[FR]: Example feature request #1
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Seelengrab
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Aug 8, 2023
This makes it easier to correlate LLVM IR with the originating source
code by including both argument name and argument type in the LLVM
argument variable.
<details>
<summary>Example 1</summary>
```julia
julia> function f(a, b, c, d, g...)
e = a + b + c + d
f = does_not_exist(e) + e
f
end
f (generic function with 1 method)
julia> @code_llvm f(0,0,0,0,0)
```
```llvm
; @ REPL[1]:1 within `f`
define nonnull {}* @julia_f_141(i64 signext %"a::Int64", i64 signext %"b::Int64", i64 signext %"c::Int64", i64 signext %"d::Int64", i64 signext %"g[0]::Int64") #0 {
top:
%0 = alloca [2 x {}*], align 8
%gcframe3 = alloca [4 x {}*], align 16
%gcframe3.sub = getelementptr inbounds [4 x {}*], [4 x {}*]* %gcframe3, i64 0, i64 0
%1 = bitcast [4 x {}*]* %gcframe3 to i8*
call void @llvm.memset.p0i8.i64(i8* align 16 %1, i8 0, i64 32, i1 true)
%thread_ptr = call i8* asm "movq %fs:0, $0", "=r"() JuliaLang#7
%tls_ppgcstack = getelementptr i8, i8* %thread_ptr, i64 -8
%2 = bitcast i8* %tls_ppgcstack to {}****
%tls_pgcstack = load {}***, {}**** %2, align 8
; @ REPL[1]:3 within `f`
%3 = bitcast [4 x {}*]* %gcframe3 to i64*
store i64 8, i64* %3, align 16
%4 = getelementptr inbounds [4 x {}*], [4 x {}*]* %gcframe3, i64 0, i64 1
%5 = bitcast {}** %4 to {}***
%6 = load {}**, {}*** %tls_pgcstack, align 8
store {}** %6, {}*** %5, align 8
%7 = bitcast {}*** %tls_pgcstack to {}***
store {}** %gcframe3.sub, {}*** %7, align 8
%Main.does_not_exist.cached = load atomic {}*, {}** @0 unordered, align 8
%iscached.not = icmp eq {}* %Main.does_not_exist.cached, null
br i1 %iscached.not, label %notfound, label %found
notfound: ; preds = %top
%Main.does_not_exist.found = call {}* @ijl_get_binding_or_error({}* nonnull inttoptr (i64 139831437630272 to {}*), {}* nonnull inttoptr (i64 139831600565400 to {}*))
store atomic {}* %Main.does_not_exist.found, {}** @0 release, align 8
br label %found
found: ; preds = %notfound, %top
%Main.does_not_exist = phi {}* [ %Main.does_not_exist.cached, %top ], [ %Main.does_not_exist.found, %notfound ]
%8 = bitcast {}* %Main.does_not_exist to {}**
%does_not_exist.checked = load atomic {}*, {}** %8 unordered, align 8
%.not = icmp eq {}* %does_not_exist.checked, null
br i1 %.not, label %err, label %ok
err: ; preds = %found
call void @ijl_undefined_var_error({}* inttoptr (i64 139831600565400 to {}*))
unreachable
ok: ; preds = %found
%.sub = getelementptr inbounds [2 x {}*], [2 x {}*]* %0, i64 0, i64 0
; @ REPL[1]:2 within `f`
; ┌ @ operators.jl:587 within `+` @ int.jl:87
%9 = add i64 %"b::Int64", %"a::Int64"
%10 = add i64 %9, %"c::Int64"
; │ @ operators.jl:587 within `+`
; │┌ @ operators.jl:544 within `afoldl`
; ││┌ @ int.jl:87 within `+`
%11 = add i64 %10, %"d::Int64"
%12 = getelementptr inbounds [4 x {}*], [4 x {}*]* %gcframe3, i64 0, i64 3
store {}* %does_not_exist.checked, {}** %12, align 8
; └└└
; @ REPL[1]:3 within `f`
%13 = call nonnull {}* @ijl_box_int64(i64 signext %11)
%14 = getelementptr inbounds [4 x {}*], [4 x {}*]* %gcframe3, i64 0, i64 2
store {}* %13, {}** %14, align 16
store {}* %13, {}** %.sub, align 8
%15 = call nonnull {}* @ijl_apply_generic({}* nonnull %does_not_exist.checked, {}** nonnull %.sub, i32 1)
store {}* %15, {}** %12, align 8
%16 = call nonnull {}* @ijl_box_int64(i64 signext %11)
store {}* %16, {}** %14, align 16
store {}* %15, {}** %.sub, align 8
%17 = getelementptr inbounds [2 x {}*], [2 x {}*]* %0, i64 0, i64 1
store {}* %16, {}** %17, align 8
%18 = call nonnull {}* @ijl_apply_generic({}* inttoptr (i64 139831370516384 to {}*), {}** nonnull %.sub, i32 2)
