| Issue |
177772
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| Summary |
[VPlan] f527.cam4_r asserts in loop vectorizer " VPlan cost model and legacy cost model disagreed"
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| Labels |
new issue
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| Assignees |
|
| Reporter |
anoopkg6
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f527.cam4_r benchmark asserts in loop vectorizer with message " VPlan cost model and legacy cost model disagreed".
%opt -O3 cam4_r_reduced.ll
WARNING: You're attempting to print out a bitcode file.
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can force output with the `-f' option.
opt: /home/anoopk/fllvm/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:7276: llvm::VectorizationFactor llvm::LoopVectorizationPlanner::computeBestVF(): Assertion `(BestFactor.Width == LegacyVF.Width || BestPlan.hasEarlyExit() || !Legal->getLAI()->getSymbolicStrides().empty() || UsesEVLGatherScatter || planContainsAdditionalSimplifications( getPlanFor(BestFactor.Width), CostCtx, OrigLoop, BestFactor.Width) || planContainsAdditionalSimplifications( getPlanFor(LegacyVF.Width), CostCtx, OrigLoop, LegacyVF.Width)) && " VPlan cost model and legacy cost model disagreed"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace and instructions to reproduce the bug.
Stack dump:
0. Program arguments: opt -O3 cam4_r_reduced.ll
1. Running pass "function<eager-inv>(drop-unnecessary-assumes,float2int,lower-constant-intrinsics,chr,loop(loop-rotate<header-duplication;no-prepare-for-lto>,loop-deletion),loop-distribute,inject-tli-mappings,loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>,drop-unnecessary-assumes,infer-alignment,loop-load-elim,instcombine<max-iterations=1;no-verify-fixpoint>,simplifycfg<bonus-inst-threshold=1;forward-switch-cond;switch-range-to-icmp;switch-to-arithmetic;switch-to-lookup;no-keep-loops;hoist-common-insts;no-hoist-loads-stores-with-cond-faulting;sink-common-insts;speculate-blocks;simplify-cond-branch;no-speculate-unpredictables>,slp-vectorizer,vector-combine,instcombine<max-iterations=1;no-verify-fixpoint>,loop-unroll<O3>,transform-warning,sroa<preserve-cfg>,infer-alignment,instcombine<max-iterations=1;no-verify-fixpoint>,loop-mssa(licm<allowspeculation>),alignment-from-assumptions,loop-sink,instsimplify,div-rem-pairs,tailcallelim,simplifycfg<bonus-inst-threshold=1;no-forward-switch-cond;switch-range-to-icmp;switch-to-arithmetic;no-switch-to-lookup;keep-loops;no-hoist-common-insts;hoist-loads-stores-with-cond-faulting;no-sink-common-insts;speculate-blocks;simplify-cond-branch;speculate-unpredictables>)" on module "cam4_r_reduced.ll"
2. Running pass "loop-vectorize<no-interleave-forced-only;no-vectorize-forced-only;>" on function "_QMzm_convPzm_convr"
#0 0x00000000046cdc64 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x46cdc64)
#1 0x00000000046caa74 SignalHandler(int, siginfo_t*, void*) Signals.cpp:0:0
#2 0x000003ffd43934e0 (linux-vdso.so.1+0x4e0)
#3 0x000003ffb30b07d0 __pthread_kill_implementation (/lib64/libc.so.6+0xb07d0)
#4 0x000003ffb30550c0 gsignal (/lib64/libc.so.6+0x550c0)
#5 0x000003ffb3034242 abort (/lib64/libc.so.6+0x34242)
#6 0x000003ffb304bdcc __assert_fail_base (/lib64/libc.so.6+0x4bdcc)
#7 0x000003ffb304c0e4 __assert_fail (/lib64/libc.so.6+0x4c0e4)
#8 0x0000000001f0ccd8 llvm::LoopVectorizationPlanner::computeBestVF() (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x1f0ccd8)
#9 0x0000000001f0eb08 llvm::LoopVectorizePass::processLoop(llvm::Loop*) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x1f0eb08)
#10 0x0000000001f11cd2 llvm::LoopVectorizePass::runImpl(llvm::Function&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x1f11cd2)
#11 0x0000000001f1226c llvm::LoopVectorizePass::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x1f1226c)
