[llvm] 21ee38e - [DebugInfo][LSR] Avoid crashes on large integer inputs

[Chris Jackson via llvm-commits]

Author: Chris Jackson
Date: 2021-08-04T15:51:22+01:00
New Revision: 21ee38e24f9801a567306b2a88defacf6e589a8b

URL: https://github.com/llvm/llvm-project/commit/21ee38e24f9801a567306b2a88defacf6e589a8b
DIFF: https://github.com/llvm/llvm-project/commit/21ee38e24f9801a567306b2a88defacf6e589a8b.diff

LOG: [DebugInfo][LSR] Avoid crashes on large integer inputs

SCEV-based salvaging in LSR translates SCEVs to DIExpressions. SCEVs may
contain very large integers but the translation does not support
integers greater than 64 bits. This patch adds checks to ensure
conversions of these large integers is not attempted. A regression test
is added to ensure no such translation is attempted.

Reviewed by: StephenTozer

PR: https://bugs.llvm.org/show_bug.cgi?id=51329

Differential Revision: https://reviews.llvm.org/D107438

Added: 
    llvm/test/Transforms/LoopStrengthReduce/pr51329.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 8bd27481765b7..eea5623b94fc1 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -5914,9 +5914,12 @@ struct SCEVDbgValueBuilder {
     pushValue(V);
   }
 
-  void pushConst(const SCEVConstant *C) {
+  bool pushConst(const SCEVConstant *C) {
+    if (C->getAPInt().getMinSignedBits() > 64)
+      return false;
     Expr.push_back(llvm::dwarf::DW_OP_consts);
     Expr.push_back(C->getAPInt().getSExtValue());
+    return true;
   }
 
   /// Several SCEV types are sequences of the same arithmetic operator applied
@@ -5955,7 +5958,7 @@ struct SCEVDbgValueBuilder {
   bool pushSCEV(const llvm::SCEV *S) {
     bool Success = true;
     if (const SCEVConstant *StartInt = dyn_cast<SCEVConstant>(S)) {
-      pushConst(StartInt);
+      Success &= pushConst(StartInt);
 
     } else if (const SCEVUnknown *U = dyn_cast<SCEVUnknown>(S)) {
       if (!U->getValue())
@@ -6041,6 +6044,8 @@ struct SCEVDbgValueBuilder {
   /// SCEV constant value is an identity function.
   bool isIdentityFunction(uint64_t Op, const SCEV *S) {
     if (const SCEVConstant *C = dyn_cast<SCEVConstant>(S)) {
+      if (C->getAPInt().getMinSignedBits() > 64)
+        return false;
       int64_t I = C->getAPInt().getSExtValue();
       switch (Op) {
       case llvm::dwarf::DW_OP_plus:

diff  --git a/llvm/test/Transforms/LoopStrengthReduce/pr51329.ll b/llvm/test/Transforms/LoopStrengthReduce/pr51329.ll
new file mode 100644
index 0000000000000..f8f1c48eeaa86
--- /dev/null
+++ b/llvm/test/Transforms/LoopStrengthReduce/pr51329.ll
@@ -0,0 +1,50 @@
+; RUN: opt -S -loop-reduce %s | FileCheck %s
+;
+; Test that LSR SCEV-based salvaging does not crash when translating SCEVs
+; that contain integers with binary representations greater than 64-bits. 
+;
+; CHECK: call void @llvm.dbg.value(metadata i64 %var2, metadata !{{[0-9]+}}, metadata !DIExpression(DW_OP_plus_uconst, 228, DW_OP_stack_value))
+
+
+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"
+
+; Function Attrs: nofree nosync nounwind readnone speculatable willreturn
+declare void @llvm.dbg.value(metadata, metadata, metadata)
+
+; Function Attrs: nounwind
+define hidden void @reproducer() local_unnamed_addr !dbg !5 {
+init:
+  %0 = lshr i128 undef, 64
+  %var1 = trunc i128 %0 to i64
+  %1 = add nuw i64 undef, %var1
+  %var2 = lshr i64 %1, 12
+  br label %Label_d0
+
+Label_d0:                                         ; preds = %Label_d0, %init
+  %var3 = phi i64 [ %var2, %init ], [ %var4, %Label_d0 ]
+  call void @llvm.dbg.value(metadata i64 %var2, metadata !11, metadata !DIExpression(DW_OP_plus_uconst, 228, DW_OP_stack_value)), !dbg !12
+  %var4 = add i64 %var3, -1
+  %var5 = icmp eq i64 %var4, 0
+  br i1 %var5, label %Label_1bc, label %Label_d0
+
+Label_1bc:                                        ; preds = %Label_d0
+  ret void
+}
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "frontend", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "source", directory: "")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = !{i32 1, !"wchar_size", i32 4}
+!5 = distinct !DISubprogram(name: "reproducer", scope: !1, file: !1, line: 904320, type: !6, scopeLine: 904320, spFlags: DISPFlagDefinition, unit: !0, retainedNodes: !10)
+!6 = !DISubroutineType(types: !7)
+!7 = !{null, !8, !9, !9, !9, !9, !9, !9}
+!8 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: null, size: 64)
+!9 = !DIBasicType(name: "my_type", size: 64, encoding: DW_ATE_unsigned)
+!10 = !{!11}
+!11 = !DILocalVariable(name: "my_var", arg: 1, scope: !5, file: !1, line: 904320, type: !8)
+!12 = !DILocation(line: 904544, scope: !5)