentation.h [ASan] Completely remove sanitizer blacklist file from instrumentation pass. 2014-07-08 00:50:49 +00:00
IPO.h Move -verify-use-list-order into llvm-uselistorder 2014-07-25 17:13:03 +00:00
ObjCARC.h Reformat linefeeds. 2014-05-26 00:25:26 +00:00
Scalar.h [SimplifyCFG] threshold for folding branches with common destination 2014-09-30 22:23:38 +00:00
Vectorize.h