[flang-commits] [PATCH] D142770: [flang] Don't fold REPEAT() when the result would be too large
Peter Klausler via Phabricator via flang-commits
flang-commits at lists.llvm.org
Sun Jan 29 12:14:56 PST 2023
This revision was automatically updated to reflect the committed changes.
Closed by commit rG23f258cebbee: [flang] Don't fold REPEAT() when the result would be too large (authored by klausler).
Changed prior to commit:
https://reviews.llvm.org/D142770?vs=492830&id=493125#toc
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D142770/new/
https://reviews.llvm.org/D142770
Files:
flang/lib/Evaluate/character.h
flang/lib/Evaluate/fold-character.cpp
flang/test/Evaluate/errors01.f90
Index: flang/test/Evaluate/errors01.f90
===================================================================
--- flang/test/Evaluate/errors01.f90
+++ flang/test/Evaluate/errors01.f90
@@ -137,6 +137,10 @@
!CHERK: error: Must be a constant value
integer, parameter :: bad2 = storage_size(y)
end subroutine
+ subroutine s13
+ !CHECK: portability: Result of REPEAT() is too large to compute at compilation time (1.1259e+15 characters)
+ print *, repeat(repeat(' ', 2**20), 2**30)
+ end subroutine
subroutine warnings
real, parameter :: ok1 = scale(0.0, 99999) ! 0.0
real, parameter :: ok2 = scale(1.0, -99999) ! 0.0
Index: flang/lib/Evaluate/fold-character.cpp
===================================================================
--- flang/lib/Evaluate/fold-character.cpp
+++ flang/lib/Evaluate/fold-character.cpp
@@ -97,9 +97,16 @@
} else if (name == "repeat") { // not elemental
if (auto scalars{GetScalarConstantArguments<T, SubscriptInteger>(
context, funcRef.arguments())}) {
- return Expr<T>{Constant<T>{
- CharacterUtils<KIND>::REPEAT(std::get<Scalar<T>>(*scalars),
- std::get<Scalar<SubscriptInteger>>(*scalars).ToInt64())}};
+ auto str{std::get<Scalar<T>>(*scalars)};
+ auto n{std::get<Scalar<SubscriptInteger>>(*scalars).ToInt64()};
+ if (static_cast<double>(n) * str.size() >
+ (1 << 20)) { // sanity limit of 1MiB
+ context.messages().Say(
+ "Result of REPEAT() is too large to compute at compilation time (%g characters)"_port_en_US,
+ static_cast<double>(n) * str.size());
+ } else {
+ return Expr<T>{Constant<T>{CharacterUtils<KIND>::REPEAT(str, n)}};
+ }
}
} else if (name == "trim") { // not elemental
if (auto scalar{
Index: flang/lib/Evaluate/character.h
===================================================================
--- flang/lib/Evaluate/character.h
+++ flang/lib/Evaluate/character.h
@@ -106,6 +106,7 @@
static Character REPEAT(const Character &str, ConstantSubscript ncopies) {
Character result;
if (!str.empty()) {
+ result.reserve(ncopies * str.size());
while (ncopies-- > 0) {
result += str;
}
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