[flang-commits] [flang] [flang] Better IS_CONTIGUOUS folding for substrings (PR #115970)
Peter Klausler via flang-commits
flang-commits at lists.llvm.org
Thu Nov 14 12:37:57 PST 2024
https://github.com/klausler updated https://github.com/llvm/llvm-project/pull/115970
>From 7e77e64cdc9072f0980b5efaf44a4b93bae7f2ef Mon Sep 17 00:00:00 2001
From: Peter Klausler <pklausler at nvidia.com>
Date: Tue, 12 Nov 2024 16:40:49 -0800
Subject: [PATCH] [flang] Better IS_CONTIGUOUS folding for substrings
At present, the compiler doesn't analyze substring references
for contiguity. But there are cases where substrings can be known
to be contiguous (scalar base, empty substring, or complete substring)
or can be known to be discontiguous, and references to the intrinsic
function IS_CONTIGUOUS in those cases may appear in constant expressions.
Fixes https://github.com/llvm/llvm-project/issues/115675.
---
flang/lib/Evaluate/check-expression.cpp | 53 ++++++++++++++++++++++++-
flang/test/Evaluate/folding09.f90 | 19 ++++++++-
flang/test/Lower/HLFIR/maxloc.f90 | 4 +-
flang/test/Lower/HLFIR/maxval.f90 | 4 +-
flang/test/Lower/HLFIR/minloc.f90 | 4 +-
flang/test/Lower/HLFIR/minval.f90 | 4 +-
6 files changed, 77 insertions(+), 11 deletions(-)
diff --git a/flang/lib/Evaluate/check-expression.cpp b/flang/lib/Evaluate/check-expression.cpp
index 38794a2d8aacc7..998378c44cdf41 100644
--- a/flang/lib/Evaluate/check-expression.cpp
+++ b/flang/lib/Evaluate/check-expression.cpp
@@ -908,7 +908,58 @@ class IsContiguousHelper
Result operator()(const ComplexPart &x) const {
return x.complex().Rank() == 0;
}
- Result operator()(const Substring &) const { return std::nullopt; }
+ Result operator()(const Substring &x) const {
+ if (x.Rank() == 0) {
+ return true; // scalar substring always contiguous
+ }
+ // Substrings with rank must have DataRefs as their parents
+ const DataRef &parentDataRef{DEREF(x.GetParentIf<DataRef>())};
+ std::optional<std::int64_t> len;
+ if (auto lenExpr{parentDataRef.LEN()}) {
+ len = ToInt64(Fold(context_, std::move(*lenExpr)));
+ if (len) {
+ if (*len <= 0) {
+ return true; // empty substrings
+ } else if (*len == 1) {
+ // Substrings can't be incomplete; is base array contiguous?
+ return (*this)(parentDataRef);
+ }
+ }
+ }
+ std::optional<std::int64_t> upper;
+ bool upperIsLen{false};
+ if (auto upperExpr{x.upper()}) {
+ upper = ToInt64(Fold(context_, common::Clone(*upperExpr)));
+ if (upper) {
+ if (*upper < 1) {
+ return true; // substring(n:0) empty
+ }
+ upperIsLen = len && *upper >= *len;
+ } else if (const auto *inquiry{
+ UnwrapConvertedExpr<DescriptorInquiry>(*upperExpr)};
+ inquiry && inquiry->field() == DescriptorInquiry::Field::Len) {
+ upperIsLen =
+ &parentDataRef.GetLastSymbol() == &inquiry->base().GetLastSymbol();
+ }
+ } else {
+ upperIsLen = true; // substring(n:)
+ }
+ if (auto lower{ToInt64(Fold(context_, x.lower()))}) {
+ if (*lower == 1 && upperIsLen) {
+ // known complete substring; is base contiguous?
