================
@@ -3050,6 +3050,19 @@ as follows:
address space 0, this property only affects the default value to be used
when creating globals without additional contextual information (e.g. in
LLVM passes).
+``T<address space>``
+ Specifies the address space for a target's 'flat' address space. Note this
+ is not necessarily the same as addrspace 0, which LLVM sometimes refers to
+ as the generic address space. The flat address space is a generic address
+ space that can be used access multiple segments of memory with different
+ address spaces. Access of a memory location through a pointer with this
+ address space is expected to be legal but slower compared to the same
memory
+ location accessed through a pointer with a different address space. This is
+ for targets with different pointer representations which can be converted
+ with the addrspacecast instruction. If a pointer is converted to this
+ address space, optimizations should attempt to replace the access with the
+ source address space. The absence of this specification indicates the
target
+ does not have such a flat address space to optimize away.
----------------
nikic wrote:
>From this description, I don't really understand what flat address space means
>in terms of operational semantics. To put it differently: If you had to
>implement support for the flat address space concept in alive2, what would you
>do?
Some additional questions: Can there be more than one flat address space? If
you specify a flat address space, does that mean that all other address spaces
are not flat, and thus cannot alias with other address spaces? (If I understand
the concept correctly at all.)
https://github.com/llvm/llvm-project/pull/108786
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