[all-commits] [llvm/llvm-project] 11b040: [AMDGPU] Restore SP from saved-FP or saved-BP (#12...

[Aaditya via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 11b040192640ef3b1f481124c440f464ed6ec86a
      https://github.com/llvm/llvm-project/commit/11b040192640ef3b1f481124c440f464ed6ec86a
  Author: Aaditya <115080342+easyonaadit at users.noreply.github.com>
  Date:   2025-01-24 (Fri, 24 Jan 2025)

  Changed paths:
    M llvm/lib/Target/AMDGPU/SIFrameLowering.cpp
    M llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
    M llvm/test/CodeGen/AMDGPU/GlobalISel/assert-align.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/call-outgoing-stack-args.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/dynamic-alloca-uniform.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/localizer.ll
    M llvm/test/CodeGen/AMDGPU/GlobalISel/non-entry-alloca.ll
    M llvm/test/CodeGen/AMDGPU/abi-attribute-hints-undefined-behavior.ll
    M llvm/test/CodeGen/AMDGPU/amdgpu-simplify-libcall-pow-codegen.ll
    M llvm/test/CodeGen/AMDGPU/bf16.ll
    M llvm/test/CodeGen/AMDGPU/buffer-fat-pointers-contents-legalization.ll
    M llvm/test/CodeGen/AMDGPU/call-args-inreg.ll
    M llvm/test/CodeGen/AMDGPU/call-argument-types.ll
    M llvm/test/CodeGen/AMDGPU/callee-frame-setup.ll
    M llvm/test/CodeGen/AMDGPU/callee-special-input-vgprs-packed.ll
    M llvm/test/CodeGen/AMDGPU/callee-special-input-vgprs.ll
    M llvm/test/CodeGen/AMDGPU/cross-block-use-is-not-abi-copy.ll
    M llvm/test/CodeGen/AMDGPU/dwarf-multi-register-use-crash.ll
    M llvm/test/CodeGen/AMDGPU/dynamic_stackalloc.ll
    M llvm/test/CodeGen/AMDGPU/eliminate-frame-index-v-add-co-u32.mir
    M llvm/test/CodeGen/AMDGPU/eliminate-frame-index-v-add-u32.mir
    M llvm/test/CodeGen/AMDGPU/fix-frame-reg-in-custom-csr-spills.ll
    M llvm/test/CodeGen/AMDGPU/frame-setup-without-sgpr-to-vgpr-spills.ll
    M llvm/test/CodeGen/AMDGPU/function-args-inreg.ll
    M llvm/test/CodeGen/AMDGPU/gfx-call-non-gfx-func.ll
    M llvm/test/CodeGen/AMDGPU/gfx-callable-argument-types.ll
    M llvm/test/CodeGen/AMDGPU/gfx-callable-preserved-registers.ll
    M llvm/test/CodeGen/AMDGPU/gfx-callable-return-types.ll
    M llvm/test/CodeGen/AMDGPU/global-alias.ll
    M llvm/test/CodeGen/AMDGPU/indirect-call.ll
    M llvm/test/CodeGen/AMDGPU/insert-delay-alu-bug.ll
    M llvm/test/CodeGen/AMDGPU/insert-waitcnts-crash.ll
    M llvm/test/CodeGen/AMDGPU/local-stack-alloc-block-sp-reference.ll
    M llvm/test/CodeGen/AMDGPU/materialize-frame-index-sgpr.gfx10.ll
    M llvm/test/CodeGen/AMDGPU/mul24-pass-ordering.ll
    M llvm/test/CodeGen/AMDGPU/need-fp-from-vgpr-spills.ll
    M llvm/test/CodeGen/AMDGPU/nested-calls.ll
    M llvm/test/CodeGen/AMDGPU/no-source-locations-in-prologue.ll
    M llvm/test/CodeGen/AMDGPU/non-entry-alloca.ll
    M llvm/test/CodeGen/AMDGPU/pei-scavenge-sgpr-carry-out.mir
    M llvm/test/CodeGen/AMDGPU/pei-scavenge-sgpr-gfx9.mir
    M llvm/test/CodeGen/AMDGPU/pei-scavenge-sgpr.mir
    M llvm/test/CodeGen/AMDGPU/pei-scavenge-vgpr-spill.mir
    M llvm/test/CodeGen/AMDGPU/preserve-wwm-copy-dst-reg.ll
    M llvm/test/CodeGen/AMDGPU/schedule-amdgpu-trackers.ll
    M llvm/test/CodeGen/AMDGPU/sgpr-spill-overlap-wwm-reserve.mir
    M llvm/test/CodeGen/AMDGPU/sgpr-spills-split-regalloc.ll
    M llvm/test/CodeGen/AMDGPU/sibling-call.ll
    M llvm/test/CodeGen/AMDGPU/stack-realign.ll
    M llvm/test/CodeGen/AMDGPU/stacksave_stackrestore.ll
    M llvm/test/CodeGen/AMDGPU/strictfp_f16_abi_promote.ll
    M llvm/test/CodeGen/AMDGPU/tail-call-inreg-arguments.error.ll
    M llvm/test/CodeGen/AMDGPU/unstructured-cfg-def-use-issue.ll
    M llvm/test/CodeGen/AMDGPU/use_restore_frame_reg.mir
    M llvm/test/CodeGen/AMDGPU/vgpr-tuple-allocation.ll
    M llvm/test/CodeGen/AMDGPU/wave32.ll
    M llvm/test/CodeGen/AMDGPU/whole-wave-register-copy.ll
    M llvm/test/CodeGen/AMDGPU/whole-wave-register-spill.ll
    M llvm/test/CodeGen/AMDGPU/wwm-reserved-spill.ll
    M llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/amdgpu_generated_funcs.ll.generated.expected
    M llvm/test/tools/UpdateTestChecks/update_llc_test_checks/Inputs/amdgpu_generated_funcs.ll.nogenerated.expected

  Log Message:
  -----------
  [AMDGPU] Restore SP from saved-FP or saved-BP (#124007)

Currently, the AMDGPU backend bumps the Stack Pointer 
by fixed size offsets in the prolog of device functions, and 
restores it by the same amount in the epilog.
Prolog:
sp += frameSize

Epilog:
sp -= frameSize

If a function has dynamic stack realignment,
Prolog:
sp += frameSize + max_alignment

Epilog:
sp -= frameSize + max_alignment

These calculations are not optimal in case of dynamic 
stack realignment, and completely fail in case of 
dynamic stack readjustment.
This patch uses the saved Frame Pointer to restore SP. 
Prolog:
fp = sp
sp += frameSize

Epilog:
sp = fp

In case of dynamic stack realignment, SP is restored from 
the saved Base Pointer. 
Prolog:
fp = sp + (max_alignment - 1)
fp = fp & (-max_alignment)
bp = sp
sp += frameSize + max_alignment

Epilog:
sp = bp

(Note: The presence of BP has been enforced in case of any 
dynamic stack realignment.)

---------

Co-authored-by: Pravin Jagtap <Pravin.Jagtap at amd.com>
Co-authored-by: Matt Arsenault <arsenm2 at gmail.com>



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