We already check hasNoNaNs and that x is finite and strictly positive.
That only leaves the following special cases (taken from the Linux man
page for pow):
If x is +1, the result is 1.0 (even if y is a NaN).
If the absolute value of x is less than 1, and y is negative infinity, the result is positive infinity.
If the absolute value of x is greater than 1, and y is negative infinity, the result is +0.
If the absolute value of x is less than 1, and y is positive infinity, the result is +0.
If the absolute value of x is greater than 1, and y is positive infinity, the result is positive infinity.
The first case is handled elsewhere, and this transformation preserves
all the others, so there is no need to limit it to hasNoInfs.
Differential Revision: https://reviews.llvm.org/D79409
We check that C is finite and strictly positive, but there's no need to
check that it's normal too. exp2 should be just as accurate on denormals
as pow is.
Differential Revision: https://reviews.llvm.org/D79413
I don't think there's any good reason not to do this transformation when
the pow has multiple uses.
Differential Revision: https://reviews.llvm.org/D79407
Summary:
Transform
pow(C,x)
To
exp2(log2(C)*x)
if C > 0, C != inf, C != NaN (and C is not power of 2, since we have some fold for such case already).
log(C) is folded by the compiler and exp2 is much faster to compute than pow.
Reviewers: spatel, efriedma, evandro
Reviewed By: evandro
Subscribers: lebedev.ri, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D64099
llvm-svn: 365637
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
Expand the simplification of `pow(exp{,2}(x), y)` to all FP types.
This improvement helps some benchmarks in SPEC CPU2000 and CPU2006, such as
252.eon, 447.dealII, 453.povray. Otherwise, no significant regressions on
x86-64 or A64.
Differential revision: https://reviews.llvm.org/D51195
llvm-svn: 340948
Fix the issue of duplicating the call to `exp{,2}()` when it's nested in
`pow()`, as exposed by rL340462.
Differential revision: https://reviews.llvm.org/D51194
llvm-svn: 340784
Prepatory patch before changing LibCallSimplifier to use the FMF.
Also, tighten the CHECK lines and give the tests more meaningful names.
Similar changes to:
http://reviews.llvm.org/rL257414
llvm-svn: 257481
This patch adds optional fast-math-flags (the same that apply to fmul/fadd/fsub/fdiv/frem/fcmp)
to call instructions in IR. Follow-up patches would use these flags in LibCallSimplifier, add
support to clang, and extend FMF to the DAG for calls.
Motivating example:
%y = fmul fast float %x, %x
%z = tail call float @sqrtf(float %y)
We'd like to be able to optimize sqrt(x*x) into fabs(x). We do this today using a function-wide
attribute for unsafe-math, but we really want to trigger on the instructions themselves:
%z = tail call fast float @sqrtf(float %y)
because in an LTO build it's possible that calls with fast semantics have been inlined into a
function with non-fast semantics.
The code changes and tests are based on the recent commits that added "notail":
http://reviews.llvm.org/rL252368
and added FMF to fcmp:
http://reviews.llvm.org/rL241901
Differential Revision: http://reviews.llvm.org/D14707
llvm-svn: 255555
Jay Foad