[clang] 7aa1fa0 - Reland "[dwarf] Emit a DIGlobalVariable for constant strings."
David Blaikie via cfe-commits
cfe-commits at lists.llvm.org
Mon May 23 14:14:10 PDT 2022
(when recommitting a patch it can be helpful to mention the revisions
of the previous commit/revert, the reason for the revert and what's
different in this version of the patch that addresses that issue (or
how was the issue otherwise addressed))
On Wed, May 18, 2022 at 1:59 PM Mitch Phillips via cfe-commits
<cfe-commits at lists.llvm.org> wrote:
>
>
> Author: Mitch Phillips
> Date: 2022-05-18T13:56:45-07:00
> New Revision: 7aa1fa0a0a07f7949d2d77c099aab43cf9b75a91
>
> URL: https://github.com/llvm/llvm-project/commit/7aa1fa0a0a07f7949d2d77c099aab43cf9b75a91
> DIFF: https://github.com/llvm/llvm-project/commit/7aa1fa0a0a07f7949d2d77c099aab43cf9b75a91.diff
>
> LOG: Reland "[dwarf] Emit a DIGlobalVariable for constant strings."
>
> An upcoming patch will extend llvm-symbolizer to provide the source line
> information for global variables. The goal is to move AddressSanitizer
> off of internal debug info for symbolization onto the DWARF standard
> (and doing a clean-up in the process). Currently, ASan reports the line
> information for constant strings if a memory safety bug happens around
> them. We want to keep this behaviour, so we need to emit debuginfo for
> these variables as well.
>
> Reviewed By: dblaikie, rnk, aprantl
>
> Differential Revision: https://reviews.llvm.org/D123534
>
> Added:
> clang/test/CodeGen/debug-info-variables.c
> llvm/test/DebugInfo/COFF/global-no-strings.ll
>
> Modified:
> clang/lib/CodeGen/CGDebugInfo.cpp
> clang/lib/CodeGen/CGDebugInfo.h
> clang/lib/CodeGen/CodeGenModule.cpp
> clang/test/VFS/external-names.c
> llvm/lib/AsmParser/LLParser.cpp
> llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
> llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
>
> Removed:
> llvm/test/Assembler/invalid-diglobalvariable-missing-name.ll
>
>
> ################################################################################
> diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
> index 3d73bfb8ce79..753427029441 100644
> --- a/clang/lib/CodeGen/CGDebugInfo.cpp
> +++ b/clang/lib/CodeGen/CGDebugInfo.cpp
> @@ -5132,7 +5132,7 @@ std::string CGDebugInfo::GetName(const Decl *D, bool Qualified) const {
> return Name;
> codegenoptions::DebugTemplateNamesKind TemplateNamesKind =
> CGM.getCodeGenOpts().getDebugSimpleTemplateNames();
> -
> +
> if (!CGM.getCodeGenOpts().hasReducedDebugInfo())
> TemplateNamesKind = codegenoptions::DebugTemplateNamesKind::Full;
>
> @@ -5459,6 +5459,21 @@ void CGDebugInfo::EmitGlobalAlias(const llvm::GlobalValue *GV,
> ImportedDeclCache[GD.getCanonicalDecl().getDecl()].reset(ImportDI);
> }
>
> +void CGDebugInfo::AddStringLiteralDebugInfo(llvm::GlobalVariable *GV,
> + const StringLiteral *S) {
> + SourceLocation Loc = S->getStrTokenLoc(0);
> + PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
> + if (!PLoc.isValid())
> + return;
> +
> + llvm::DIFile *File = getOrCreateFile(Loc);
> + llvm::DIGlobalVariableExpression *Debug =
> + DBuilder.createGlobalVariableExpression(
> + nullptr, StringRef(), StringRef(), getOrCreateFile(Loc),
> + getLineNumber(Loc), getOrCreateType(S->getType(), File), true);
> + GV->addDebugInfo(Debug);
> +}
> +
> llvm::DIScope *CGDebugInfo::getCurrentContextDescriptor(const Decl *D) {
> if (!LexicalBlockStack.empty())
> return LexicalBlockStack.back();
>
> diff --git a/clang/lib/CodeGen/CGDebugInfo.h b/clang/lib/CodeGen/CGDebugInfo.h
> index 8984f3eb1d7a..38e3fa5b2fa9 100644
> --- a/clang/lib/CodeGen/CGDebugInfo.h
> +++ b/clang/lib/CodeGen/CGDebugInfo.h
> @@ -533,6 +533,14 @@ class CGDebugInfo {
> /// Emit an @import declaration.
