[flang-commits] [flang] [flang] Better IS_CONTIGUOUS folding for substrings (PR #115970)
Peter Klausler via flang-commits
flang-commits at lists.llvm.org
Tue Nov 12 16:44:55 PST 2024
https://github.com/klausler created https://github.com/llvm/llvm-project/pull/115970
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.
>From 4490f2d446b7a4ca216662614ec22b84aca67308 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 | 34 ++++++++++++++++++++++++-
flang/test/Evaluate/folding09.f90 | 7 +++++
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, 48 insertions(+), 9 deletions(-)
diff --git a/flang/lib/Evaluate/check-expression.cpp b/flang/lib/Evaluate/check-expression.cpp
index 38794a2d8aacc7..efc08763aa9ad6 100644
--- a/flang/lib/Evaluate/check-expression.cpp
+++ b/flang/lib/Evaluate/check-expression.cpp
@@ -908,7 +908,39 @@ 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 {
+ auto base{x.GetBaseObject()};
+ if (x.Rank() == 0) {
+ return true; // scalar substring always contiguous
+ }
+ Result result{(*this)(base)};
+ if (!result || *result) {
+ if (auto lower{ToInt64(Fold(context_, x.lower()))}) {
+ auto upperExpr{x.upper()};
+ auto lenExpr{base.LEN()};
+ if (!upperExpr) {
+ upperExpr = lenExpr;
+ }
+ if (!upperExpr) {
+ return std::nullopt; // could be empty substrings
+ } else if (auto upper{ToInt64(Fold(context_, std::move(*upperExpr)))}) {
+ if (*upper < *lower) {
+ return true; // empty substrings: vacuously contiguous
+ } else if (*lower > 1) {
+ return false; // lower > 1
+ } else if (lenExpr) {
+ if (auto lenVal{ToInt64(Fold(context_, std::move(*lenExpr)))};
+ lenVal && *lenVal != *upper) {
+ return false; // upper < length
+ }
+ }
+ }
+ } else {
+ return std::nullopt; // lower bound not known
+ }
+ }
+ return result;
+ }
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..b9c00710a086ca 100644
--- a/flang/test/Evaluate/folding09.f90
+++ b/flang/test/Evaluate/folding09.f90
@@ -21,6 +21,7 @@ subroutine test(arr1, arr2, arr3, mat, alloc)
real, intent(in), contiguous :: arr3(:)
real, allocatable :: alloc(:)
real :: scalar
+ character(5) charr(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 +36,12 @@ 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
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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