%19 = load {}*, {}** %4, align 8
%20 = bitcast {}*** %tls_pgcstack to {}**
store {}* %19, {}** %20, align 8
; @ REPL[1]:4 within `f`
ret {}* %18
}
```
</details>
<details>
<summary>Example 2</summary>
```julia
julia> function g(a, b, c, d; kwarg=0)
a + b + c + d + kwarg
end
g (generic function with 1 method)
julia> @code_llvm g(0,0,0,0,kwarg=0)
```
```llvm
; @ REPL[3]:1 within `g`
define i64 @julia_g_160([1 x i64]* nocapture noundef nonnull readonly align 8 dereferenceable(8) %"#1::NamedTuple", i64 signext %"a::Int64", i64 signext %"b::Int64", i64 signext %"c::Int64", i64 signext %"d::Int64") #0 {
top:
%0 = getelementptr inbounds [1 x i64], [1 x i64]* %"#1::NamedTuple", i64 0, i64 0
; ┌ @ REPL[3]:2 within `#g#1`
; │┌ @ operators.jl:587 within `+` @ int.jl:87
%1 = add i64 %"b::Int64", %"a::Int64"
%2 = add i64 %1, %"c::Int64"
; ││ @ operators.jl:587 within `+`
; ││┌ @ operators.jl:544 within `afoldl`
; │││┌ @ int.jl:87 within `+`
%3 = add i64 %2, %"d::Int64"
; │││└
; │││ @ operators.jl:545 within `afoldl`
; │││┌ @ int.jl:87 within `+`
%unbox = load i64, i64* %0, align 8
%4 = add i64 %3, %unbox
; └└└└
ret i64 %4
}
```
</details>
Seelengrab
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Nov 9, 2023
…#51489) This exposes the GC "stop the world" API to the user, for causing a thread to quickly stop executing Julia code. This adds two APIs (that will need to be exported and documented later): ``` julia> @CCall jl_safepoint_suspend_thread(#=tid=#1::Cint, #=magicnumber=#2::Cint)::Cint # roughly tkill(1, SIGSTOP) julia> @CCall jl_safepoint_resume_thread(#=tid=#1::Cint)::Cint # roughly tkill(1, SIGCONT) ``` You can even suspend yourself, if there is another task to resume you 10 seconds later: ``` julia> ccall(:jl_enter_threaded_region, Cvoid, ()) julia> t = @task let; Libc.systemsleep(10); print("\nhello from $(Threads.threadid())\n"); @CCall jl_safepoint_resume_thread(0::Cint)::Cint; end; ccall(:jl_set_task_tid, Cint, (Any, Cint), t, 1); schedule(t); julia> @time @CCall jl_safepoint_suspend_thread(0::Cint, 2::Cint)::Cint hello from 2 10 seconds (6 allocations: 264 bytes) 1 ``` The meaning of the magic number is actually the kind of stop that you want: ``` // n.b. suspended threads may still run in the GC or GC safe regions // but shouldn't be observable, depending on which enum the user picks (only 1 and 2 are typically recommended here) // waitstate = 0 : do not wait for suspend to finish // waitstate = 1 : wait for gc_state != 0 (JL_GC_STATE_WAITING or JL_GC_STATE_SAFE) // waitstate = 2 : wait for gc_state != 0 (JL_GC_STATE_WAITING or JL_GC_STATE_SAFE) and that GC is not running on that thread // waitstate = 3 : wait for full suspend (gc_state == JL_GC_STATE_WAITING) -- this may never happen if thread is sleeping currently // if another thread comes along and calls jl_safepoint_resume, we also return early // return new suspend count on success, 0 on failure ``` Only magic number 2 is currently meaningful to the user though. The difference between waitstate 1 and 2 is only relevant in C code which is calling this from JL_GC_STATE_SAFE, since otherwise it is a priori known that GC isn't running, else we too would be running the GC. But the distinction of those states might be useful if we have a concurrent collector. Very important warning: if the stopped thread is holding any locks (e.g. for codegen or types) that you then attempt to acquire, your thread will deadlock. This is very likely, unless you are very careful. A future update to this API may try to change the waitstate to give the option to wait for the thread to release internal or known locks.
