[llvm] r317730 - Let replaceVTableHolder accept any type.
Yung, Douglas via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 9 20:47:20 PST 2017
Hi Adrian and Tom,
The test added in this commit, llvm/trunk/test/DebugInfo/Generic/containing-type-extension-rust.ll contains the following line:
target triple = "x86_64-unknown-linux-gnu"
This causes it to fail on compilers that do not include x86 as a target:
http://lab.llvm.org:8011/builders/clang-cmake-armv7-a15/builds/12905
Perhaps this test should be moved to the X86 directory?
Douglas Yung
> -----Original Message-----
> From: llvm-commits [mailto:llvm-commits-bounces at lists.llvm.org] On Behalf Of
> Adrian Prantl via llvm-commits
> Sent: Wednesday, November 08, 2017 14:05
> To: llvm-commits at lists.llvm.org
> Subject: [llvm] r317730 - Let replaceVTableHolder accept any type.
>
> Author: adrian
> Date: Wed Nov 8 14:04:43 2017
> New Revision: 317730
>
> URL: http://llvm.org/viewvc/llvm-project?rev=317730&view=rev
> Log:
> Let replaceVTableHolder accept any type.
>
> In Rust, a trait can be implemented for any type, and if a trait object
> pointer is used for the type, then a virtual table will be emitted for that
> trait/type combination.
>
> We would like debuggers to be able to inspect trait objects, which requires
> finding the concrete type associated with a given vtable.
>
> This patch changes LLVM so that any type can be passed to replaceVTableHolder.
> This allows the Rust compiler to emit the needed debug info -- associating a
> vtable with the concrete type for which it was emitted.
>
> This is a DWARF extension: DWARF only specifies the meaning of
> DW_AT_containing_type in one specific situation. This style of DWARF extension
> is routine, though, and LLVM already has one such case for
> DW_AT_containing_type.
>
> Patch by Tom Tromey!
>
> Differential Revision: https://reviews.llvm.org/D39503
>
> Added:
> llvm/trunk/test/DebugInfo/Generic/containing-type-extension-rust.ll
> llvm/trunk/test/DebugInfo/Generic/containing-type-extension.ll
> Modified:
> llvm/trunk/include/llvm/IR/DIBuilder.h
> llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
> llvm/trunk/lib/IR/DIBuilder.cpp
> llvm/trunk/unittests/IR/MetadataTest.cpp
>
> Modified: llvm/trunk/include/llvm/IR/DIBuilder.h
> URL: http://llvm.org/viewvc/llvm-
> project/llvm/trunk/include/llvm/IR/DIBuilder.h?rev=317730&r1=317729&r2=317730&
> view=diff
> ==============================================================================
> --- llvm/trunk/include/llvm/IR/DIBuilder.h (original)
> +++ llvm/trunk/include/llvm/IR/DIBuilder.h Wed Nov 8 14:04:43 2017
> @@ -757,12 +757,12 @@ namespace llvm {
> const DILocation *DL,
> Instruction *InsertBefore);
>
> - /// Replace the vtable holder in the given composite type.
> + /// Replace the vtable holder in the given type.
> ///
> /// If this creates a self reference, it may orphan some unresolved
> cycles
> /// in the operands of \c T, so \a DIBuilder needs to track that.
> void replaceVTableHolder(DICompositeType *&T,
> - DICompositeType *VTableHolder);
> + DIType *VTableHolder);
>
> /// Replace arrays on a composite type.
> ///
>
> Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
> URL: http://llvm.org/viewvc/llvm-
> project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=317730&r1=317729&r
> 2=317730&view=diff
> ==============================================================================
> --- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
> +++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Wed Nov 8 14:04:43
> +++ 2017
> @@ -960,8 +960,9 @@ void DwarfUnit::constructTypeDIE(DIE &Bu
>
> // This is outside the DWARF spec, but GDB expects a
> DW_AT_containing_type
> // inside C++ composite types to point to the base class with the vtable.
> - if (auto *ContainingType =
> - dyn_cast_or_null<DICompositeType>(resolve(CTy-
> >getVTableHolder())))
> + // Rust uses DW_AT_containing_type to link a vtable to the type
> + // for which it was created.
