Kernel state rewrite messes up debug info

[vchuravy]

I believe I have bisected EnzymeAD/Enzyme.jl#533 to an issue with the kernelstate lowering.

I inserted a call to verify after and before

GPUCompiler.jl/src/optim.jl

Line 185 in dda3e52

@dispose pm=ModulePassManager() begin

My hypothesis is that we do replace_metadata_uses! but that maybe doesn't handle the debuginfo?

ERROR: LoadError: LLVM error: mismatched subprogram between llvm.dbg.declare variable and !dbg attachment
  call void @llvm.dbg.declare(metadata { i8 addrspace(1)*, i64, [1 x i64], i64 }* undef, metadata !173, metadata !DIExpression(DW_OP_deref)), !dbg !178
label %conversion
void ([1 x i64], { i8 addrspace(1)*, i64, [1 x i64], i64 }, { i8 addrspace(1)*, i64, [1 x i64], i64 })* @_Z23julia_grad_kernel__291613CuDeviceArrayI7Float32Li1ELi1EES_IS0_Li1ELi1EE
!173 = !DILocalVariable(name: "a", arg: 2, scope: !174, file: !4, line: 10, type: !86)
!174 = distinct !DISubprogram(name: "grad_kernel!", linkageName: "julia_grad_kernel!_2916", scope: null, file: !4, line: 10, type: !166, scopeLine: 10, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !3, retainedNodes: !175)
!178 = !DILocation(line: 10, scope: !165)
!165 = distinct !DISubprogram(name: "grad_kernel!", linkageName: "julia_grad_kernel!_2916", scope: null, file: !4, line: 10, type: !166, scopeLine: 10, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !3, retainedNodes: !169)
mismatched subprogram between llvm.dbg.declare variable and !dbg attachment
  call void @llvm.dbg.declare(metadata { i8 addrspace(1)*, i64, [1 x i64], i64 }* undef, metadata !177, metadata !DIExpression(DW_OP_deref)), !dbg !178
label %conversion
void ([1 x i64], { i8 addrspace(1)*, i64, [1 x i64], i64 }, { i8 addrspace(1)*, i64, [1 x i64], i64 })* @_Z23julia_grad_kernel__291613CuDeviceArrayI7Float32Li1ELi1EES_IS0_Li1ELi1EE
!177 = !DILocalVariable(name: "da", arg: 3, scope: !174, file: !4, line: 10, type: !86)
!174 = distinct !DISubprogram(name: "grad_kernel!", linkageName: "julia_grad_kernel!_2916", scope: null, file: !4, line: 10, type: !166, scopeLine: 10, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !3, retainedNodes: !175)
!178 = !DILocation(line: 10, scope: !165)
!165 = distinct !DISubprogram(name: "grad_kernel!", linkageName: "julia_grad_kernel!_2916", scope: null, file: !4, line: 10, type: !166, scopeLine: 10, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !3, retainedNodes: !169)