> void EmitImportDecl(const ImportDecl &ID);
>
> + /// DebugInfo isn't attached to string literals by default. While certain
> + /// aspects of debuginfo aren't useful for string literals (like a name), it's
> + /// nice to be able to symbolize the line and column information. This is
> + /// especially useful for sanitizers, as it allows symbolization of
> + /// heap-buffer-overflows on constant strings.
> + void AddStringLiteralDebugInfo(llvm::GlobalVariable *GV,
> + const StringLiteral *S);
> +
> /// Emit C++ namespace alias.
> llvm::DIImportedEntity *EmitNamespaceAlias(const NamespaceAliasDecl &NA);
>
>
> diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
> index f8bf210dc0e2..703cf4edf5f5 100644
> --- a/clang/lib/CodeGen/CodeGenModule.cpp
> +++ b/clang/lib/CodeGen/CodeGenModule.cpp
> @@ -5670,6 +5670,11 @@ CodeGenModule::GetAddrOfConstantStringFromLiteral(const StringLiteral *S,
> }
>
> auto GV = GenerateStringLiteral(C, LT, *this, GlobalVariableName, Alignment);
> +
> + CGDebugInfo *DI = getModuleDebugInfo();
> + if (DI && getCodeGenOpts().hasReducedDebugInfo())
> + DI->AddStringLiteralDebugInfo(GV, S);
> +
> if (Entry)
> *Entry = GV;
>
>
> diff --git a/clang/test/CodeGen/debug-info-variables.c b/clang/test/CodeGen/debug-info-variables.c
> new file mode 100644
> index 000000000000..8ec60ff7c1d9
> --- /dev/null
> +++ b/clang/test/CodeGen/debug-info-variables.c
> @@ -0,0 +1,20 @@
> +// RUN: %clang_cc1 %s -debug-info-kind=standalone -S -emit-llvm -o - | FileCheck %s
> +
> +// CHECK: DIGlobalVariable(name: "global",{{.*}} line: [[@LINE+1]]
> +int global = 42;
> +
> +// CHECK: DIGlobalVariable({{.*}}line: [[@LINE+4]],{{.*}} type: [[TYPEID:![0-9]+]]
> +// CHECK: [[TYPEID]] = !DICompositeType(tag: DW_TAG_array_type, baseType: [[BASETYPE:![0-9]+]]
> +// CHECK: [[BASETYPE]] = !DIBasicType(name: "char"
> +const char* s() {
> + return "1234567890";
> +}
> +
> +// Note: Windows has `q -> p -> r` ordering and Linux has `p -> q -> r`.
