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author
Eli Friedman
committedAug 24, 2018
[SafeStack] Set debug location for calls to __safestack_pointer_address.
Otherwise, the debug info is incorrect. On its own, this is mostly harmless, but the safe-stack also later inlines the call to __safestack_pointer_address, which leads to debug info with the wrong scope, which eventually causes an assertion failure (and incorrect debug info in release mode). Differential Revision: https://reviews.llvm.org/D51075 llvm-svn: 340651
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llvmorg-21-initllvmorg-8.0.0-rc1
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‎llvm/lib/CodeGen/SafeStack.cpp

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@@ -775,6 +775,10 @@ bool SafeStack::run() {
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++NumUnsafeStackRestorePointsFunctions;
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IRBuilder<> IRB(&F.front(), F.begin()->getFirstInsertionPt());
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// Calls must always have a debug location, or else inlining breaks. So
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// we explicitly set a artificial debug location here.
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if (DISubprogram *SP = F.getSubprogram())
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IRB.SetCurrentDebugLocation(DebugLoc::get(SP->getScopeLine(), 0, SP));
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if (SafeStackUsePointerAddress) {
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Value *Fn = F.getParent()->getOrInsertFunction(
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"__safestack_pointer_address", StackPtrTy->getPointerTo(0));

‎llvm/test/Transforms/SafeStack/ARM/debug.ll

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; RUN: opt -safe-stack -safestack-use-pointer-address < %s -S | FileCheck %s
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target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
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target triple = "armv7-pc-linux-android"
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; Original C used to generate debug info:
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; char*** addr;
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; char** __safestack_pointer_address() {
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; return *addr;
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; }
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; void Capture(char*x);
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; void f() { char c[16]; Capture(c); }
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; CHECK: !35 = !DILocation(line: 3, column: 11, scope: !17, inlinedAt: !36)
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; CHECK: !36 = distinct !DILocation(line: 6, scope: !27)
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@addr = common local_unnamed_addr global i8*** null, align 4, !dbg !0
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; Function Attrs: norecurse nounwind readonly safestack
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define i8** @__safestack_pointer_address() local_unnamed_addr #0 !dbg !17 {
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entry:
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%0 = load i8***, i8**** @addr, align 4, !dbg !20, !tbaa !21
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%1 = load i8**, i8*** %0, align 4, !dbg !25, !tbaa !21
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ret i8** %1, !dbg !26
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}
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; Function Attrs: nounwind safestack
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define void @f() local_unnamed_addr #1 !dbg !27 {
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entry:
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%c = alloca [16 x i8], align 1
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%0 = getelementptr inbounds [16 x i8], [16 x i8]* %c, i32 0, i32 0, !dbg !35
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call void @llvm.lifetime.start.p0i8(i64 16, i8* nonnull %0) #5, !dbg !35
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call void @llvm.dbg.declare(metadata [16 x i8]* %c, metadata !31, metadata !DIExpression()), !dbg !36
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call void @Capture(i8* nonnull %0) #5, !dbg !37
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call void @llvm.lifetime.end.p0i8(i64 16, i8* nonnull %0) #5, !dbg !38
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ret void, !dbg !38
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}
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; Function Attrs: argmemonly nounwind
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declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture) #2
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; Function Attrs: nounwind readnone speculatable
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declare void @llvm.dbg.declare(metadata, metadata, metadata) #3
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declare void @Capture(i8*) local_unnamed_addr #4
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; Function Attrs: argmemonly nounwind
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declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture) #2
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attributes #0 = { norecurse nounwind readonly safestack "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+armv7-a,+dsp,+neon,+vfp3,-thumb-mode" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #1 = { nounwind safestack "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-jump-tables"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+armv7-a,+dsp,+neon,+vfp3,-thumb-mode" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #2 = { argmemonly nounwind }
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attributes #3 = { nounwind readnone speculatable }
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attributes #4 = { "correctly-rounded-divide-sqrt-fp-math"="false" "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "no-signed-zeros-fp-math"="false" "no-trapping-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="generic" "target-features"="+armv7-a,+dsp,+neon,+vfp3,-thumb-mode" "unsafe-fp-math"="false" "use-soft-float"="false" }
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attributes #5 = { nounwind }
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!llvm.dbg.cu = !{!2}
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!llvm.module.flags = !{!11, !12, !13, !14, !15}
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!llvm.ident = !{!16}
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!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
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!1 = distinct !DIGlobalVariable(name: "addr", scope: !2, file: !6, line: 1, type: !7, isLocal: false, isDefinition: true)
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!2 = distinct !DICompileUnit(language: DW_LANG_C99, file: !3, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !4, globals: !5)
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!3 = !DIFile(filename: "-", directory: "/")
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!4 = !{}
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!5 = !{!0}
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!6 = !DIFile(filename: "<stdin>", directory: "/")
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!7 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !8, size: 32)
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!8 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !9, size: 32)
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!9 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !10, size: 32)
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!10 = !DIBasicType(name: "char", size: 8, encoding: DW_ATE_unsigned_char)
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!11 = !{i32 2, !"Dwarf Version", i32 4}
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!12 = !{i32 2, !"Debug Info Version", i32 3}
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!13 = !{i32 1, !"wchar_size", i32 4}
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!14 = !{i32 1, !"min_enum_size", i32 4}
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!15 = !{i32 7, !"PIC Level", i32 1}
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!16 = !{!"clang"}
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!17 = distinct !DISubprogram(name: "__safestack_pointer_address", scope: !6, file: !6, line: 2, type: !18, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: true, unit: !2, retainedNodes: !4)
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!18 = !DISubroutineType(types: !19)
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!19 = !{!8}
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!20 = !DILocation(line: 3, column: 11, scope: !17)
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!21 = !{!22, !22, i64 0}
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!22 = !{!"any pointer", !23, i64 0}
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!23 = !{!"omnipotent char", !24, i64 0}
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!24 = !{!"Simple C/C++ TBAA"}
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!25 = !DILocation(line: 3, column: 10, scope: !17)
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!26 = !DILocation(line: 3, column: 3, scope: !17)
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!27 = distinct !DISubprogram(name: "f", scope: !6, file: !6, line: 6, type: !28, isLocal: false, isDefinition: true, scopeLine: 6, isOptimized: true, unit: !2, retainedNodes: !30)
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!28 = !DISubroutineType(types: !29)
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!29 = !{null}
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!30 = !{!31}
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!31 = !DILocalVariable(name: "c", scope: !27, file: !6, line: 6, type: !32)
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!32 = !DICompositeType(tag: DW_TAG_array_type, baseType: !10, size: 128, elements: !33)
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!33 = !{!34}
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!34 = !DISubrange(count: 16)
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!35 = !DILocation(line: 6, column: 12, scope: !27)
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!36 = !DILocation(line: 6, column: 17, scope: !27)
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!37 = !DILocation(line: 6, column: 24, scope: !27)
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!38 = !DILocation(line: 6, column: 36, scope: !27)

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