tree-optimization/100981 - fix SLP patterns involving reductions

The following fixes the SLP FMA patterns to preserve reduction
info and the reduction vectorization to consider internal function
call defs for the reduction stmt.

2021-06-09  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/100981
gcc/
	* tree-vect-loop.c (vect_create_epilog_for_reduction): Use
	gimple_get_lhs to also handle calls.
	* tree-vect-slp-patterns.c (complex_pattern::build): Transfer
	reduction info.

gcc/testsuite/
	* gfortran.dg/vect/pr100981-1.f90: New testcase.

libgomp/
	* testsuite/libgomp.fortran/pr100981-2.f90: New testcase.

1 files changed, 31 insertions, 0 deletions

diff --git a/libgomp/testsuite/libgomp.fortran/pr100981-2.f90 b/libgomp/testsuite/libgomp.fortran/pr100981-2.f90
new file mode 100644
index 0000000..12836d4
--- /dev/null
+++ b/libgomp/testsuite/libgomp.fortran/pr100981-2.f90
@@ -0,0 +1,31 @@
+! { dg-do run }
+! { dg-additional-options "-O3 -ftree-parallelize-loops=2 -fno-signed-zeros -fno-trapping-math" }
+
+complex function cdcdot(n, cx)
+  implicit none
+
+  integer :: n, i, kx
+  complex :: cx(*)
+  double precision :: dsdotr, dsdoti, dt1, dt3
+
+  kx = 1
+  do i = 1, n
+     dt1 = real(cx(kx))
+     dt3 = aimag(cx(kx))
+     dsdotr = dsdotr + dt1 * 2 - dt3 * 2
+     dsdoti = dsdoti + dt1 * 2 + dt3 * 2
+     kx = kx + 1
+  end do
+  cdcdot = cmplx(real(dsdotr), real(dsdoti))
+  return
+end function cdcdot
+program test
+  implicit none
+  complex :: cx(100), ct, cdcdot
+  integer :: i
+  do i = 1, 100
+    cx(i) = cmplx(2*i, i)
+  end do
+  ct = cdcdot (100, cx)
+  if (ct.ne.cmplx(10100.0000,30300.0000)) call abort
+end