openmp: Map holds clause to IFN_ASSUME for Fortran

Same as r13-3107-g847f5addc4d07a2f3b95f5daa50ab4a64dfd957d did for C/C++.
Convert '!$omp assume holds(cond)' to IFN_ASSUME (cond).

gcc/fortran/
	* trans-openmp.cc (gfc_trans_omp_assume): New.
	(gfc_trans_omp_directive): Call it.

gcc/testsuite/
	* gfortran.dg/gomp/assume-3.f90: New test.
	* gfortran.dg/gomp/assume-4.f90: New test.

2 files changed, 96 insertions, 0 deletions

diff --git a/gcc/testsuite/gfortran.dg/gomp/assume-3.f90 b/gcc/testsuite/gfortran.dg/gomp/assume-3.f90
new file mode 100644
index 0000000..e5deace
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/assume-3.f90
@@ -0,0 +1,46 @@
+! { dg-do compile }
+! { dg-options "-fopenmp -O2 -fdump-tree-optimized -fdump-tree-original" }
+
+! { dg-final { scan-tree-dump-times ".ASSUME \\(x == 42\\);" 1 "original" } }
+! { dg-final { scan-tree-dump-times ".ASSUME \\(x <= 41\\);" 1 "original" } }
+! { dg-final { scan-tree-dump-times ".ASSUME \\(y <= 6\\);" 1 "original" } }
+! { dg-final { scan-tree-dump-times ".ASSUME \\(y > 5\\);" 1 "original" } }
+
+! { dg-final { scan-tree-dump-times "return 42;" 3 "optimized" } }
+! { dg-final { scan-tree-dump-not "return -1;" "optimized" } }
+
+integer function foo (x)
+  implicit none
+  integer, value :: x
+  integer :: y
+  !$omp assume holds (x == 42)
+    y = x;
+  !$omp end assume
+  foo = y
+end
+
+integer function bar (x)
+  implicit none
+  integer, value :: x
+  !$omp assume holds (x < 42)
+  block
+  end block
+  if (x == 42) then
+    bar = -1
+    return
+  end if
+  bar = 42
+end
+
+integer function foobar (y)
+  implicit none
+  integer, value :: y
+  !$omp assume holds(y > 5) holds (y < 7)
+  block
+    if (y == 6) then
+      foobar = 42
+      return
+    end if
+  end block
+  foobar = -1
+end
diff --git a/gcc/testsuite/gfortran.dg/gomp/assume-4.f90 b/gcc/testsuite/gfortran.dg/gomp/assume-4.f90
new file mode 100644
index 0000000..45857c4
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/assume-4.f90
@@ -0,0 +1,50 @@
+! { dg-do compile }
+! { dg-options "-fopenmp -O2 -fdump-tree-original -fdump-tree-optimized" }
+! { dg-final { scan-tree-dump-times ".ASSUME \\(i_lower_bound \\(\\) < i\\);" 1 "original" } }
+! { dg-final { scan-tree-dump-times ".ASSUME \\(TARGET_EXPR <D.\[0-9\]+, D.\[0-9\]+ = j_upper_bound \\(\\);" 1 "original" } }
+! { dg-final { scan-tree-dump-times "__builtin_free" 1 "original" } }
+
+! { dg-final { scan-tree-dump-not "i_lower_bound" "optimized" } }
+! { dg-final { scan-tree-dump-not "j_upper_bound" "optimized" } }
+! { dg-final { scan-tree-dump-not "__builtin_free" "optimized" } }
+
+! Note: Currently, the assumption does not help with optimization in either variant.
+
+
+integer function f(i)
+  implicit none
+  integer, value :: i
+
+  !$omp assume holds(i > i_lower_bound ())
+  block
+    if (i > 4) then
+      f = 42
+    else
+      f = -1
+    end if
+  end block
+contains
+  function i_lower_bound ()
+    integer :: i_lower_bound
+    i_lower_bound = 5
+  end function
+end
+
+integer function g(j)
+  implicit none
+  integer, value :: j
+
+  !$omp assume holds(j < j_upper_bound ())
+  block
+    if (j < 10) then
+      g = 42
+    else
+      g = -1
+    end if
+  end block
+contains
+  function j_upper_bound ()
+    integer, allocatable :: j_upper_bound
+    j_upper_bound = 10
+  end function
+end