Index: llvm/lib/IR/DebugInfo.cpp =================================================================== --- llvm/lib/IR/DebugInfo.cpp +++ llvm/lib/IR/DebugInfo.cpp @@ -1915,7 +1915,8 @@ } /// Collect constant properies (base, size, offset) of \p StoreDest. -/// Return std::nullopt if any properties are not constants. +/// Return std::nullopt if any properties are not constants or the +/// offset from the base pointer is negative. static std::optional getAssignmentInfoImpl(const DataLayout &DL, const Value *StoreDest, TypeSize SizeInBits) { @@ -1924,6 +1925,10 @@ APInt GEPOffset(DL.getIndexTypeSizeInBits(StoreDest->getType()), 0); const Value *Base = StoreDest->stripAndAccumulateConstantOffsets( DL, GEPOffset, /*AllowNonInbounds*/ true); + + if (GEPOffset.isNegative()) + return std::nullopt; + uint64_t OffsetInBytes = GEPOffset.getLimitedValue(); // Check for overflow. if (OffsetInBytes == UINT64_MAX) Index: llvm/test/DebugInfo/assignment-tracking/X86/negative-offset.ll =================================================================== --- /dev/null +++ llvm/test/DebugInfo/assignment-tracking/X86/negative-offset.ll @@ -0,0 +1,91 @@ +; RUN: llc %s -stop-after=finalize-isel -o - | FileCheck %s --implicit-check-not=DBG_VALUE + +;; Check stores to an address computed as a negative offset from a alloca are +;; ignored by the assignment tracking analysis. In this case the result is +;; there should be no DBG_VALUE in the while.body.lr.ph branch. +;; +;; See llvm.org/PR62838 for more info. +;; +;; $ clang test.c -O1 -g +;; $ cat tes.c +;; void a(int *p); +;; __attribute__((nodebug)) int b; +;; +;; int main() { +;; int c[1]; +;; __attribute__((nodebug)) int d = -1; +;; +;; while (b) { +;; c[0] = 0; +;; c[d] = 0; +;; } +;; a(c); +;; return 0; +;; } + +; CHECK: bb.0.entry: +; CHECK-NEXT: successors +; CHECK-NEXT: {{^ *$}} +; CHECK-NEXT: DBG_VALUE %stack.0.c, $noreg, ![[#]], !DIExpression(DW_OP_deref) + +; CHECK: bb.2.while.body: +; CHECK-NEXT: successors +; CHECK-NEXT: {{^ *$}} +; CHECK-NEXT: DBG_VALUE 0, $noreg, ![[#]], !DIExpression() + +target triple = "x86_64-unknown-linux-gnu" + +@b = dso_local local_unnamed_addr global i32 0, align 4 + +define dso_local i32 @main() local_unnamed_addr #0 !dbg !10 { +entry: + %c = alloca [1 x i32], align 4, !DIAssignID !19 + call void @llvm.dbg.assign(metadata i1 undef, metadata !15, metadata !DIExpression(), metadata !19, metadata ptr %c, metadata !DIExpression()), !dbg !20 + %0 = load i32, ptr @b, align 4 + %tobool.not = icmp eq i32 %0, 0 + br i1 %tobool.not, label %while.end, label %while.body.lr.ph + +while.body.lr.ph: ; preds = %entry + %arrayidx1 = getelementptr inbounds [1 x i32], ptr %c, i64 0, i64 -1 + store i32 0, ptr %arrayidx1, align 4 + br label %while.body + +while.body: ; preds = %while.body, %while.body.lr.ph + call void @llvm.dbg.assign(metadata i32 0, metadata !15, metadata !DIExpression(), metadata !28, metadata ptr %c, metadata !DIExpression()), !dbg !20 + br label %while.body + +while.end: ; preds = %entry + call void @a(ptr noundef nonnull %c) + ret i32 0 +} + +declare !dbg !31 void @a(ptr noundef) local_unnamed_addr #2 +declare void @llvm.dbg.assign(metadata, metadata, metadata, metadata, metadata, metadata) #3 + +!llvm.dbg.cu = !{!0} +!llvm.module.flags = !{!2, !3, !8} +!llvm.ident = !{!9} + +!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang version 17.0.0)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None) +!1 = !DIFile(filename: "test.c", directory: "/") +!2 = !{i32 7, !"Dwarf Version", i32 5} +!3 = !{i32 2, !"Debug Info Version", i32 3} +!8 = !{i32 7, !"debug-info-assignment-tracking", i1 true} +!9 = !{!"clang version 17.0.0"} +!10 = distinct !DISubprogram(name: "main", scope: !1, file: !1, line: 4, type: !11, scopeLine: 4, flags: DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !14) +!11 = !DISubroutineType(types: !12) +!12 = !{!13} +!13 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed) +!14 = !{!15} +!15 = !DILocalVariable(name: "c", scope: !10, file: !1, line: 5, type: !16) +!16 = !DICompositeType(tag: DW_TAG_array_type, baseType: !13, size: 32, elements: !17) +!17 = !{!18} +!18 = !DISubrange(count: 1) +!19 = distinct !DIAssignID() +!20 = !DILocation(line: 0, scope: !10) +!28 = distinct !DIAssignID() +!31 = !DISubprogram(name: "a", scope: !1, file: !1, line: 1, type: !32, flags: DIFlagPrototyped, spFlags: DISPFlagOptimized, retainedNodes: !35) +!32 = !DISubroutineType(types: !33) +!33 = !{null, !34} +!34 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !13, size: 64) +!35 = !{}