> +// CHECK-DAG: DILocalVariable(name: "p"
> +// CHECK-DAG: DILocalVariable(name: "q"
> +// CHECK-DAG: DILocalVariable(name: "r"
> +int sum(int p, int q) {
> + int r = p + q;
> + return r;
> +}
>
> diff --git a/clang/test/VFS/external-names.c b/clang/test/VFS/external-names.c
> index c50d240a32eb..964b174ee57e 100644
> --- a/clang/test/VFS/external-names.c
> +++ b/clang/test/VFS/external-names.c
> @@ -30,8 +30,8 @@
> // Debug info
>
> // RUN: %clang_cc1 -I %t -ivfsoverlay %t.external.yaml -triple %itanium_abi_triple -debug-info-kind=limited -emit-llvm %s -o - | FileCheck -check-prefix=CHECK-DEBUG-EXTERNAL %s
> -// CHECK-DEBUG-EXTERNAL: !DISubprogram({{.*}}file: ![[Num:[0-9]+]]
> -// CHECK-DEBUG-EXTERNAL: ![[Num]] = !DIFile(filename: "{{[^"]*}}Inputs{{..?}}external-names.h"
> +// CHECK-DEBUG-EXTERNAL: ![[Num:[0-9]+]] = !DIFile(filename: "{{[^"]*}}Inputs{{..?}}external-names.h"
> +// CHECK-DEBUG-EXTERNAL: !DISubprogram({{.*}}file: ![[Num]]
>
> // RUN: %clang_cc1 -I %t -ivfsoverlay %t.yaml -triple %itanium_abi_triple -debug-info-kind=limited -emit-llvm %s -o - | FileCheck -check-prefix=CHECK-DEBUG %s
> // CHECK-DEBUG-NOT: Inputs
>
> diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
> index d6d8743e13f3..5076c0bff44d 100644
> --- a/llvm/lib/AsmParser/LLParser.cpp
> +++ b/llvm/lib/AsmParser/LLParser.cpp
> @@ -5012,7 +5012,7 @@ bool LLParser::parseDITemplateValueParameter(MDNode *&Result, bool IsDistinct) {
> /// declaration: !4, align: 8)
> bool LLParser::parseDIGlobalVariable(MDNode *&Result, bool IsDistinct) {
> #define VISIT_MD_FIELDS(OPTIONAL, REQUIRED) \
> - REQUIRED(name, MDStringField, (/* AllowEmpty */ false)); \
> + OPTIONAL(name, MDStringField, (/* AllowEmpty */ false)); \
> OPTIONAL(scope, MDField, ); \
> OPTIONAL(linkageName, MDStringField, ); \
> OPTIONAL(file, MDField, ); \
>
> diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
> index 83d77cbeeac6..ece4167c791c 100644
> --- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
> +++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
> @@ -3175,6 +3175,11 @@ void CodeViewDebug::collectGlobalVariableInfo() {
> for (const auto *GVE : CU->getGlobalVariables()) {
> const DIGlobalVariable *DIGV = GVE->getVariable();
> const DIExpression *DIE = GVE->getExpression();
> + // Don't emit string literals in CodeView, as the only useful parts are
> + // generally the filename and line number, which isn't possible to output
> + // in CodeView. String literals should be the only unnamed GlobalVariable
> + // with debug info.
> + if (DIGV->getName().empty()) continue;
>
> if ((DIE->getNumElements() == 2) &&
> (DIE->getElement(0) == dwarf::DW_OP_plus_uconst))
>
> diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
> index 06fd724b2197..b2095ae5d11d 100644
> --- a/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
> +++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
> @@ -165,7 +165,9 @@ DIE *DwarfCompileUnit::getOrCreateGlobalVariableDIE(
> } else {
> DeclContext = GV->getScope();
> // Add name and type.
> - addString(*VariableDIE, dwarf::DW_AT_name, GV->getDisplayName());
> + StringRef DisplayName = GV->getDisplayName();
> + if (!DisplayName.empty())
> + addString(*VariableDIE, dwarf::DW_AT_name, GV->getDisplayName());
> if (GTy)
> addType(*VariableDIE, GTy);
>
>
> diff --git a/llvm/test/Assembler/invalid-diglobalvariable-missing-name.ll b/llvm/test/Assembler/invalid-diglobalvariable-missing-name.ll
> deleted file mode 100644
> index baf4d73d94f4..000000000000
> --- a/llvm/test/Assembler/invalid-diglobalvariable-missing-name.ll
> +++ /dev/null
> @@ -1,4 +0,0 @@
> -; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
> -
> -; CHECK: <stdin>:[[@LINE+1]]:24: error: missing required field 'name'
> -!0 = !DIGlobalVariable()
>
> diff --git a/llvm/test/DebugInfo/COFF/global-no-strings.ll b/llvm/test/DebugInfo/COFF/global-no-strings.ll
> new file mode 100644
> index 000000000000..bc3a3a11dd13
> --- /dev/null
> +++ b/llvm/test/DebugInfo/COFF/global-no-strings.ll
> @@ -0,0 +1,59 @@
> +; RUN: llc < %s | FileCheck %s
> +; RUN: llc < %s -filetype=obj | llvm-readobj - --codeview | FileCheck %s
> +
> +; This test ensures that no debuginfo is emitted for the constant "123456789"
> +; string. These global variables have debug expressions because DWARF has the
> +; ability to tie them to a file name and line number, but this isn't possible
> +; in CodeView, so we make sure it's omitted to save file size.