Seelengrab
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Mar 13, 2024
…ang#53631) This PR validates the input parameters to the Julia LAPACK wrappers, so that the error messages are more informative. On nightly ```julia julia> using LinearAlgebra julia> LAPACK.geev!('X', 'X', rand(2,2)) ** On entry to DGEEV parameter number 1 had an illegal value ERROR: ArgumentError: invalid argument #1 to LAPACK call ``` This PR ```julia julia> using LinearAlgebra julia> LAPACK.geev!('X', 'X', rand(2,2)) ERROR: ArgumentError: argument #1: jobvl must be one of ('N', 'V'), but 'X' was passed ``` Secondly, moved certain allocations (e.g. in `geevx`) below the validation checks, so that these only happen for valid parameter values. Thirdly, added `require_one_based_indexing` checks to functions where these were missing.
Seelengrab
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Apr 6, 2024
This is an alternative to JuliaLang#53642 The `dom_edges()` for an exit block in the CFG are empty when computing the PostDomTree so the loop below this may not actually run. In that case, the right semidominator is the ancestor from the DFSTree, which is the "virtual" -1 block. This resolves half of the issue in JuliaLang#53613: ```julia julia> let code = Any[ # block 1 GotoIfNot(Argument(2), 3), # block 2 ReturnNode(Argument(3)), # block 3 (we should visit this block) Expr(:call, throw, "potential throw"), ReturnNode(), # unreachable ] ir = make_ircode(code; slottypes=Any[Any,Bool,Bool]) visited = BitSet() @test !Core.Compiler.visit_conditional_successors(CC.LazyPostDomtree(ir), ir, #=bb=#1) do succ::Int push!(visited, succ) return false end @test 2 ∈ visited @test 3 ∈ visited end Test Passed ``` This needs some tests (esp. since I don't think we have any DomTree tests at all right now), but otherwise should be good to go.
Seelengrab
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Apr 6, 2024
…iaLang#53642) This commit fixes the first problem that was found while digging into JuliaLang#53613. It turns out that the post-domtree constructed from regular `IRCode` doesn't work for visiting conditional successors for post-opt analysis in cases like: ```julia julia> let code = Any[ # block 1 GotoIfNot(Argument(2), 3), # block 2 ReturnNode(Argument(3)), # block 3 (we should visit this block) Expr(:call, throw, "potential throw"), ReturnNode(), # unreachable ] ir = make_ircode(code; slottypes=Any[Any,Bool,Bool]) visited = BitSet() @test !Core.Compiler.visit_conditional_successors(CC.LazyPostDomtree(ir), ir, #=bb=#1) do succ::Int push!(visited, succ) return false end @test 2 ∉ visited @test 3 ∈ visited end Test Failed at REPL[14]:16 Expression: 2 ∉ visited Evaluated: 2 ∉ BitSet([2]) ``` This might mean that we need to fix on the `postdominates` end, but for now, this commit tries to get around it by using the augmented post domtree in `visit_conditional_successors`. Since the augmented post domtree is enforced to have a single return, we can keep using the current `postdominates` to fix the issue. However, this commit isn't enough to fix the NeuralNetworkReachability segfault as reported in JuliaLang#53613, and we need to tackle the second issue reported there too (JuliaLang#53613 (comment)).
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This is an example request for a new, awesome feature! Here is a full description, perfectly specced out, ready to implement:
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