[all-commits] [llvm/llvm-project] e3aa00: [mlir][ptr] Add `ptr.ptr_diff` operation (#157354)

[Fabian Mora via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: e3aa00e517e58583f96ca62e2c654d9ce6dec060
      https://github.com/llvm/llvm-project/commit/e3aa00e517e58583f96ca62e2c654d9ce6dec060
  Author: Fabian Mora <fmora.dev at gmail.com>
  Date:   2025-09-24 (Wed, 24 Sep 2025)

  Changed paths:
    M mlir/include/mlir/Dialect/Ptr/IR/PtrEnums.td
    M mlir/include/mlir/Dialect/Ptr/IR/PtrOps.td
    M mlir/lib/Dialect/Ptr/IR/PtrDialect.cpp
    M mlir/lib/Target/LLVMIR/Dialect/Ptr/PtrToLLVMIRTranslation.cpp
    M mlir/test/Dialect/Ptr/invalid.mlir
    M mlir/test/Dialect/Ptr/ops.mlir
    M mlir/test/Target/LLVMIR/ptr.mlir

  Log Message:
  -----------
  [mlir][ptr] Add `ptr.ptr_diff` operation (#157354)

Thi patch introduces the `ptr.ptr_diff` operation for computing pointer
differences. The semantics of the operation are given by:
```
The `ptr_diff` operation computes the difference between two pointers,
returning an integer or index value representing the number of bytes
between them.

The operation supports both scalar and shaped types with value semantics:
- When both operands are scalar: produces a single difference value
- When both are shaped: performs element-wise subtraction,
  shapes must be the same

The operation also supports the following flags:
- `none`: No flags are set.
- `nuw`: No Unsigned Wrap, if the subtraction causes an unsigned overflow,
  the result is a poison value.
- `nsw`: No Signed Wrap, if the subtraction causes a signed overflow, the
  result is a poison value.

NOTE: The pointer difference is calculated using an integer type specified
by the data layout. The final result will be sign-extended or truncated to
fit the result type as necessary.
```

This patch also adds translation to LLVM IR hooks for the `ptr_diff` op.
This translation uses the `ptrtoaddr` builder to compute only index bits
difference.

Example:
```mlir
llvm.func @ptr_diff_vector_i32(%ptrs1: vector<8x!ptr.ptr<#llvm.address_space<0>>>, %ptrs2: vector<8x!ptr.ptr<#llvm.address_space<0>>>) -> vector<8xi32> {
  %diffs = ptr.ptr_diff %ptrs1, %ptrs2 : vector<8x!ptr.ptr<#llvm.address_space<0>>> -> vector<8xi32>
  llvm.return %diffs : vector<8xi32>
}
```
Translation to LLVM IR:
```llvm
define <8 x i32> @ptr_diff_vector_i32(<8 x ptr> %0, <8 x ptr> %1) {
  %3 = ptrtoint <8 x ptr> %0 to <8 x i64>
  %4 = ptrtoint <8 x ptr> %1 to <8 x i64>
  %5 = sub <8 x i64> %3, %4
  %6 = trunc <8 x i64> %5 to <8 x i32>
  ret <8 x i32> %6
}
```

---------

Co-authored-by: Mehdi Amini <joker.eph at gmail.com>



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