> + if (auto *ContainingType = resolve(CTy->getVTableHolder()))
> addDIEEntry(Buffer, dwarf::DW_AT_containing_type,
> *getOrCreateTypeDIE(ContainingType));
>
>
> Modified: llvm/trunk/lib/IR/DIBuilder.cpp
> URL: http://llvm.org/viewvc/llvm-
> project/llvm/trunk/lib/IR/DIBuilder.cpp?rev=317730&r1=317729&r2=317730&view=di
> ff
> ==============================================================================
> --- llvm/trunk/lib/IR/DIBuilder.cpp (original)
> +++ llvm/trunk/lib/IR/DIBuilder.cpp Wed Nov 8 14:04:43 2017
> @@ -874,7 +874,7 @@ Instruction *DIBuilder::insertDbgValueIn }
>
> void DIBuilder::replaceVTableHolder(DICompositeType *&T,
> - DICompositeType *VTableHolder) {
> + DIType *VTableHolder) {
> {
> TypedTrackingMDRef<DICompositeType> N(T);
> N->replaceVTableHolder(VTableHolder);
>
> Added: llvm/trunk/test/DebugInfo/Generic/containing-type-extension-rust.ll
> URL: http://llvm.org/viewvc/llvm-
> project/llvm/trunk/test/DebugInfo/Generic/containing-type-extension-
> rust.ll?rev=317730&view=auto
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/Generic/containing-type-extension-rust.ll
> (added)
> +++ llvm/trunk/test/DebugInfo/Generic/containing-type-extension-rust.ll
> +++ Wed Nov 8 14:04:43 2017
> @@ -0,0 +1,125 @@
> +; REQUIRES: object-emission
> +
> +; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t ; RUN: llvm-dwarfdump -v
> +-debug-info %t | FileCheck %s
> +
> +; Check that any type can have a vtable holder.
> +; CHECK: [[SP:.*]]: DW_TAG_structure_type ; CHECK-NOT: TAG ; CHECK:
> +DW_AT_containing_type [DW_FORM_ref4] ; CHECK: DW_AT_name [DW_FORM_strp]
> +{{.*}}= "vtable")
> +
> +; This was compiled using
> +; rustc -g --emit=llvm-ir t2.rs
> +; ... and then edited by hand, because rustc is using a somewhat older llvm.
> +;
> +; t2.rs is:
> +;
> +; // trait object test case
> +;
> +; pub trait T {
> +; }
> +;
> +; impl T for f64 {
> +; }
> +;
> +; pub fn main() {
> +; let tu = &23.0f64 as &T;
> +; }
> +; t2.rs ends here ^^^
> +
> +; ModuleID = 't2.cgu-0.rs'
> +source_filename = "t2.cgu-0.rs"
> +target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-unknown-linux-gnu"
> +
> + at ref.0 = internal unnamed_addr constant double 2.300000e+01, align 8
> + at vtable.1 = internal unnamed_addr constant { void (double*)*, i64, i64
> +} { void (double*)* @_ZN4core3ptr13drop_in_place17h2818a933abde117eE,
> +i64 8, i64 8 }, align 8, !dbg !0 @__rustc_debug_gdb_scripts_section__ =
> +linkonce_odr unnamed_addr constant [34 x i8]
> +c"\01gdb_load_rust_pretty_printers.py\00", section
> +".debug_gdb_scripts", align 1
> +
> +; core::ptr::drop_in_place
> +; Function Attrs: uwtable
> +define internal void
> + at _ZN4core3ptr13drop_in_place17h2818a933abde117eE(double*) unnamed_addr
> +#0 !dbg !11 {
> +start:
> + %arg0 = alloca double*
> + store double* %0, double** %arg0
> + call void @llvm.dbg.declare(metadata double** %arg0, metadata !20,
> +metadata !22), !dbg !23
> + ret void, !dbg !24
> +}
> +
> +; t2::main
> +; Function Attrs: uwtable
> +define internal void @_ZN2t24main17h6319e6ac7de3a097E() unnamed_addr #0
> +!dbg !25 {
> +start:
> + %tu = alloca { i8*, void (i8*)** }
> + call void @llvm.dbg.declare(metadata { i8*, void (i8*)** }* %tu,
> +metadata !29, metadata !22), !dbg !37
> + %0 = getelementptr inbounds { i8*, void (i8*)** }, { i8*, void
> +(i8*)** }* %tu, i32 0, i32 0, !dbg !37
> + store i8* bitcast (double* @ref.0 to i8*), i8** %0, !dbg !37
> + %1 = getelementptr inbounds { i8*, void (i8*)** }, { i8*, void
> +(i8*)** }* %tu, i32 0, i32 1, !dbg !37
> + store void (i8*)** bitcast ({ void (double*)*, i64, i64 }* @vtable.1
> +to void (i8*)**), void (i8*)*** %1, !dbg !37
> + ret void, !dbg !38
> +}
> +
> +; Function Attrs: nounwind readnone
> +declare void @llvm.dbg.declare(metadata, metadata, metadata) #1
> +
> +define i32 @main(i32, i8**) unnamed_addr #2 {
> +top:
> + %2 = load volatile i8, i8* getelementptr inbounds ([34 x i8], [34 x
> +i8]* @__rustc_debug_gdb_scripts_section__, i32 0, i32 0), align 1
> + %3 = sext i32 %0 to i64
> +; call std::rt::lang_start
> + %4 = call i64 @_ZN3std2rt10lang_start17h2626caf1112a00beE(void ()*
> + at _ZN2t24main17h6319e6ac7de3a097E, i64 %3, i8** %1)
> + %5 = trunc i64 %4 to i32
> + ret i32 %5
> +}
> +
> +; std::rt::lang_start