> +;
> +; The various CodeView outputs should have a description of "my_string", but not
> +; the string contents itself.
> +
> +; C++ source to regenerate:
> +; $ cat a.cpp
> +; char* my_string =
> +; "12345679";
> +;
> +; $ clang-cl a.cpp /GS- /Z7 /GR- /clang:-S /clang:-emit-llvm
> +
> +; CHECK-NOT: S_LDATA
> +; CHECK: S_GDATA
> +; CHECK-NOT: S_LDATA
> +; CHECK-NOT: S_GDATA
> +
> +; ModuleID = '/tmp/a.c'
> +source_filename = "/tmp/a.c"
> +target datalayout = "e-m:w-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
> +target triple = "x86_64-pc-windows-msvc19.20.0"
> +
> +$"??_C at _08HCBFHPJA@12345679?$AA@" = comdat any
> +
> +@"??_C at _08HCBFHPJA@12345679?$AA@" = linkonce_odr dso_local unnamed_addr constant [9 x i8] c"12345679\00", comdat, align 1, !dbg !0
> + at my_string = dso_local global ptr @"??_C at _08HCBFHPJA@12345679?$AA@", align 8, !dbg !7
> +
> +!llvm.dbg.cu = !{!9}
> +!llvm.linker.options = !{!13, !14}
> +!llvm.module.flags = !{!15, !16, !17, !18, !19}
> +!llvm.ident = !{!20}
> +
> +!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
> +!1 = distinct !DIGlobalVariable(scope: null, file: !2, line: 2, type: !3, isLocal: true, isDefinition: true)
> +!2 = !DIFile(filename: "/tmp/a.c", directory: "", checksumkind: CSK_MD5, checksum: "b972961d64de3c90497767110ab58eb6")
> +!3 = !DICompositeType(tag: DW_TAG_array_type, baseType: !4, size: 72, elements: !5)
> +!4 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_signed_char)
> +!5 = !{!6}
> +!6 = !DISubrange(count: 9)
> +!7 = !DIGlobalVariableExpression(var: !8, expr: !DIExpression())
> +!8 = distinct !DIGlobalVariable(name: "my_string", scope: !9, file: !2, line: 1, type: !12, isLocal: false, isDefinition: true)
> +!9 = distinct !DICompileUnit(language: DW_LANG_C99, file: !10, producer: "clang version 15.0.0 (https://github.com/llvm/llvm-project.git 7c1c0849f8a1a6f1bf5f5b554484bbf8b0debd0a)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, globals: !11, splitDebugInlining: false, nameTableKind: None)
> +!10 = !DIFile(filename: "/tmp/a.c", directory: "/usr/local/google/home/mitchp/llvm-build/opt", checksumkind: CSK_MD5, checksum: "b972961d64de3c90497767110ab58eb6")
> +!11 = !{!0, !7}
> +!12 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !4, size: 64)
> +!13 = !{!"/DEFAULTLIB:libcmt.lib"}
> +!14 = !{!"/DEFAULTLIB:oldnames.lib"}
> +!15 = !{i32 2, !"CodeView", i32 1}
> +!16 = !{i32 2, !"Debug Info Version", i32 3}
> +!17 = !{i32 1, !"wchar_size", i32 2}
> +!18 = !{i32 7, !"PIC Level", i32 2}
> +!19 = !{i32 7, !"uwtable", i32 2}
> +!20 = !{!"clang version 15.0.0 (https://github.com/llvm/llvm-project.git 7c1c0849f8a1a6f1bf5f5b554484bbf8b0debd0a)"}
>
>
>
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