+ return (*this)(parentDataRef);
+ } else if (upper) {
+ if (*upper < *lower) {
+ return true; // empty substring(3:2)
+ } else if (*lower > 1) {
+ return false; // known incomplete substring
+ } else if (len && *upper < *len) {
+ return false; // known incomplete substring
+ }
+ }
+ }
+ return std::nullopt; // contiguity not known
+ }
Result operator()(const ProcedureRef &x) const {
if (auto chars{characteristics::Procedure::Characterize(
diff --git a/flang/test/Evaluate/folding09.f90 b/flang/test/Evaluate/folding09.f90
index 863b5e873a1e5b..534ff1a89a174d 100644
--- a/flang/test/Evaluate/folding09.f90
+++ b/flang/test/Evaluate/folding09.f90
@@ -5,7 +5,7 @@ module m
real, target :: hosted(2)
integer, parameter :: cst(2,2) = reshape([1, 2, 3, 4], shape(cst))
integer, parameter :: empty_cst(2,0) = reshape([1], shape(empty_cst))
- integer :: n
+ integer :: n, m
logical, parameter :: test_param1 = is_contiguous(cst(:,1))
logical, parameter :: test_param2 = is_contiguous(cst(1,:))
logical, parameter :: test_param3 = is_contiguous(cst(:,n))
@@ -16,11 +16,15 @@ function f()
real, pointer, contiguous :: f(:)
f => hosted
end function
- subroutine test(arr1, arr2, arr3, mat, alloc)
+ subroutine test(arr1, arr2, arr3, mat, alloc, alch)
real, intent(in) :: arr1(:), arr2(10), mat(10, 10)
real, intent(in), contiguous :: arr3(:)
real, allocatable :: alloc(:)
real :: scalar
+ character(5) charr(5)
+ character(1) char1(5)
+ character(0) char0(5)
+ character(*) alch(5)
integer(kind=merge(1,-1, is_contiguous(0))) t01
integer(kind=merge(1,-1, is_contiguous(scalar))) t02
integer(kind=merge(1,-1, is_contiguous(scalar + scalar))) t03
@@ -35,6 +39,17 @@ subroutine test(arr1, arr2, arr3, mat, alloc)
integer(kind=merge(1,-1, .not. is_contiguous(arr3(1:10:2)))) t12
integer(kind=merge(1,-1, is_contiguous(f()))) t13
integer(kind=merge(1,-1, is_contiguous(alloc))) t14
+ integer(kind=merge(1,-1, is_contiguous(charr(:)(:)))) t15
+ integer(kind=merge(1,-1, is_contiguous(charr(1)(2:3)))) t16
+ integer(kind=merge(1,-1, is_contiguous(charr(:)(1:)))) t17
+ integer(kind=merge(1,-1, is_contiguous(charr(:)(3:2)))) t18
+ integer(kind=merge(1,-1, is_contiguous(charr(:)(1:5)))) t19
+ integer(kind=merge(1,-1, .not. is_contiguous(charr(:)(1:4)))) t20
+ integer(kind=merge(1,-1, is_contiguous(char1(:)(n:m)))) t21
+ integer(kind=merge(1,-1, .not. is_contiguous(char1(1:5:2)(n:m)))) t22
+ integer(kind=merge(1,-1, is_contiguous(char0(:)(n:m)))) t23
+ integer(kind=merge(1,-1, is_contiguous(char0(1:5:2)(n:m)))) t24
+ integer(kind=merge(1,-1, is_contiguous(alch(:)(:)))) t25
associate (x => arr2)
block
integer(kind=merge(1,-1,is_contiguous(x))) n
diff --git a/flang/test/Lower/HLFIR/maxloc.f90 b/flang/test/Lower/HLFIR/maxloc.f90
index 166a1b9db1724e..539affad2d7df1 100644
--- a/flang/test/Lower/HLFIR/maxloc.f90
+++ b/flang/test/Lower/HLFIR/maxloc.f90
@@ -341,8 +341,8 @@ end subroutine test_unknown_char_len_result
! CHECK-DAG: %[[C1_7:.*]] = arith.constant 1 : index
! CHECK-DAG: %[[C3_8:.*]] = arith.constant 3 : index
! CHECK-DAG: %[[C3_9:.*]] = arith.constant 3 : index
-! CHECK-DAG: %[[ARRAY_BOX:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]]
-! CHECK: %[[EXPR:.*]] = hlfir.maxloc %[[ARRAY_BOX]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<2xi32>
+! CHECK-DAG: %[[ARRAY_REF:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]] : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>, index, index, index, index, index, index, index, index, !fir.shape<2>, index) -> !fir.ref<!fir.array<3x3x!fir.char<1,3>>>
+! CHECK: %[[EXPR:.*]] = hlfir.maxloc %[[ARRAY_REF]] {fastmath = #arith.fastmath<contract>} : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<2xi32>
! CHECK-NEXT: hlfir.assign %[[EXPR]] to %[[RES]]#0 : !hlfir.expr<2xi32>, !fir.ref<!fir.array<2xi32>>
! CHECK-NEXT: hlfir.destroy %[[EXPR]]
! CHECK-NEXT: return
