--- /dev/null
+; RUN: llc -filetype=obj %s -o - | llvm-dwarfdump - | FileCheck %s
+
+; Test that byval args get correct DWARF debug locations.
+; These end up in the callee as Wasm locals, which is atypical.
+
+; From C code:
+
+; typedef union { int x; float y; } u;
+; typedef struct { int x; float y; } s;
+; int some_func(int x, u some_union, s some_struct, int a[3]) {
+; return x + some_union.x + some_struct.x + a[0];
+; }
+
+
+; ModuleID = 't.c'
+source_filename = "t.c"
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+%union.u = type { i32 }
+%struct.s = type { i32, float }
+
+; Function Attrs: noinline nounwind optnone
+define hidden i32 @some_func(i32 %x, %union.u* byval(%union.u) align 4 %some_union, %struct.s* byval(%struct.s) align 4 %some_struct, i32* %a) #0 !dbg !7 {
+entry:
+ %x.addr = alloca i32, align 4
+ %a.addr = alloca i32*, align 4
+ store i32 %x, i32* %x.addr, align 4
+ call void @llvm.dbg.declare(metadata i32* %x.addr, metadata !23, metadata !DIExpression()), !dbg !24
+ call void @llvm.dbg.declare(metadata %union.u* %some_union, metadata !25, metadata !DIExpression()), !dbg !26
+ call void @llvm.dbg.declare(metadata %struct.s* %some_struct, metadata !27, metadata !DIExpression()), !dbg !28
+ store i32* %a, i32** %a.addr, align 4
+ call void @llvm.dbg.declare(metadata i32** %a.addr, metadata !29, metadata !DIExpression()), !dbg !30
+ %0 = load i32, i32* %x.addr, align 4, !dbg !31
+ %x1 = bitcast %union.u* %some_union to i32*, !dbg !32
+ %1 = load i32, i32* %x1, align 4, !dbg !32
+ %add = add nsw i32 %0, %1, !dbg !33
+ %x2 = getelementptr inbounds %struct.s, %struct.s* %some_struct, i32 0, i32 0, !dbg !34
+ %2 = load i32, i32* %x2, align 4, !dbg !34
+ %add3 = add nsw i32 %add, %2, !dbg !35
+ %3 = load i32*, i32** %a.addr, align 4, !dbg !36
+ %arrayidx = getelementptr inbounds i32, i32* %3, i32 0, !dbg !36
+ %4 = load i32, i32* %arrayidx, align 4, !dbg !36
+ %add4 = add nsw i32 %add3, %4, !dbg !37
+ ret i32 %add4, !dbg !38
+}
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
+
+attributes #0 = { noinline nounwind optnone "disable-tail-calls"="false" "frame-pointer"="none" "less-precise-fpmad"="false" "min-legal-vector-width"="0" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="generic" "unsafe-fp-math"="false" "use-soft-float"="false" }
+attributes #1 = { nofree nosync nounwind readnone speculatable willreturn }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 12.0.0 (https://github.com/llvm/llvm-project.git eccc734a69c0c012ae3160887b65a535b35ead3e)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, nameTableKind: None)
+!1 = !DIFile(filename: "t.c", directory: "C:\\src\\llvm")
+!2 = !{}
+!3 = !{i32 7, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"wchar_size", i32 4}
+!6 = !{!"clang version 12.0.0 (https://github.com/llvm/llvm-project.git eccc734a69c0c012ae3160887b65a535b35ead3e)"}
+!7 = distinct !DISubprogram(name: "some_func", scope: !1, file: !1, line: 11, type: !8, scopeLine: 11, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{!10, !10, !11, !17, !22}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DIDerivedType(tag: DW_TAG_typedef, name: "u", file: !1, line: 4, baseType: !12)
+!12 = distinct !DICompositeType(tag: DW_TAG_union_type, file: !1, line: 1, size: 32, elements: !13)
+!13 = !{!14, !15}
+!14 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !12, file: !1, line: 2, baseType: !10, size: 32)
+!15 = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: !12, file: !1, line: 3, baseType: !16, size: 32)
+!16 = !DIBasicType(name: "float", size: 32, encoding: DW_ATE_float)
+!17 = !DIDerivedType(tag: DW_TAG_typedef, name: "s", file: !1, line: 9, baseType: !18)
+!18 = distinct !DICompositeType(tag: DW_TAG_structure_type, file: !1, line: 6, size: 64, elements: !19)
+!19 = !{!20, !21}
+!20 = !DIDerivedType(tag: DW_TAG_member, name: "x", scope: !18, file: !1, line: 7, baseType: !10, size: 32)
+!21 = !DIDerivedType(tag: DW_TAG_member, name: "y", scope: !18, file: !1, line: 8, baseType: !16, size: 32, offset: 32)
+!22 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 32)
+!23 = !DILocalVariable(name: "x", arg: 1, scope: !7, file: !1, line: 11, type: !10)
+!24 = !DILocation(line: 11, column: 19, scope: !7)
+!25 = !DILocalVariable(name: "some_union", arg: 2, scope: !7, file: !1, line: 11, type: !11)
+!26 = !DILocation(line: 11, column: 24, scope: !7)
+!27 = !DILocalVariable(name: "some_struct", arg: 3, scope: !7, file: !1, line: 11, type: !17)
+!28 = !DILocation(line: 11, column: 38, scope: !7)
+!29 = !DILocalVariable(name: "a", arg: 4, scope: !7, file: !1, line: 11, type: !22)
+!30 = !DILocation(line: 11, column: 55, scope: !7)
+!31 = !DILocation(line: 12, column: 12, scope: !7)
+!32 = !DILocation(line: 12, column: 27, scope: !7)
+!33 = !DILocation(line: 12, column: 14, scope: !7)
+!34 = !DILocation(line: 12, column: 43, scope: !7)
+!35 = !DILocation(line: 12, column: 29, scope: !7)
+!36 = !DILocation(line: 12, column: 47, scope: !7)
+!37 = !DILocation(line: 12, column: 45, scope: !7)
+!38 = !DILocation(line: 12, column: 5, scope: !7)
+
+
+
+
+; CHECK-LABEL: DW_TAG_formal_parameter
+; CHECK-NEXT: DW_AT_location (DW_OP_fbreg +12)
+; CHECK-NEXT: DW_AT_name ("x")
+
+; CHECK-LABEL: DW_TAG_formal_parameter
+; CHECK-NEXT: DW_AT_location (DW_OP_WASM_location 0x0 0x1, DW_OP_stack_value)
+; CHECK-NEXT: DW_AT_name ("some_union")
+
+; CHECK-LABEL: DW_TAG_formal_parameter
+; CHECK-NEXT: DW_AT_location (DW_OP_WASM_location 0x0 0x2, DW_OP_stack_value)
+; CHECK-NEXT: DW_AT_name ("some_struct")
+
+; CHECK-LABEL: DW_TAG_formal_parameter
+; CHECK-NEXT: DW_AT_location (DW_OP_fbreg +8)
+; CHECK-NEXT: DW_AT_name ("a")
+