[all-commits] [llvm/llvm-project] 87bab3: [Flang] - Add optional inlining of allocatable ass...

[Pranav Bhandarkar via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 87bab31c27dee5ec69022df3beaa018744c4e8d1
      https://github.com/llvm/llvm-project/commit/87bab31c27dee5ec69022df3beaa018744c4e8d1
  Author: Pranav Bhandarkar <pranav.bhandarkar at amd.com>
  Date:   2026-03-23 (Mon, 23 Mar 2026)

  Changed paths:
    M flang/lib/Optimizer/HLFIR/Transforms/InlineHLFIRAssign.cpp
    A flang/test/HLFIR/inline-hlfir-assign-allocatable-expr.fir

  Log Message:
  -----------
  [Flang] - Add optional inlining of allocatable assignments with hlfir.expr RHS (#186880)

Add support for inlining hlfir.assign operations where the LHS is an
allocatable and the RHS is an `hlfir.expr` (e.g., from
`hlfir.elemental`). Since `hlfir.expr` values cannot alias with memory
locations, these assignments can be safely inlined without alias
analysis.

The optimization is controlled by the
-inline-hlfir-allocatable-expr-assign flag:
fir-opt -inline-hlfir-allocatable-expr-assign --inline-hlfir-assign
file.fir
  flang -mmlir -inline-hlfir-allocatable-expr-assign file.f90

The generated code uses `fir::factory::genReallocIfNeeded` to properly
handle Fortran allocatable assignment semantics (F2018 10.2.1.3):
- If not allocated: allocate with RHS shape
- If allocated with same shape: reuse existing allocation
- If allocated with different shape: reallocate

This is motivated by the increased link time that I am seeing when
`__FortranAAssign` is called from the user code. The details of the
problem are documented in
https://github.com/llvm/llvm-project/issues/187720



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