> +declare i64 @_ZN3std2rt10lang_start17h2626caf1112a00beE(void ()*, i64,
> +i8**) unnamed_addr #3
> +
> +attributes #0 = { uwtable "no-frame-pointer-elim"="true"
> +"probe-stack"="__rust_probestack" } attributes #1 = { nounwind readnone
> +} attributes #2 = { "no-frame-pointer-elim"="true" } attributes #3 = {
> +"no-frame-pointer-elim"="true" "probe-stack"="__rust_probestack" }
> +
> +!llvm.module.flags = !{!6, !7}
> +!llvm.dbg.cu = !{!8}
> +
> +!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
> +!1 = distinct !DIGlobalVariable(name: "vtable", scope: null, file: !2,
> +type: !3, isLocal: true, isDefinition: true)
> +!2 = !DIFile(filename: "<unknown>", directory: "")
> +!3 = !DICompositeType(tag: DW_TAG_structure_type, name: "vtable", file:
> +!2, size: 64, align: 64, flags: DIFlagArtificial, elements: !4,
> +vtableHolder: !5, identifier: "vtable")
> +!4 = !{}
> +!5 = !DIBasicType(name: "f64", size: 64, encoding: DW_ATE_float)
> +!6 = !{i32 1, !"PIE Level", i32 2}
> +!7 = !{i32 2, !"Debug Info Version", i32 3}
> +!8 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !9,
> +producer: "clang LLVM (rustc version 1.22.0-dev)", isOptimized: false,
> +runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !10)
> +!9 = !DIFile(filename: "t2.rs", directory: "/home/tromey/Rust")
> +!10 = !{!0}
> +!11 = distinct !DISubprogram(name: "drop_in_place<f64>", linkageName:
> +"_ZN4core3ptr18drop_in_place<f64>E", scope: !13, file: !12, line: 59,
> +type: !15, isLocal: false, isDefinition: true, scopeLine: 59, flags:
> +DIFlagPrototyped, isOptimized: false, unit: !8, templateParams: !18,
> +variables: !4)
> +!12 = !DIFile(filename: "/home/tromey/Rust/rust/src/libcore/ptr.rs",
> +directory: "")
> +!13 = !DINamespace(name: "ptr", scope: !14)
> +!14 = !DINamespace(name: "core", scope: null)
> +!15 = !DISubroutineType(types: !16)
> +!16 = !{null, !17}
> +!17 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*mut f64",
> +baseType: !5, size: 64, align: 64)
> +!18 = !{!19}
> +!19 = !DITemplateTypeParameter(name: "T", type: !5)
> +!20 = !DILocalVariable(arg: 1, scope: !11, file: !21, line: 1, type:
> +!17)
> +!21 = !DIFile(filename: "t2.rs", directory: "")
> +!22 = !DIExpression()
> +!23 = !DILocation(line: 1, scope: !11)
> +!24 = !DILocation(line: 59, scope: !11)
> +!25 = distinct !DISubprogram(name: "main", linkageName: "_ZN2t24mainE",
> +scope: !26, file: !9, line: 9, type: !27, isLocal: true, isDefinition:
> +true, scopeLine: 9, flags: DIFlagPrototyped | DIFlagMainSubprogram,
> +isOptimized: false, unit: !8, templateParams: !4, variables: !4)
> +!26 = !DINamespace(name: "t2", scope: null)
> +!27 = !DISubroutineType(types: !28)
> +!28 = !{null}
> +!29 = !DILocalVariable(name: "tu", scope: !30, file: !9, line: 10,
> +type: !31, align: 8)
> +!30 = distinct !DILexicalBlock(scope: !25, file: !9, line: 10, column:
> +4)
> +!31 = !DICompositeType(tag: DW_TAG_structure_type, name: "&T", scope:
> +!26, file: !2, size: 128, align: 64, elements: !32, identifier:
> +"b9f642b757d8ad3984c1e721e3ce6016d14d9322")
> +!32 = !{!33, !36}
> +!33 = !DIDerivedType(tag: DW_TAG_member, name: "pointer", scope: !31,
> +file: !2, baseType: !34, size: 64, align: 64, flags: DIFlagArtificial)
> +!34 = !DIDerivedType(tag: DW_TAG_pointer_type, name: "*const u8",
> +baseType: !35, size: 64, align: 64)
> +!35 = !DIBasicType(name: "u8", size: 8, encoding: DW_ATE_unsigned)
> +!36 = !DIDerivedType(tag: DW_TAG_member, name: "vtable", scope: !31,
> +file: !2, baseType: !34, size: 64, align: 64, offset: 64, flags:
> +DIFlagArtificial)
> +!37 = !DILocation(line: 10, scope: !30)
> +!38 = !DILocation(line: 11, scope: !25)
>
> Added: llvm/trunk/test/DebugInfo/Generic/containing-type-extension.ll
> URL: http://llvm.org/viewvc/llvm-
> project/llvm/trunk/test/DebugInfo/Generic/containing-type-
> extension.ll?rev=317730&view=auto
> ==============================================================================
> --- llvm/trunk/test/DebugInfo/Generic/containing-type-extension.ll (added)
> +++ llvm/trunk/test/DebugInfo/Generic/containing-type-extension.ll Wed
> +++ Nov 8 14:04:43 2017
> @@ -0,0 +1,39 @@
> +; REQUIRES: object-emission
> +
> +; RUN: %llc_dwarf -O0 -filetype=obj < %s > %t ; RUN: llvm-dwarfdump -v
> +-debug-info %t | FileCheck %s
> +
> +; Check that any type can have a vtable holder.
