Summary:
When X = 0 and Y = inf, the original code produces inf, but the transformed
code produces nan. So this transform (and its relatives) should only be
used when the no-infs-fp-math flag is explicitly enabled.
Also disable the transform using fmad (intermediate rounding) when unsafe-math
is not enabled, since it can reduce the precision of the result; consider this
example with binary floating point numbers with two bits of mantissa:
x = 1.01
y = 111
x * (y + 1) = 1.01 * 1000 = 1010 (this is the exact result; no rounding occurs at any step)
x * y + x = 1000.11 + 1.01 =r 1000 + 1.01 = 1001.01 =r 1000 (with rounding towards zero)
The example relies on rounding towards zero at least in the second step.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98578
Reviewers: RKSimon, tstellarAMD, spatel, arsenm
Subscribers: wdng, llvm-commits
Differential Revision: https://reviews.llvm.org/D26602
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288506 91177308-0d34-0410-b5e6-96231b3b80d8
Ideally we would use VEX encoded moves instead of EVEX if the high 16 registers aren't referenced, but this a good first step.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@275763 91177308-0d34-0410-b5e6-96231b3b80d8
We currently output FMA instructions on targets which support both FMA4 + FMA (i.e. later Bulldozer CPUS bdver2/bdver3/bdver4).
This patch flips this so FMA4 is preferred; this is for several reasons:
1 - FMA4 is non-destructive reducing the need for mov instructions.
2 - Its more straighforward to commute and fold inputs (although the recent work on FMA has reduced this difference).
3 - All supported targets have FMA4 performance equal or better to FMA - Piledriver (bdver2) in particular has half the throughput when executing FMA instructions.
Its looks like no future AMD processor lines will support FMA4 after the Bulldozer series so we're not causing problems for later CPUs.
Differential Revision: http://reviews.llvm.org/D14997
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254339 91177308-0d34-0410-b5e6-96231b3b80d8
Added FMADD/FMSUB/FNMADD/FNMSUB tests for all types
Added load folding tests for 512-bit vectors
NOTE: Many of the AVX512 FMA instructions don't yet commute/fold correctly
As discussed on D14909
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254232 91177308-0d34-0410-b5e6-96231b3b80d8
X86 needs to use its own FMA opcodes, preventing the standard FNEG(FMA) pattern table recognition method used by other platforms. This patch adds support for lowering FNEG(FMA(X,Y,Z)) into a single suitably negated FMA instruction.
Fix for PR24364
Differential Revision: http://reviews.llvm.org/D14906
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@254016 91177308-0d34-0410-b5e6-96231b3b80d8
This patch adds support for combining patterns such as (FMUL(FADD(1.0, x), y)) and (FMUL(FSUB(x, 1.0), y)) to their FMA equivalents.
This is useful in particular for linear interpolation cases such as (FADD(FMUL(x, t), FMUL(y, FSUB(1.0, t))))
Differential Revision: http://reviews.llvm.org/D13003
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@248210 91177308-0d34-0410-b5e6-96231b3b80d8
Essentially the same as the GEP change in r230786.
A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)
import fileinput
import sys
import re
pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")
for line in sys.stdin:
sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))
Reviewers: rafael, dexonsmith, grosser
Differential Revision: http://reviews.llvm.org/D7649
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230794 91177308-0d34-0410-b5e6-96231b3b80d8
corresponding changes to existing tests for darwin triple to ensure that
same pattern is tested for bdver2 target.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162655 91177308-0d34-0410-b5e6-96231b3b80d8
Dinar Temirbulatov