[Mlir-commits] [mlir] [mlir][doc] Improve Destination-passing-style documentation (PR #70283)

[Matthias Springer]

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@@ -101,26 +101,45 @@ bufferization strategy would be unacceptable for high-performance codegen. When
 choosing an already existing buffer, we must be careful not to accidentally
 overwrite data that is still needed later in the program.
 
-To simplify this problem, One-Shot Bufferize was designed for ops that are in
-*destination-passing style*. For every tensor result, such ops have a tensor
-operand, whose buffer could be utilized for storing the result of the op in the
-absence of other conflicts. We call such tensor operands the *destination*.
+To simplify this problem, One-Shot Bufferize was designed to take advantage of
+*destination-passing style*. This form exists in itself independently of
+bufferization and is tied to SSA semantics: many ops are “updating” part of
+their input SSA variable. For example the LLVM instruction
+[`insertelement`](https://llvm.org/docs/LangRef.html#insertelement-instruction)
+is inserting an element inside a vector. Since SSA values are immutable, the
+operation returns a copy of the input vector with the element inserted.
+Another example in MLIR is `linalg.generic`, which always has an extra `outs`
+operand which provides the initial values to update (for example when the
+operation is doing a reduction). 
+
+This input is referred to as "destination" in the following (quotes are
+important are this operand isn't modified in place but copied) and come into
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matthias-springer wrote:

grammar

https://github.com/llvm/llvm-project/pull/70283