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[WebAssembly] Fixed byval args missing DWARF DW_AT_LOCATION 

A struct in C passed by value did not get debug information. Such values are currently
lowered to a Wasm local even in -O0 (not to an alloca like on other archs), which becomes
a Target Index operand (TI_LOCAL). The DWARF writing code was not emitting locations
in for TI's specifically if the location is a single range (not a list).

In addition, the ExplicitLocals pass which removes the ARGUMENT pseudo instructions did
not update the associated DBG_VALUEs, and couldn't even find these values since the code
assumed such instructions are adjacent, which is not the case here.

Also fixed asm printing of TIs needed by a test.

Differential Revision: https://reviews.llvm.org/D94140
This commit is contained in:
Wouter van Oortmerssen 2021-01-05 16:58:21 -08:00
parent c9122ddef5
commit 5c38ae36c5
8 changed files with 148 additions and 4 deletions
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6
lld/test/wasm/debuginfo.test
View File

@ -21,6 +21,7 @@ CHECK-NEXT: DW_AT_decl_line (3)
CHECK-NEXT: DW_AT_prototyped (true)
CHECK: DW_TAG_formal_parameter
CHECK-NEXT: DW_AT_location (DW_OP_WASM_location 0x0 0x0, DW_OP_stack_value)
CHECK-NEXT: DW_AT_name ("t")
CHECK-NEXT: DW_AT_decl_file ("/Users/yury/llvmwasm{{(/|\\)}}hi.c")
CHECK-NEXT: DW_AT_decl_line (3)
@ -45,7 +46,7 @@ CHECK-NEXT: DW_AT_name ("hi_foo.c")
CHECK: DW_TAG_variable
CHECK-NEXT: DW_AT_name ("y")
CHECK-NEXT: DW_AT_type (0x000000a7 "int[2]")
CHECK-NEXT: DW_AT_type (0x000000ac "int[2]")
CHECK-NEXT: DW_AT_external (true)
CHECK-NEXT: DW_AT_decl_file ("{{.*}}hi_foo.c")
CHECK-NEXT: DW_AT_decl_line (1)
@ -67,7 +68,7 @@ CHECK-NEXT: DW_AT_encoding (DW_ATE_unsigned)
CHECK: DW_TAG_variable
CHECK-NEXT: DW_AT_name ("z")
CHECK-NEXT: DW_AT_type (0x000000a7 "int[2]")
CHECK-NEXT: DW_AT_type (0x000000ac "int[2]")
CHECK-NEXT: DW_AT_external (true)
CHECK-NEXT: DW_AT_decl_file ("{{.*}}hi_foo.c")
CHECK-NEXT: DW_AT_decl_line (8)
@ -82,6 +83,7 @@ CHECK-NEXT: DW_AT_decl_file ("{{.*}}hi_foo.c")
CHECK-NEXT: DW_AT_decl_line (3)
CHECK: DW_TAG_formal_parameter
CHECK-NEXT: DW_AT_location (DW_OP_WASM_location 0x0 0x0, DW_OP_stack_value)
CHECK-NEXT: DW_AT_name ("p")
CHECK-NEXT: DW_AT_decl_file ("{{.*}}hi_foo.c")
CHECK-NEXT: DW_AT_decl_line (3)

2
llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
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@ -948,6 +948,8 @@ static bool emitDebugValueComment(const MachineInstr *MI, AsmPrinter &AP) {
} else if (MI->getDebugOperand(0).isTargetIndex()) {
auto Op = MI->getDebugOperand(0);
OS << "!target-index(" << Op.getIndex() << "," << Op.getOffset() << ")";
// NOTE: Want this comment at start of line, don't emit with AddComment.
AP.OutStreamer->emitRawComment(OS.str());
return true;
} else {
Register Reg;

7
llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
View File

@ -720,6 +720,13 @@ DIE *DwarfCompileUnit::constructVariableDIEImpl(const DbgVariable &DV,
addConstantFPValue(*VariableDie, DVal->getConstantFP());
} else if (DVal->isConstantInt()) {
addConstantValue(*VariableDie, DVal->getConstantInt(), DV.getType());
} else if (DVal->isTargetIndexLocation()) {
DIELoc *Loc = new (DIEValueAllocator) DIELoc;
DIEDwarfExpression DwarfExpr(*Asm, *this, *Loc);
const DIBasicType *BT = dyn_cast<DIBasicType>(
static_cast<const Metadata *>(DV.getVariable()->getType()));
DwarfDebug::emitDebugLocValue(*Asm, BT, *DVal, DwarfExpr);
addBlock(*VariableDie, dwarf::DW_AT_location, DwarfExpr.finalize());
}
return VariableDie;
}

1
llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
View File

@ -2489,6 +2489,7 @@ void DwarfDebug::emitDebugLocValue(const AsmPrinter &AP, const DIBasicType *BT,
TargetIndexLocation Loc = Value.getTargetIndexLocation();
// TODO TargetIndexLocation is a target-independent. Currently only the WebAssembly-specific
// encoding is supported.
assert(AP.TM.getTargetTriple().isWasm());
DwarfExpr.addWasmLocation(Loc.Index, static_cast<uint64_t>(Loc.Offset));
DwarfExpr.addExpression(std::move(ExprCursor));
return;

14
llvm/lib/Target/WebAssembly/WebAssemblyDebugValueManager.cpp
View File

@ -20,7 +20,19 @@ using namespace llvm;
WebAssemblyDebugValueManager::WebAssemblyDebugValueManager(
MachineInstr *Instr) {
Instr->collectDebugValues(DbgValues);
// This code differs from MachineInstr::collectDebugValues in that it scans
// the whole BB, not just contiguous DBG_VALUEs.
if (!Instr->getOperand(0).isReg())
return;
MachineBasicBlock::iterator DI = *Instr;
++DI;
for (MachineBasicBlock::iterator DE = Instr->getParent()->end(); DI != DE;
++DI) {
if (DI->isDebugValue() &&
DI->getDebugOperandForReg(Instr->getOperand(0).getReg()))
DbgValues.push_back(&*DI);
}
}
void WebAssemblyDebugValueManager::move(MachineInstr *Insert) {

4
llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
View File

@ -241,6 +241,10 @@ bool WebAssemblyExplicitLocals::runOnMachineFunction(MachineFunction &MF) {
auto Local = static_cast<unsigned>(MI.getOperand(1).getImm());
Reg2Local[Reg] = Local;
checkFrameBase(MFI, Local, Reg);
// Update debug value to point to the local before removing.
WebAssemblyDebugValueManager(&MI).replaceWithLocal(Local);
MI.eraseFromParent();
Changed = true;
}

2
llvm/test/CodeGen/WebAssembly/dbgvalue.ll
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@ -1,7 +1,7 @@
; RUN: llc < %s -O0 -verify-machineinstrs | FileCheck %s
; CHECK: %bb.0
; CHECK: #DEBUG_VALUE: usage:self <- %4
; CHECK: #DEBUG_VALUE: usage:self <- !target-index(0,0)
; CHECK: %bb.1
; CHECK: DW_TAG_variable
source_filename = "test/CodeGen/WebAssembly/dbgvalue.ll"

116
llvm/test/MC/WebAssembly/debug-byval-struct.ll Normal file
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@ -0,0 +1,116 @@
; 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")