[llvm] 914066f - [DebugInfo] Avoid LSR crash on large integer inputs
Jeremy Morse via llvm-commits
llvm-commits at lists.llvm.org
Tue Jan 5 02:27:06 PST 2021
Author: Jeremy Morse
Date: 2021-01-05T10:25:37Z
New Revision: 914066fe38a93c004b742a696ec337701eb738ec
URL: https://github.com/llvm/llvm-project/commit/914066fe38a93c004b742a696ec337701eb738ec
DIFF: https://github.com/llvm/llvm-project/commit/914066fe38a93c004b742a696ec337701eb738ec.diff
LOG: [DebugInfo] Avoid LSR crash on large integer inputs
Loop strength reduction tries to recover debug variable values by looking
for simple offsets from PHI values. In really extreme conditions there may
be an offset used that won't fit in an int64_t, hitting an APInt assertion.
This patch adds a regression test and adjusts the equivalent value
collecting code to filter out any values where the offset can't be
represented by an int64_t. This means that for very large integers with
very large offsets, the variable location will become undef, which is the
same behaviour as before 2a6782bb9f1 / D87494.
Differential Revision: https://reviews.llvm.org/D94016
Added:
llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll
Modified:
llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index 7742ebafcac4..6e64a1ddf787 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -5796,8 +5796,9 @@ static void DbgGatherEqualValues(Loop *L, ScalarEvolution &SE,
if (!SE.isSCEVable(Phi.getType()))
continue;
auto PhiSCEV = SE.getSCEV(&Phi);
- if (Optional<APInt> Offset =
- SE.computeConstantDifference(DbgValueSCEV, PhiSCEV))
+ Optional<APInt> Offset =
+ SE.computeConstantDifference(DbgValueSCEV, PhiSCEV);
+ if (Offset && Offset->getMinSignedBits() <= 64)
EqSet.emplace_back(std::make_tuple(
&Phi, Offset.getValue().getSExtValue(), DVI->getExpression()));
}
diff --git a/llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll b/llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll
new file mode 100644
index 000000000000..d651ff239a46
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/dbg-preserve-1.ll
@@ -0,0 +1,73 @@
+; RUN: opt < %s -loop-reduce -S | FileCheck %s
+;
+; Test that LSR avoids crashing on very large integer inputs. It should
+; discard the variable location by creating an undef dbg.value.
+;
+; CHECK: call void @llvm.dbg.value(metadata i128 undef,
+
+source_filename = "<stdin>"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define dso_local void @qux() local_unnamed_addr !dbg !10 {
+entry:
+ br label %for.body, !dbg !17
+
+for.body: ; preds = %for.body.for.body_crit_edge, %entry
+ %0 = phi i128 [ 0, %entry ], [ %.pre8, %for.body.for.body_crit_edge ], !dbg !19
+ %add6.i.i = add i128 %0, 18446744073709551615, !dbg !35
+ call void @llvm.dbg.value(metadata i128 %add6.i.i, metadata !25, metadata !DIExpression(DW_OP_LLVM_fragment, 0, 128)), !dbg !36
+ br label %for.body.for.body_crit_edge
+
+for.body.for.body_crit_edge: ; preds = %for.body
+ %.pre8 = load i128, i128* undef, align 16, !dbg !19, !tbaa !37
+ br label %for.body, !dbg !17
+}
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!7, !8, !9}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2, retainedTypes: !3, globals: !2, splitDebugInlining: false, nameTableKind: None)
+!1 = !DIFile(filename: "/tmp/beans.c", directory: "/tmp")
+!2 = !{}
+!3 = !{!4}
+!4 = !DIDerivedType(tag: DW_TAG_typedef, name: "uint64_t", file: !5, line: 1, baseType: !6)
+!5 = !DIFile(filename: "/tmp/beans.c", directory: "")
+!6 = !DIBasicType(name: "long unsigned int", size: 64, encoding: DW_ATE_unsigned)
+!7 = !{i32 7, !"Dwarf Version", i32 4}
+!8 = !{i32 2, !"Debug Info Version", i32 3}
+!9 = !{i32 1, !"wchar_size", i32 4}
+!10 = distinct !DISubprogram(name: "qux", scope: !5, file: !5, line: 27, type: !11, scopeLine: 27, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!11 = !DISubroutineType(types: !12)
+!12 = !{null, !13, !13}
+!13 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !14, size: 64)
+!14 = !DIDerivedType(tag: DW_TAG_typedef, name: "croix", file: !5, line: 2, baseType: !15)
+!15 = !DIDerivedType(tag: DW_TAG_typedef, name: "__uint128_t", file: !1, baseType: !16)
+!16 = !DIBasicType(name: "unsigned __int128", size: 128, encoding: DW_ATE_unsigned)
+!17 = !DILocation(line: 30, column: 3, scope: !18)
+!18 = distinct !DILexicalBlock(scope: !10, file: !5, line: 30, column: 3)
+!19 = !DILocation(line: 12, column: 25, scope: !20, inlinedAt: !30)
+!20 = distinct !DISubprogram(name: "bar", scope: !5, file: !5, line: 8, type: !21, scopeLine: 8, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagLocalToUnit | DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !24)
+!21 = !DISubroutineType(types: !22)
+!22 = !{null, !23, !13}
+!23 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !4, size: 64)
+!24 = !{!25}
+!25 = !DILocalVariable(name: "tmp", scope: !20, file: !5, line: 9, type: !26)
+!26 = !DIDerivedType(tag: DW_TAG_typedef, name: "xyzzy", file: !5, line: 3, baseType: !27)
+!27 = !DICompositeType(tag: DW_TAG_array_type, baseType: !14, size: 512, elements: !28)
+!28 = !{!29}
+!29 = !DISubrange(count: 4)
+!30 = distinct !DILocation(line: 23, column: 3, scope: !31, inlinedAt: !32)
+!31 = distinct !DISubprogram(name: "baz", scope: !5, file: !5, line: 21, type: !11, scopeLine: 21, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !2)
+!32 = distinct !DILocation(line: 31, column: 5, scope: !33)
+!33 = distinct !DILexicalBlock(scope: !34, file: !5, line: 30, column: 31)
+!34 = distinct !DILexicalBlock(scope: !18, file: !5, line: 30, column: 3)
+!35 = !DILocation(line: 12, column: 23, scope: !20, inlinedAt: !30)
+!36 = !DILocation(line: 0, scope: !20, inlinedAt: !30)
+!37 = !{!38, !38, i64 0}
+!38 = !{!"__int128", !39, i64 0}
+!39 = !{!"omnipotent char", !40, i64 0}
+!40 = !{!"Simple C/C++ TBAA"}
More information about the llvm-commits
mailing list