[all-commits] [llvm/llvm-project] aeec2c: [VPlan] Speed up VPSlotTracker by using ModuleSlot...

[Igor Kirillov via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: aeec2c6e489364525a1c293248b7657d7e07726f
      https://github.com/llvm/llvm-project/commit/aeec2c6e489364525a1c293248b7657d7e07726f
  Author: Igor Kirillov <igor.kirillov at arm.com>
  Date:   2025-06-26 (Thu, 26 Jun 2025)

  Changed paths:
    M llvm/lib/Transforms/Vectorize/VPlan.cpp
    M llvm/lib/Transforms/Vectorize/VPlanHelpers.h

  Log Message:
  -----------
  [VPlan] Speed up VPSlotTracker by using ModuleSlotTracker (#139881)

Currently, when VPSlotTracker is initialized with a VPlan, its
assignName method calls printAsOperand on each underlying instruction.
Each such call recomputes slot numbers for the entire function, leading
to O(N × M) complexity, where M is the number of instructions in the
loop and N is the number of instructions in the function.

This results in slow debug output for large loops. For example, printing
costs of all instructions becomes O(M² × N), which is especially painful
when enabling verbose dumps.

This patch improves debugging performance by caching slot numbers using
ModuleSlotTracker. It avoids redundant recomputation and makes debug
output significantly faster.



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