Repeated savepoints on higher order AD

[wsmoses]

using Enzyme

function d(f)
    return x -> (autodiff(Forward, Const(f), Duplicated(x, 1.0))[1])
end

@show sin(2.0)
@show d(sin)(2.0)
@show d(d(sin))(2.0)
@show d(d(d(sin)))(2.0)
@show d(d(d(d(sin))))(2.0)
@show d(d(d(d(d(sin)))))(2.0)
@show d(d(d(d(d(d(sin))))))(2.0)

Enzyme.API.printall!(true)
@show d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(sin)))))))))))))))(2.0)

; Function Attrs: mustprogress nofree
define internal double @fwddiffejulia__11_2152(double "enzyme_type"="{[-1]:Float@double}" "enzymejl_parmtype"="5251946832" "enzymejl_parmtype_ref"="0" %0, double "enzyme_type"="{[-1]:Float@double}" "enzymejl_parmtype"="5251946832" "enzymejl_parmtype_ref"="0" %"'") local_unnamed_addr #5 !dbg !1054 {
top:
  %1 = call {}*** @julia.get_pgcstack() #6
  %ptls_field3 = getelementptr inbounds {}**, {}*** %1, i64 2
  %2 = bitcast {}*** %ptls_field3 to i64***
  %ptls_load45 = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1055, !noalias !1058
  %3 = getelementptr inbounds i64*, i64** %ptls_load45, i64 2
  %safepoint = load i64*, i64** %3, align 8, !tbaa !28, !alias.scope !1060, !noalias !1063
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint) #6, !dbg !1065
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1066, !noalias !1067
  %4 = getelementptr inbounds i64*, i64** %ptls_load45.i.i, i64 2
  %safepoint.i.i = load i64*, i64** %4, align 8, !tbaa !28, !alias.scope !1068, !noalias !1071
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i) #6, !dbg !1073
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1080, !noalias !1081
  %5 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i, i64 2
  %safepoint.i.i.i.i = load i64*, i64** %5, align 8, !tbaa !28, !alias.scope !1082, !noalias !1085
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i) #6, !dbg !1087
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1095, !noalias !1096
  %6 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i = load i64*, i64** %6, align 8, !tbaa !28, !alias.scope !1097, !noalias !1100
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i) #6, !dbg !1102
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1110, !noalias !1111
  %7 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i = load i64*, i64** %7, align 8, !tbaa !28, !alias.scope !1112, !noalias !1115
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i) #6, !dbg !1117
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1125, !noalias !1126
  %8 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %8, align 8, !tbaa !28, !alias.scope !1127, !noalias !1130
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1132
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1140, !noalias !1141
  %9 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %9, align 8, !tbaa !28, !alias.scope !1142, !noalias !1145
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1147
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1155, !noalias !1156
  %10 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %10, align 8, !tbaa !28, !alias.scope !1157, !noalias !1160
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1162
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1170, !noalias !1171
  %11 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %11, align 8, !tbaa !28, !alias.scope !1172, !noalias !1175
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1177
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1185, !noalias !1186
  %12 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %12, align 8, !tbaa !28, !alias.scope !1187, !noalias !1190
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1192
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1200, !noalias !1201
  %13 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %13, align 8, !tbaa !28, !alias.scope !1202, !noalias !1205
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1207
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1215, !noalias !1216
  %14 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %14, align 8, !tbaa !28, !alias.scope !1217, !noalias !1220
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1222
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1230, !noalias !1231
  %15 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %15, align 8, !tbaa !28, !alias.scope !1232, !noalias !1235
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1237
  fence syncscope("singlethread") seq_cst
  %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64**, i64*** %2, align 8, !tbaa !24, !alias.scope !1245, !noalias !1246
  %16 = getelementptr inbounds i64*, i64** %ptls_load45.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i, i64 2
  %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i = load i64*, i64** %16, align 8, !tbaa !28, !alias.scope !1247, !noalias !1250
  fence syncscope("singlethread") seq_cst
  call void @julia.safepoint(i64* %safepoint.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i.i) #6, !dbg !1252
  fence syncscope("singlethread") seq_cst
  %17 = call fast double @llvm.cos.f64(double %0), !dbg !1260
  %18 = fmul fast double %"'", %17, !dbg !1260
  %19 = fneg fast double %18, !dbg !1261
  ret double %19
}

(d(d(d(d(d(d(d(d(d(d(d(d(d(d(d(sin))))))))))))))))(2.0) = 0.4161468365471424
0.4161468365471424

[wsmoses]

my guess as to why this is happening is because inlining won't delete the savepoint [which it ought be possible to do]