Name LLVM function arguments #50500

pchintalapudi · 2023-07-11T00:31:33Z

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.

Example 1

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)

;  @ 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"() #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
}

Example 2

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)

;  @ 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
}

gbaraldi · 2023-07-11T01:20:08Z

LGTM, I was thinking about this today, the result seems very cool.

pchintalapudi · 2023-07-11T02:11:52Z

I guess the next question is if we want this enabled always or just when running with -g2

Seelengrab · 2023-07-11T05:33:46Z

i64 signext %"g[0]::Int64"

That looks a bit odd, considering our indexing usually starts at 1.

Seelengrab · 2023-07-11T16:33:54Z

i64 signext %"g[0]::Int64"

Another thought - since this is (presumably) always from slurping, we don't have to worry about offset arrays here, right?

pchintalapudi · 2023-07-11T17:14:19Z

These indexes are fake anyways, by the time we're making up LLVM argument names for varargs they're already individual LLVM arguments. The index is just for pretty presentation rather than ...1, ...2, etc.

src/codegen.cpp

vtjnash · 2023-07-11T17:40:42Z

src/codegen.cpp

        f = cast<Function>(returninfo.decl.getCallee());
        has_sret = (returninfo.cc == jl_returninfo_t::SRet || returninfo.cc == jl_returninfo_t::Union);
        jl_init_function(f, ctx.emission_context.TargetTriple);
+        auto arg_typename = [&](size_t i) JL_NOTSAFEPOINT { return jl_symbol_name(((jl_datatype_t*)jl_tparam(lam->specTypes, i))->name->name); };


Not safe to cast this to a datatype.

vtjnash

What is the overhead of doing this?

pchintalapudi · 2023-07-11T20:49:05Z

Probably not great for functions with large numbers of arguments, so it might be better to stick it behind -g1 and force debug info emission with code_llvm.

vtjnash · 2023-07-12T15:04:19Z

src/codegen.cpp

+        if (ctx.emission_context.debug_level > 0) {
+            auto arg_typename = [&](size_t i) JL_NOTSAFEPOINT {
+                auto tp = jl_tparam(lam->specTypes, i);
+                return jl_is_datatype(tp) ? jl_symbol_name(((jl_datatype_t*)tp)->name->name) : "<unknown datatype>";


Suggested change

return jl_is_datatype(tp) ? jl_symbol_name(((jl_datatype_t*)tp)->name->name) : "<unknown datatype>";

return jl_is_datatype(tp) ? jl_symbol_name(((jl_datatype_t*)tp)->name->name) : "<unknown datatype>";

But it isn't a datatype, so why does it say "unknown datatype"

Can we mark it as unknown type or ::Any then?

Name LLVM function arguments

39aff78

pchintalapudi added the compiler:llvm For issues that relate to LLVM label Jul 11, 2023

pchintalapudi requested review from vchuravy, maleadt and gbaraldi July 11, 2023 00:31

Fix some test issues

cab1fe3

Minor fixes

39638cf

pchintalapudi commented Jul 11, 2023

View reviewed changes

src/codegen.cpp Outdated Show resolved Hide resolved

vtjnash reviewed Jul 11, 2023

View reviewed changes

Address review comments

9f62658

vtjnash reviewed Jul 12, 2023

View reviewed changes

Couple of extra comments

2984f9c

pchintalapudi added this pull request to the merge queue Jul 15, 2023

Merged via the queue into master with commit 7735556 Jul 15, 2023
1 check passed

pchintalapudi deleted the pc/arg-names branch July 15, 2023 15:36

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Name LLVM function arguments #50500

Name LLVM function arguments #50500

pchintalapudi commented Jul 11, 2023

gbaraldi commented Jul 11, 2023

pchintalapudi commented Jul 11, 2023

Seelengrab commented Jul 11, 2023 •

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pchintalapudi commented Jul 11, 2023

vtjnash Jul 11, 2023

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pchintalapudi commented Jul 11, 2023

vtjnash Jul 12, 2023

pchintalapudi Jul 12, 2023

	return jl_is_datatype(tp) ? jl_symbol_name(((jl_datatype_t*)tp)->name->name) : "<unknown datatype>";
	return jl_is_datatype(tp) ? jl_symbol_name(((jl_datatype_t*)tp)->name->name) : "<unknown datatype>";

Name LLVM function arguments #50500

Name LLVM function arguments #50500

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