[llvm] CodeGen: add a missing check for bit-slice overlap in CV (PR #75504)
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llvm-commits at lists.llvm.org
Thu Dec 14 09:53:07 PST 2023
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-debuginfo
Author: Saleem Abdulrasool (compnerd)
<details>
<summary>Changes</summary>
Type dereferenced fragments are specified by offset and length in bits. The representation in CodeView is defined in terms of byte offsets. If the bit slice overlaps at a byte that is included, we would create invalid definition ranges.
Consider the following scenario:
~~~
01234567 01234567
---------+---------
==== ======
~~~
Here bits 1-4 are marked as defined as well as bits 7-9. The byte range for the second portion overlaps and so we would say that bytes 1 and 2 are valid though there is potentially a hole. There is no way to represent this in the defined range for the local variable in CodeView. We simply can drop the fragment definition in such a scenario with the variables are "optimized out".
Thanks to @<!-- -->rnk and @<!-- -->hjyamauchi for the discussion around this.
---
Full diff: https://github.com/llvm/llvm-project/pull/75504.diff
2 Files Affected:
- (modified) llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp (+6)
- (added) llvm/test/DebugInfo/codeview-bit-slice-fragments.ll (+67)
``````````diff
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index 3a9d5fa3b936e0..dddc08b3bc0166 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -1397,6 +1397,12 @@ void CodeViewDebug::calculateRanges(
if (Location->Register == 0 || Location->LoadChain.size() > 1)
continue;
+ // Codeview can only express byte-aligned offsets, ensure that we have a
+ // byte-boundaried location.
+ if (Location->FragmentInfo)
+ if (Location->FragmentInfo->OffsetInBits % 8)
+ continue;
+
LocalVarDef DR;
DR.CVRegister = TRI->getCodeViewRegNum(Location->Register);
DR.InMemory = !Location->LoadChain.empty();
diff --git a/llvm/test/DebugInfo/codeview-bit-slice-fragments.ll b/llvm/test/DebugInfo/codeview-bit-slice-fragments.ll
new file mode 100644
index 00000000000000..693ac6e917f480
--- /dev/null
+++ b/llvm/test/DebugInfo/codeview-bit-slice-fragments.ll
@@ -0,0 +1,67 @@
+; RUN: llc -filetype asm -o - %s | FileCheck %s
+
+; Ensure that we do not emit any live ranges for the fragment as it is
+; bit-sliced which cannot be represented in CodeView.
+; CHECK-NOT: .cv_def_range
+
+source_filename = "/tmp/reduced.ll"
+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-unknown-windows-msvc19.37.32825"
+
+define swifttailcc void @"$s12SourceKitLSP0aB6ServerC14workspaceTestsySay08LanguageD8Protocol19WorkspaceSymbolItemOGSgAE0iF7RequestVYaKFTY0_"() !dbg !5 {
+entryresume.0:
+ br label %.from.63
+
+.from.63: ; preds = %.from.63, %entryresume.0
+ %lsr.iv = phi ptr [ %scevgep, %.from.63 ], [ null, %entryresume.0 ]
+ %0 = load i64, ptr %lsr.iv, align 8
+ %1 = load i64, ptr %lsr.iv, align 8
+ call void @llvm.dbg.value(metadata ptr %lsr.iv, metadata !9, metadata !DIExpression(DW_OP_deref, DW_OP_LLVM_fragment, 1, 1)), !dbg !22
+ call void @llvm.dbg.value(metadata ptr %lsr.iv, metadata !9, metadata !DIExpression(DW_OP_deref, DW_OP_LLVM_fragment, 2, 64)), !dbg !22
+ %2 = load volatile ptr, ptr null, align 8, !dbg !30
+ %scevgep = getelementptr i8, ptr %lsr.iv, i64 8
+ br label %.from.63
+}
+
+declare void @llvm.dbg.value(metadata %0, metadata %1, metadata %2) #0
+
+attributes #0 = { nocallback nofree nosync nounwind speculatable willreturn memory(none) }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_Swift, file: !1, producer: "Swift version 5.11-dev (LLVM 572a5a4fbafb69e, Swift ebbb9de104d5682)", isOptimized: true, flags: "-private-discriminator _A0745CB010D215CC0C4A68539F8BE5E9", runtimeVersion: 5, emissionKind: FullDebug, imports: !2, sysroot: "S:/Program Files/Swift/Platforms/Windows.platform/Developer/SDKs/Windows.sdk", sdk: "Windows.sdk")
+!1 = !DIFile(filename: "S:\\SourceCache\\swift-project\\sourcekit-lsp\\Sources\\SourceKitLSP\\TestDiscovery.swift", directory: "S:\\b\14")
+!2 = !{}
+!3 = !{i32 2, !"CodeView", i32 1}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = distinct !DISubprogram(name: "workspaceTests", linkageName: "$s12SourceKitLSP0aB6ServerC14workspaceTestsySay08LanguageD8Protocol19WorkspaceSymbolItemOGSgAE0iF7RequestVYaKFTY0_", scope: !6, file: !1, line: 35, type: !7, scopeLine: 35, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, declaration: !8, retainedNodes: !2, thrownTypes: !2)
