LLVM assertion error on PPC

[vchuravy]

While looking into power support I am encountering an assertion failure in LLVM, after applying #26218.

julia: /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/Instructions.cpp:2648: static llvm::CastInst* llvm::CastInst::Create(llvm::Instruction::CastOps, llvm::Value*, llvm::Type*, const llvm::Twine&, llvm::Instruction*): Assertion `castIsValid(op, S, Ty) && "Invalid cast!"' failed.

signal (6): Aborted
in expression starting at sysimg.jl:8
gsignal at /lib64/libc.so.6 (unknown line)
abort at /lib64/libc.so.6 (unknown line)
__assert_fail_base at /lib64/libc.so.6 (unknown line)
__assert_fail at /lib64/libc.so.6 (unknown line)
Create at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/Instructions.cpp:2648
CreateCast at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/include/llvm/IR/IRBuilder.h:1365
CreateBitCast at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/include/llvm/IR/IRBuilder.h:1329 [inlined]
optimizeMemoryInst at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/CodeGen/CodeGenPrepare.cpp:3942
optimizeInst at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/CodeGen/CodeGenPrepare.cpp:5250
optimizeBlock at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/CodeGen/CodeGenPrepare.cpp:5325 [inlined]
runOnFunction at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/CodeGen/CodeGenPrepare.cpp:272
runOnFunction at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/LegacyPassManager.cpp:1526
runOnModule at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/LegacyPassManager.cpp:1547
runOnModule at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/LegacyPassManager.cpp:1603 [inlined]
run at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/LegacyPassManager.cpp:1706
run at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/LegacyPassManager.cpp:1737
operator() at /raid1/home/ibm/valentin/src/julia/src/jitlayers.cpp:465

Bisect log: https://gist.github.com/vchuravy/ad88db5f56688c0538d9bade8ea7dfed
Bisect is not as helpful as I would have hoped since some of the commits are not testable, but everything points towards #21888 (cc: @Keno )

(gdb) f 4
#4  0x00001000012c0848 in llvm::CastInst::Create (op=<optimized out>, S=0x102d8448, Ty=0x1016d400, Name=..., 
    InsertBefore=0x0) at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/lib/IR/Instructions.cpp:2648
2648      assert(castIsValid(op, S, Ty) && "Invalid cast!");
(gdb) f 5
#5  0x00001000011f7944 in llvm::IRBuilder<llvm::ConstantFolder, llvm::IRBuilderDefaultInserter>::CreateCast (
    this=0x3fffffff3400, Op=<optimized out>, V=0x102d8448, DestTy=0x1016d400, Name=...)
    at /raid1/home/ibm/valentin/src/julia/deps/srccache/llvm-3.9.1/include/llvm/IR/IRBuilder.h:1365
1365        return Insert(CastInst::Create(Op, V, DestTy), Name);
(gdb) call V->dump()
  %18 = load %jl_value_t addrspace(10)*, %jl_value_t addrspace(10)** %1, !nonnull !4, !dereferenceable !10
(gdb) call DestTy->dump()
i8 addrspace(11)*
(gdb) p Op               
$4 = llvm::Instruction::BitCast
(gdb) f 9
(gdb) p BB.dump()

ok17:                                             ; preds = %L60
  %282 = bitcast %jl_value_t addrspace(11)* %70 to i8 addrspace(11)*
  %283 = load %jl_value_t*, %jl_value_t** @"*Main.Core.Compiler.setproperty!55", !dbg !35, !tbaa !13
  %284 = getelementptr i8, i8 addrspace(11)* %282, i64 16, !dbg !35
  %285 = bitcast i8 addrspace(11)* %284 to %jl_value_t addrspace(10)* addrspace(11)*, !dbg !35
  store %jl_value_t addrspace(10)* %278, %jl_value_t addrspace(10)* addrspace(11)* %285, !dbg !35, !tbaa !15
  %286 = bitcast %jl_value_t addrspace(10)* %18 to i64 addrspace(10)*, !dbg !35
  %287 = getelementptr i64, i64 addrspace(10)* %286, i64 -1, !dbg !35
  %288 = load i64, i64 addrspace(10)* %287, !dbg !35, !tbaa !19, !range !21
  %289 = and i64 %288, 3, !dbg !35
  %290 = icmp eq i64 %289, 3, !dbg !35
  br i1 %290, label %291, label %298, !dbg !35

According to the debug information !dbg !35 this is coming from compiler/typeinfer.jl:243 on vc/ppc_as

[vchuravy]

fixed by fad170c, found through bugpoint and bisect.