#12 0x0000000001655caa llvm::detail::PassModel<llvm::Function, llvm::LoopVectorizePass, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x1655caa)
#13 0x00000000043e9736 llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x43e9736)
#14 0x000000000165755a llvm::detail::PassModel<llvm::Function, llvm::PassManager<llvm::Function, llvm::AnalysisManager<llvm::Function>>, llvm::AnalysisManager<llvm::Function>>::run(llvm::Function&, llvm::AnalysisManager<llvm::Function>&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x165755a)
#15 0x00000000043ea17c llvm::ModuleToFunctionPassAdaptor::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x43ea17c)
#16 0x0000000001421b9a llvm::detail::PassModel<llvm::Module, llvm::ModuleToFunctionPassAdaptor, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x1421b9a)
#17 0x00000000043ec526 llvm::PassManager<llvm::Module, llvm::AnalysisManager<llvm::Module>>::run(llvm::Module&, llvm::AnalysisManager<llvm::Module>&) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x43ec526)
#18 0x000000000142de8e llvm::runPassPipeline(llvm::StringRef, llvm::Module&, llvm::TargetMachine*, llvm::TargetLibraryInfoImpl*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::ToolOutputFile*, llvm::StringRef, llvm::ArrayRef<llvm::PassPlugin>, llvm::ArrayRef<std::function<void (llvm::PassBuilder&)>>, llvm::opt_tool::OutputKind, llvm::opt_tool::VerifierKind, bool, bool, bool, bool, bool, bool, bool, bool) (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x142de8e)
#19 0x000000000141fe8c optMain (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x141fe8c)
#20 0x00000000013359d2 main (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x13359d2)
#21 0x000003ffb30348cc __libc_start_call_main (/lib64/libc.so.6+0x348cc)
#22 0x000003ffb30349c6 __libc_start_main@GLIBC_2.2 (/lib64/libc.so.6+0x349c6)
#23 0x0000000001414ada _start (/home/anoopk/fllvm/llvm-project/build/bin/opt+0x1414ada)
Aborted (core dumped) opt -O3 cam4_r_reduced.ll
[cam4_r.zip](https://github.com/user-attachments/files/24837823/cam4_r.zip)
cam4_r_reduced.ll is produced by llvm-reduced on asserting function ir in cam4_r_test.ll and original fortran function is in cam4_r_test.f90 from f527.cam4_r.
Following commit seems to have caused it.
commit b4be7ecaf06bfcb4aa8d47c4fda1eed9bbe4ae77
Author: Florian Hahn <[email protected]>
Date: Mon Sep 29 09:08:09 2025 +0100
[VPlan] Compute cost of more replicating loads/stores in ::computeCost. (#160053)
Update VPReplicateRecipe::computeCost to compute costs of more
replicating loads/stores.
There are 2 cases that require extra checks to match the legacy cost
model:
1. If the pointer is based on an induction, the legacy cost model passes
its SCEV to getAddressComputationCost. In those cases, still fall back
to the legacy cost. SCEV computations will be added as follow-up
2. If a load is used as part of an address of another load, the legacy
cost model skips the scalarization overhead. Those cases are currently
handled by a usedByLoadOrStore helper.
Note that getScalarizationOverhead also needs updating, because when the
legacy cost model computes the scalarization overhead, scalars have not
been collected yet, so we can't each for replicating recipes to skip
their cost, except other loads. This again can be further improved by
modeling inserts/extracts explicitly and consistently, and compute costs
for those operations directly where needed.
PR: https://github.com/llvm/llvm-project/pull/160053
llvm/lib/Transforms/Vectorize/LoopVectorize.cpp | 16 ++--
llvm/lib/Transforms/Vectorize/VPlan.cpp | 7 +-
llvm/lib/Transforms/Vectorize/VPlanHelpers.h | 16 ++--
llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp | 118 +++++++++++++++++++++---
4 files changed, 130 insertions(+), 27 deletions(-)
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