+!6 = !DIModule(scope: null, name: "SourceKitLSP", includePath: "S:\\SourceCache\\swift-project\\sourcekit-lsp\\Sources\\SourceKitLSP")
+!7 = !DISubroutineType(types: !2)
+!8 = !DISubprogram(name: "workspaceTests", linkageName: "$s12SourceKitLSP0aB6ServerC14workspaceTestsySay08LanguageD8Protocol19WorkspaceSymbolItemOGSgAE0iF7RequestVYaKFTY0_", scope: !6, file: !1, line: 35, type: !7, scopeLine: 35, spFlags: DISPFlagOptimized, thrownTypes: !2)
+!9 = !DILocalVariable(name: "$0", arg: 1, scope: !10, file: !1, line: 41, type: !18)
+!10 = distinct !DISubprogram(linkageName: "$s12SourceKitLSP0aB6ServerC14workspaceTestsySay08LanguageD8Protocol19WorkspaceSymbolItemOGSgAE0iF7RequestVYaKFSb12IndexStoreDB0J10OccurrenceVXEfU0_", scope: !11, file: !1, line: 41, type: !17, scopeLine: 41, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2, thrownTypes: !13)
+!11 = distinct !DISubprogram(name: "workspaceTests", linkageName: "$s12SourceKitLSP0aB6ServerC14workspaceTestsySay08LanguageD8Protocol19WorkspaceSymbolItemOGSgAE0iF7RequestVYaKF", scope: !6, file: !1, line: 35, type: !7, scopeLine: 35, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, declaration: !12, retainedNodes: !2, thrownTypes: !13)
+!12 = !DISubprogram(name: "workspaceTests", linkageName: "$s12SourceKitLSP0aB6ServerC14workspaceTestsySay08LanguageD8Protocol19WorkspaceSymbolItemOGSgAE0iF7RequestVYaKF", scope: !6, file: !1, line: 35, type: !7, scopeLine: 35, spFlags: DISPFlagOptimized, thrownTypes: !13)
+!13 = !{!14}
+!14 = !DICompositeType(tag: DW_TAG_structure_type, name: "Error", scope: !16, file: !15, size: 64, elements: !2, runtimeLang: DW_LANG_Swift, identifier: "$ss5Error_pD")
+!15 = !DIFile(filename: "S:\\Program Files\\Swift\\Platforms\\Windows.platform\DEveloper\\SDKs\\Windows.sdk\\usr\\lib\\swift\\windows\\Swift.swiftmodule\\x86_64-unknown-windows-msvc.swiftmodule", directory: "S:\\")
+!16 = !DIModule(scope: null, name: "Swift", configMacros: "\22-D_CRT_SECURE_NO_WARNINGS\22 \22-D_MT\22 \22-D_DLL\22", includePath: "S:/Program Files/Swift/Platforms/Windows.platform/Developer/SDKs/Windows.sdk\\usr\\lib\\swift\\windows\\Swift.swiftmodule\\x86_64-unknown-windows-msvc.swiftmodule")
+!17 = distinct !DISubroutineType(types: !2)
+!18 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !19)
+!19 = !DICompositeType(tag: DW_TAG_structure_type, name: "SymbolOccurrence", scope: !21, file: !20, size: 960, elements: !2, runtimeLang: DW_LANG_Swift, identifier: "$s12IndexStoreDB16SymbolOccurrenceVD")
+!20 = !DIFile(filename: "13\\swift\\IndexStoreDB.swiftmodule", directory: "S:\\b")
+!21 = !DIModule(scope: null, name: "IndexStoreDB", configMacros: "\22-D_CRT_SECURE_NO_WARNINGS\22 \22-D_MT\22 \22-D_DLL\22", includePath: "S:\\b\\13\\swift\\IndexStoreDB.swiftmodule")
+!22 = !DILocation(line: 41, scope: !10, inlinedAt: !23)
+!23 = distinct !DILocation(line: 0, scope: !24, inlinedAt: !28)
+!24 = distinct !DISubprogram(name: "filter", linkageName: "$ss14_ArrayProtocolPsE6filterySay7ElementQzGSbAEKXEKFSay12IndexStoreDB16SymbolOccurrenceVG_Tg5", scope: !16, file: !25, type: !26, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, declaration: !27, thrownTypes: !2)
+!25 = !DIFile(filename: "<compiler-generated>", directory: "")
+!26 = distinct !DISubroutineType(types: !2)
+!27 = !DISubprogram(name: "filter", linkageName: "$ss14_ArrayProtocolPsE6filterySay7ElementQzGSbAEKXEKFSay12IndexStoreDB16SymbolOccurrenceVG_Tg5", scope: !16, file: !25, type: !26, spFlags: DISPFlagLocalToUnit | DISPFlagOptimized, thrownTypes: !2)
+!28 = distinct !DILocation(line: 41, scope: !29)
+!29 = distinct !DILexicalBlock(scope: !5, file: !1, line: 36)
+!30 = !DILocation(line: 24, scope: !31, inlinedAt: !34)
+!31 = distinct !DILexicalBlock(scope: !32, file: !1, line: 24)
+!32 = distinct !DISubprogram(name: "canBeTestDefinition.get", linkageName: "$s12IndexStoreDB16SymbolOccurrenceV12SourceKitLSPE19canBeTestDefinition33_A0745CB010D215CC0C4A68539F8BE5E9LLSbvg", scope: !6, file: !1, line: 23, type: !17, scopeLine: 23, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, declaration: !33, retainedNodes: !2)
+!33 = !DISubprogram(name: "canBeTestDefinition.get", linkageName: "$s12IndexStoreDB16SymbolOccurrenceV12SourceKitLSPE19canBeTestDefinition33_A0745CB010D215CC0C4A68539F8BE5E9LLSbvg", scope: !6, file: !1, line: 23, type: !17, scopeLine: 23, spFlags: DISPFlagLocalToUnit | DISPFlagOptimized)
+!34 = distinct !DILocation(line: 41, scope: !10, inlinedAt: !23)
``````````
</details>
https://github.com/llvm/llvm-project/pull/75504
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