[llvm-branch-commits] [lld] 5c38ae3 - [WebAssembly] Fixed byval args missing DWARF DW_AT_LOCATION

Wouter van Oortmerssen via llvm-branch-commits llvm-branch-commits at lists.llvm.org
Thu Jan 7 10:37:29 PST 2021


Author: Wouter van Oortmerssen
Date: 2021-01-07T10:31:38-08:00
New Revision: 5c38ae36c58f5b6bb4a32e9ec2187fde86cf94b8

URL: https://github.com/llvm/llvm-project/commit/5c38ae36c58f5b6bb4a32e9ec2187fde86cf94b8
DIFF: https://github.com/llvm/llvm-project/commit/5c38ae36c58f5b6bb4a32e9ec2187fde86cf94b8.diff

LOG: [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

Added: 
    llvm/test/MC/WebAssembly/debug-byval-struct.ll

Modified: 
    lld/test/wasm/debuginfo.test
    llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
    llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
    llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
    llvm/lib/Target/WebAssembly/WebAssemblyDebugValueManager.cpp
    llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
    llvm/test/CodeGen/WebAssembly/dbgvalue.ll

Removed: 
    


################################################################################
diff  --git a/lld/test/wasm/debuginfo.test b/lld/test/wasm/debuginfo.test
index 94d183a3c1d4..9cb1cc31e515 100644
--- a/lld/test/wasm/debuginfo.test
+++ b/lld/test/wasm/debuginfo.test
@@ -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)

diff  --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 85a5d0c59b83..d72a91825061 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -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;

diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
index ea279e4914b0..befc4bba19a2 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -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;
   }

diff  --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
index fa5d55071e17..12b62834d8ee 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -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;

diff  --git a/llvm/lib/Target/WebAssembly/WebAssemblyDebugValueManager.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyDebugValueManager.cpp
index 159fb4c00ddc..78191ae758fe 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyDebugValueManager.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyDebugValueManager.cpp
@@ -20,7 +20,19 @@ using namespace llvm;
 
 WebAssemblyDebugValueManager::WebAssemblyDebugValueManager(
     MachineInstr *Instr) {
-  Instr->collectDebugValues(DbgValues);
+  // This code 
diff ers 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) {

diff  --git a/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp b/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
index 2101676906ff..9014b8f9783a 100644
--- a/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
+++ b/llvm/lib/Target/WebAssembly/WebAssemblyExplicitLocals.cpp
@@ -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;
   }

diff  --git a/llvm/test/CodeGen/WebAssembly/dbgvalue.ll b/llvm/test/CodeGen/WebAssembly/dbgvalue.ll
index df64033ff7ec..6c9e5ef4a1af 100644
--- a/llvm/test/CodeGen/WebAssembly/dbgvalue.ll
+++ b/llvm/test/CodeGen/WebAssembly/dbgvalue.ll
@@ -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"

diff  --git a/llvm/test/MC/WebAssembly/debug-byval-struct.ll b/llvm/test/MC/WebAssembly/debug-byval-struct.ll
new file mode 100644
index 000000000000..9d90764a3708
--- /dev/null
+++ b/llvm/test/MC/WebAssembly/debug-byval-struct.ll
@@ -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")
+


        


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