Fix late gc lowering pass for vector intrinsics

[gbaraldi]

No description provided.

[vchuravy]

if(auto IdxOp = dyn_cast<ConstantInt>...? Otherwise, this would assert for non ConstantInt?
Also add a test for this?

[gbaraldi]

This is an assertion. This argument is a immarg argument in llvm

[vchuravy]

Then I don't understand the todo?

[Zentrik]

JULIA_CPU_TARGET="sandybridge,-xsaveopt,clone_all;x86-64-v4,-rdrnd" is a more minimal reproducer for the build failure.

Looking at the coredump I get locally, I see its indexing out of bounds at

julia/src/llvm-late-gc-lowering.cpp

Line 567 in 4843847

Numbers.push_back(BaseNumbers[i]);

but

julia/src/llvm-late-gc-lowering.cpp

Line 560 in 4843847

assert(Tracked.size() == BaseNumbers.size());

should make sure that can't happen so I don't understand what's going on. I added a if statement to check if i >= BaseNumbers.size() and it never got hit.

Here's part of the backtrace form the core dump.

#12 0x0000730004148a26 in llvm::SmallVectorTemplateCommon<int, void>::operator[] (idx=<optimised out>, this=<optimised out>) at /home/rag/Documents/Code/julia/usr/include/llvm/ADT/SmallVector.h:291
#13 LateLowerGCFrame::NumberAllBase (this=this@entry=0x72ffe3ffd500, S=..., CurrentV=<optimised out>, CurrentV@entry=0x72ffad005810) at /home/rag/Documents/Code/julia/src/llvm-late-gc-lowering.cpp:567
#14 0x000073000414cc17 in LateLowerGCFrame::NumberAll (this=this@entry=0x72ffe3ffd500, S=..., V=<optimised out>, V@entry=0x72ffad005810) at /home/rag/Documents/Code/julia/src/llvm-late-gc-lowering.cpp:630
#15 0x000073000414d381 in LateLowerGCFrame::NoteUse (this=this@entry=0x72ffe3ffd500, S=..., V=0x72ffad005810, Uses=..., F=..., BBS=...) at /home/rag/Documents/Code/julia/src/llvm-late-gc-lowering.cpp:739

#16 0x000073000414d524 in LateLowerGCFrame::NoteUse (BBS=..., F=..., Uses=..., V=<optimised out>, S=..., this=0x72ffe3ffd500) at /home/rag/Documents/Code/julia/usr/include/llvm/IR/Value.h:533
#17 LateLowerGCFrame::NoteUse (F=..., V=<optimised out>, BBS=..., S=..., this=0x72ffe3ffd500) at /home/rag/Documents/Code/julia/src/llvm-gc-interface-passes.h:336
#18 LateLowerGCFrame::NoteOperandUses (this=this@entry=0x72ffe3ffd500, S=..., BBS=..., UI=...) at /home/rag/Documents/Code/julia/src/llvm-late-gc-lowering.cpp:751
#19 0x000073000414f611 in LateLowerGCFrame::LocalScan (this=this@entry=0x72ffe3ffd500, F=...) at /home/rag/Documents/Code/julia/src/llvm-late-gc-lowering.cpp:1419
#20 0x000073000414fc2d in LateLowerGCFrame::runOnFunction (this=0x72ffe3ffd500, F=..., CFGModified=0x72ffe3ffd4ef) at /home/rag/Documents/Code/julia/src/llvm-late-gc-lowering.cpp:2490
#21 0x000073000415015e in LateLowerGCPass::run (this=<optimised out>, F=..., AM=...) at /home/rag/Documents/Code/julia/src/llvm-late-gc-lowering.cpp:2506

[giordano]

Note that this is necessary to upgrade to LLVM 20: #57352.