[Lang] Revisit memory model #321
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This change cleans up some of the wording in the memory model and clearly defines the terms _byte_, _memory location_, _memory access_, and _memory operation_. These terms will be useful in writing the Classes chapter where the layout of objects needs to be defined.
Co-authored-by: Damyan Pepper <damyanp@microsoft.com>
Co-authored-by: Damyan Pepper <damyanp@microsoft.com>
Co-authored-by: Damyan Pepper <damyanp@microsoft.com>
specs/language/introduction.tex
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| must not alter memory at a location not contained in the set of memory locations it | ||
| is operating on\footnote{Two subtle notes here: (1) A bit-field's memory location | ||
| includes adjacent bit-fields, so reads and writes to bit-fields are expected to | ||
| read and write adjacent memory if they're within the same set of locations, (2) |
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To me the usage of 'same set of locations' is a bit ambiguous. After a few reads I assume it means the adjacent bit-fields. Maybe something like:
| read and write adjacent memory if they're within the same set of locations, (2) | |
| read and write adjacent memory if they're within the adjacent bitfields' memory locations, (2) |
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To me the usage of 'same set of locations' is a bit ambiguous. After a few reads I assume it means the adjacent bit-fields. Maybe something like:
Maybe a caveat is needed to specify the adjacent bitfields' memory locations, do not ALSO include their adjacent bitfields.
specs/language/introduction.tex
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| and a 128-bit \textit{minimum alignment}. | ||
| \end{note} | ||
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| \p A memory location in any space may overlap with another memory location in |
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Does this mean you have say a MAU of 4 bytes, but you can have a memory location that accesses at byte 0 and a different memory location that accesses at byte 2?
specs/language/introduction.tex
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| \p A memory location in any space may overlap with another memory location in | ||
| the same space. A memory location in thread or threadgroup memory may not | ||
| overlap with memory locations in any other memory spaces. It is implementation | ||
| defined if memory locations in other memory spaces alias with memory locations |
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This sentence here makes me wonder if I'm interpreting the first sentence in this paragraph correctly.
Edit: it didn't tag the line correctly. I mean line 314.
specs/language/introduction.tex
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| \SubSub{Constant Memory}{Intro.Memory.Spaces.Overlap} | ||
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| \p The \textbf{Thread} and \textbf{Thread Group} memory spaces may not overlap |
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Is this paragraph just stating part of what was said in the paragraph starting on line 311?
Nit: I was initially confused by the use of both 'memory location' and 'address'; I had just glazed over the fact that they are defined to be the same thing. It might be nice to use one or the other.
specs/language/introduction.tex
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| Operations that perform memory accesses are called \textit{memory operations}. A | ||
| memory operation may operate on one or more memory locations. A memory operation | ||
| must not alter memory at a location not contained in the set of memory locations it | ||
| is operating on\footnote{Two subtle notes here: (1) A bit-field's memory location |
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Defining the commonly understood term memory access granularity and specifying the access granularity to be a byte along with subsequent usage of the term may be a better option than using "bit-fields".
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Bit-fields are a specific language structure that has unique properties in the memory model because of their unique packing behavior.
This change cleans up some of the wording in the memory model and clearly defines the terms byte, memory location, memory access, and memory operation.
These terms will be useful in writing the Classes chapter where the layout of objects needs to be defined.