35 lines
1.3 KiB
Markdown
35 lines
1.3 KiB
Markdown
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<!--===- docs/Extensions.md
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Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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See https://llvm.org/LICENSE.txt for license information.
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SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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-->
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# OpenACC in Flang
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```{contents}
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---
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local:
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---
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```
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## Intentional deviation from the specification
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* The end directive for combined construct can omit the `loop` keyword.
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* An `!$acc routine` with no parallelism clause is treated as if the `seq`
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clause was present.
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* `!$acc end loop` does not trigger a parsing error and is just ignored.
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* The restriction on `!$acc data` required clauses is emitted as a portability
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warning instead of an error as other compiler accepts it.
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* The `if` clause accepts scalar integer expression in addition to scalar
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logical expression.
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* `!$acc routine` directive can be placed at the top level.
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* `!$acc cache` directive accepts scalar variable.
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## Remarks about incompatibilities with other implementations
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* Array element references in the data clauses are equivalent to array sections
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consisting of this single element, i.e. `copyin(a(n))` is equivalent to
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`copyin(a(n:n))`. Some other implementations have treated it as
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`copyin(a(:n))`, which does not correspond to OpenACC spec – Flang does not
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support this interpretation of an array element reference.
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