> +; CHECK: [[SP:.*]]: DW_TAG_structure_type ; CHECK-NOT: TAG ; CHECK:
> +DW_AT_containing_type [DW_FORM_ref4] ; CHECK: DW_AT_name [DW_FORM_strp]
> +{{.*}}= "vtable")
> +
> +; The code doesn't actually matter.
> +define i32 @main() #0 !dbg !4 {
> +entry:
> + %retval = alloca i32, align 4
> + store i32 0, i32* %retval
> + ret i32 0, !dbg !10
> +}
> +
> +attributes #0 = { nounwind uwtable }
> +
> +!llvm.dbg.cu = !{!0}
> +!llvm.module.flags = !{!9, !11}
> +
> +!0 = distinct !DICompileUnit(language: DW_LANG_Rust, producer: "clang
> +version 3.4 (trunk 185475)", isOptimized: false, emissionKind:
> +FullDebug, file: !1, enums: !2, retainedTypes: !2, globals: !15,
> +imports: !2)
> +!1 = !DIFile(filename: "CodeGen/dwarf-version.c", directory: "test")
> +!2 = !{}
> +!4 = distinct !DISubprogram(name: "main", line: 6, isLocal: false,
> +isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped |
> +DIFlagMainSubprogram, isOptimized: false, unit: !0, scopeLine: 6, file:
> +!1, scope: !5, type: !6, variables: !2)
> +!5 = !DIFile(filename: "CodeGen/dwarf-version.c", directory: "test")
> +!6 = !DISubroutineType(types: !7)
> +!7 = !{!8}
> +!8 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align:
> +32, encoding: DW_ATE_signed)
> +!9 = !{i32 2, !"Dwarf Version", i32 4}
> +!10 = !DILocation(line: 7, scope: !4)
> +!11 = !{i32 1, !"Debug Info Version", i32 3}
> +!12 = !DICompositeType(tag: DW_TAG_structure_type, name: "vtable",
> +size: 8, align: 8, elements: !2, identifier: "vtable", vtableHolder:
> +!8)
> +!13 = !DIGlobalVariableExpression(var: !14, expr: !DIExpression())
> +!14 = !DIGlobalVariable(name: "vtable", linkageName: "vtable", scope:
> +null, file: !1, line: 1, type: !12, isLocal: true, isDefinition: true)
> +!15 = !{!13}
>
> Modified: llvm/trunk/unittests/IR/MetadataTest.cpp
> URL: http://llvm.org/viewvc/llvm-
> project/llvm/trunk/unittests/IR/MetadataTest.cpp?rev=317730&r1=317729&r2=31773
> 0&view=diff
> ==============================================================================
> --- llvm/trunk/unittests/IR/MetadataTest.cpp (original)
> +++ llvm/trunk/unittests/IR/MetadataTest.cpp Wed Nov 8 14:04:43 2017
> @@ -1314,6 +1314,11 @@ TEST_F(DICompositeTypeTest, replaceOpera
> EXPECT_EQ(nullptr, N->getVTableHolder());
> N->replaceVTableHolder(VTableHolder);
> EXPECT_EQ(VTableHolder, N->getVTableHolder());
> + // As an extension, the containing type can be anything. This is //
> + used by Rust to associate vtables with their concrete type.
> + DIType *BasicType = getBasicType("basic");
> + N->replaceVTableHolder(BasicType);
> + EXPECT_EQ(BasicType, N->getVTableHolder());
> N->replaceVTableHolder(nullptr);
> EXPECT_EQ(nullptr, N->getVTableHolder());
>
>
>
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