diff options
Diffstat (limited to 'gcc/fortran/dependency.c')
| -rw-r--r-- | gcc/fortran/dependency.c | 69 |
1 files changed, 65 insertions, 4 deletions
diff --git a/gcc/fortran/dependency.c b/gcc/fortran/dependency.c index c21a2e4..9dd4d9c 100644 --- a/gcc/fortran/dependency.c +++ b/gcc/fortran/dependency.c @@ -39,7 +39,8 @@ typedef enum { GFC_DEP_ERROR, GFC_DEP_EQUAL, /* Identical Ranges. */ - GFC_DEP_FORWARD, /* e.g., a(1:3), a(2:4). */ + GFC_DEP_FORWARD, /* e.g., a(1:3) = a(2:4). */ + GFC_DEP_BACKWARD, /* e.g. a(2:4) = a(1:3). */ GFC_DEP_OVERLAP, /* May overlap in some other way. */ GFC_DEP_NODEP /* Distinct ranges. */ } @@ -831,7 +832,7 @@ gfc_check_dependency (gfc_expr *expr1, gfc_expr *expr2, bool identical) /* Identical and disjoint ranges return 0, overlapping ranges return 1. */ if (expr1->ref && expr2->ref) - return gfc_dep_resolver (expr1->ref, expr2->ref); + return gfc_dep_resolver (expr1->ref, expr2->ref, NULL); return 1; @@ -1074,6 +1075,30 @@ gfc_check_section_vs_section (gfc_ref *lref, gfc_ref *rref, int n) return GFC_DEP_FORWARD; } + /* Check for backward dependencies: + Are the strides the same?. */ + if ((!l_stride && !r_stride) + || + (l_stride && r_stride + && gfc_dep_compare_expr (l_stride, r_stride) == 0)) + { + /* x:y vs. x+1:z. */ + if (l_dir == 1 && r_dir == 1 + && l_start && r_start + && gfc_dep_compare_expr (l_start, r_start) == 1 + && l_end && r_end + && gfc_dep_compare_expr (l_end, r_end) == 1) + return GFC_DEP_BACKWARD; + + /* x:y:-1 vs. x-1:z:-1. */ + if (l_dir == -1 && r_dir == -1 + && l_start && r_start + && gfc_dep_compare_expr (l_start, r_start) == -1 + && l_end && r_end + && gfc_dep_compare_expr (l_end, r_end) == -1) + return GFC_DEP_BACKWARD; + } + return GFC_DEP_OVERLAP; } @@ -1481,16 +1506,19 @@ ref_same_as_full_array (gfc_ref *full_ref, gfc_ref *ref) /* Finds if two array references are overlapping or not. Return value + 2 : array references are overlapping but reversal of one or + more dimensions will clear the dependency. 1 : array references are overlapping. 0 : array references are identical or not overlapping. */ int -gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref) +gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref, gfc_reverse *reverse) { int n; gfc_dependency fin_dep; gfc_dependency this_dep; + this_dep = GFC_DEP_ERROR; fin_dep = GFC_DEP_ERROR; /* Dependencies due to pointers should already have been identified. We only need to check for overlapping array references. */ @@ -1543,6 +1571,7 @@ gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref) if (lref->u.ar.dimen_type[n] == DIMEN_VECTOR || rref->u.ar.dimen_type[n] == DIMEN_VECTOR) return 1; + if (lref->u.ar.dimen_type[n] == DIMEN_RANGE && rref->u.ar.dimen_type[n] == DIMEN_RANGE) this_dep = gfc_check_section_vs_section (lref, rref, n); @@ -1563,6 +1592,38 @@ gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref) if (this_dep == GFC_DEP_NODEP) return 0; + /* Now deal with the loop reversal logic: This only works on + ranges and is activated by setting + reverse[n] == GFC_CAN_REVERSE + The ability to reverse or not is set by previous conditions + in this dimension. If reversal is not activated, the + value GFC_DEP_BACKWARD is reset to GFC_DEP_OVERLAP. */ + if (rref->u.ar.dimen_type[n] == DIMEN_RANGE + && lref->u.ar.dimen_type[n] == DIMEN_RANGE) + { + /* Set reverse if backward dependence and not inhibited. */ + if (reverse && reverse[n] != GFC_CANNOT_REVERSE) + reverse[n] = (this_dep == GFC_DEP_BACKWARD) ? + GFC_REVERSE_SET : reverse[n]; + + /* Inhibit loop reversal if dependence not compatible. */ + if (reverse && reverse[n] != GFC_REVERSE_NOT_SET + && this_dep != GFC_DEP_EQUAL + && this_dep != GFC_DEP_BACKWARD + && this_dep != GFC_DEP_NODEP) + { + reverse[n] = GFC_CANNOT_REVERSE; + if (this_dep != GFC_DEP_FORWARD) + this_dep = GFC_DEP_OVERLAP; + } + + /* If no intention of reversing or reversing is explicitly + inhibited, convert backward dependence to overlap. */ + if ((reverse == NULL && this_dep == GFC_DEP_BACKWARD) + || (reverse && reverse[n] == GFC_CANNOT_REVERSE)) + this_dep = GFC_DEP_OVERLAP; + } + /* Overlap codes are in order of priority. We only need to know the worst one.*/ if (this_dep > fin_dep) @@ -1578,7 +1639,7 @@ gfc_dep_resolver (gfc_ref *lref, gfc_ref *rref) /* Exactly matching and forward overlapping ranges don't cause a dependency. */ - if (fin_dep < GFC_DEP_OVERLAP) + if (fin_dep < GFC_DEP_BACKWARD) return 0; /* Keep checking. We only have a dependency if |