Add alignment support to linalg.buffer_alloc

This CL adds an integer attribute to linalg.buffer_alloc and lowering to LLVM.
The alignment is constrained to be a positive power of 2.

Lowering to LLVM produces the pattern:
```
%[[alloc:.*]] = llvm.call @malloc(%[[s]]) : (!llvm.i64) -> !llvm<"i8*">
%[[cast:.*]] = llvm.bitcast %[[alloc]] : !llvm<"i8*"> to !llvm.i64
%[[rem:.*]] = llvm.urem %[[cast]], %[[c16]] : !llvm.i64
%[[drem:.*]] = llvm.sub %[[c16]], %[[rem]] : !llvm.i64
%[[off:.*]] = llvm.urem %[[drem]], %[[c16]] : !llvm.i64
llvm.getelementptr %{{.*}}[%[[off]]] : (!llvm<"i8*">, !llvm.i64) -> !llvm<"i8*">
```

where `ptr` is aligned on `align` by computing the address
`ptr + (align - ptr % align) % align`.

To allow dealloc op to still be able to free memory, additional information is needed in
the buffer type. The buffer type is thus extended with an extra i8* for the base allocation address.

PiperOrigin-RevId: 264244455

0 files changed, 0 insertions, 0 deletions