diff --git a/flang/test/Lower/HLFIR/maxval.f90 b/flang/test/Lower/HLFIR/maxval.f90
index 5adad286a77d28..32e1a80417a27b 100644
--- a/flang/test/Lower/HLFIR/maxval.f90
+++ b/flang/test/Lower/HLFIR/maxval.f90
@@ -254,8 +254,8 @@ end subroutine test_unknown_char_len_result
! CHECK-DAG: %[[C1_7:.*]] = arith.constant 1 : index
! CHECK-DAG: %[[C3_8:.*]] = arith.constant 3 : index
! CHECK-DAG: %[[C3_9:.*]] = arith.constant 3 : index
-! CHECK-DAG: %[[ARRAY_BOX:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]]
-! CHECK: %[[EXPR:.*]] = hlfir.maxval %[[ARRAY_BOX]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<!fir.char<1,3>>
+! CHECK-DAG: %[[ARRAY_REF:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]] : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>, index, index, index, index, index, index, index, index, !fir.shape<2>, index) -> !fir.ref<!fir.array<3x3x!fir.char<1,3>>>
+! CHECK: %[[EXPR:.*]] = hlfir.maxval %[[ARRAY_REF]] {fastmath = #arith.fastmath<contract>} : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<!fir.char<1,3>>
! CHECK-NEXT: hlfir.assign %[[EXPR]] to %[[RES]]#0 : !hlfir.expr<!fir.char<1,3>>, !fir.ref<!fir.char<1,3>>
! CHECK-NEXT: hlfir.destroy %[[EXPR]]
! CHECK-NEXT: return
diff --git a/flang/test/Lower/HLFIR/minloc.f90 b/flang/test/Lower/HLFIR/minloc.f90
index f835cf54b2a73e..ce149ffcfb54fd 100644
--- a/flang/test/Lower/HLFIR/minloc.f90
+++ b/flang/test/Lower/HLFIR/minloc.f90
@@ -341,8 +341,8 @@ end subroutine test_unknown_char_len_result
! CHECK-DAG: %[[C1_7:.*]] = arith.constant 1 : index
! CHECK-DAG: %[[C3_8:.*]] = arith.constant 3 : index
! CHECK-DAG: %[[C3_9:.*]] = arith.constant 3 : index
-! CHECK-DAG: %[[ARRAY_BOX:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]]
-! CHECK: %[[EXPR:.*]] = hlfir.minloc %[[ARRAY_BOX]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<2xi32>
+! CHECK-DAG: %[[ARRAY_REF:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]] : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>, index, index, index, index, index, index, index, index, !fir.shape<2>, index) -> !fir.ref<!fir.array<3x3x!fir.char<1,3>>>
+! CHECK: %[[EXPR:.*]] = hlfir.minloc %[[ARRAY_REF]] {fastmath = #arith.fastmath<contract>} : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<2xi32>
! CHECK-NEXT: hlfir.assign %[[EXPR]] to %[[RES]]#0 : !hlfir.expr<2xi32>, !fir.ref<!fir.array<2xi32>>
! CHECK-NEXT: hlfir.destroy %[[EXPR]]
! CHECK-NEXT: return
diff --git a/flang/test/Lower/HLFIR/minval.f90 b/flang/test/Lower/HLFIR/minval.f90
index 01b0ce77e2d30e..2ac9aba850b6f4 100644
--- a/flang/test/Lower/HLFIR/minval.f90
+++ b/flang/test/Lower/HLFIR/minval.f90
@@ -254,8 +254,8 @@ end subroutine test_unknown_char_len_result
! CHECK-DAG: %[[C1_7:.*]] = arith.constant 1 : index
! CHECK-DAG: %[[C3_8:.*]] = arith.constant 3 : index
! CHECK-DAG: %[[C3_9:.*]] = arith.constant 3 : index
-! CHECK-DAG: %[[ARRAY_BOX:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]]
-! CHECK: %[[EXPR:.*]] = hlfir.minval %[[ARRAY_BOX]] {fastmath = #arith.fastmath<contract>} : (!fir.box<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<!fir.char<1,3>>
+! CHECK-DAG: %[[ARRAY_REF:.*]] = hlfir.designate %[[ARRAY]]#0 (%[[C1]]:%[[C3_0]]:%[[C1_3]], %[[C1]]:%[[C3_1]]:%[[C1_5]]) substr %[[C1_7]], %[[C3_8]] shape %[[SHAPE]] typeparams %[[C3_9]] : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>, index, index, index, index, index, index, index, index, !fir.shape<2>, index) -> !fir.ref<!fir.array<3x3x!fir.char<1,3>>>
+! CHECK: %[[EXPR:.*]] = hlfir.minval %[[ARRAY_REF]] {fastmath = #arith.fastmath<contract>} : (!fir.ref<!fir.array<3x3x!fir.char<1,3>>>) -> !hlfir.expr<!fir.char<1,3>>
! CHECK-NEXT: hlfir.assign %[[EXPR]] to %[[RES]]#0 : !hlfir.expr<!fir.char<1,3>>, !fir.ref<!fir.char<1,3>>
! CHECK-NEXT: hlfir.destroy %[[EXPR]]
! CHECK-NEXT: return
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