[llvm] 0f11a5f - Revert "[DebugInfo] Fix detection of hash collision in Apple Accel tables"

[Felipe de Azevedo Piovezan via llvm-commits]

Author: Felipe de Azevedo Piovezan
Date: 2023-06-15T12:36:58-04:00
New Revision: 0f11a5f172482626f1900b692082d46030561953

URL: https://github.com/llvm/llvm-project/commit/0f11a5f172482626f1900b692082d46030561953
DIFF: https://github.com/llvm/llvm-project/commit/0f11a5f172482626f1900b692082d46030561953.diff

LOG: Revert "[DebugInfo] Fix detection of hash collision in Apple Accel tables"

Committed a slightly older patch without the proper link to the review.

This reverts commit 42874f66475548541cd871d5790116b2bc68b89a.

Added: 
    

Modified: 
    llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp

Removed: 
    llvm/test/DebugInfo/Generic/apple-names-hash-collisions.ll


################################################################################
diff  --git a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
index 03bc8a835b4b8..cda822d92aead 100644
--- a/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFAcceleratorTable.cpp
@@ -333,19 +333,22 @@ AppleAcceleratorTable::equal_range(StringRef Key) const {
     return EmptyRange;
 
   std::optional<uint32_t> StrOffset = readStringOffsetAt(DataOffset);
-  // Valid input and still have strings in this hash.
-  while (StrOffset && *StrOffset) {
-    std::optional<StringRef> MaybeStr = readStringFromStrSection(*StrOffset);
-    std::optional<uint32_t> NumEntries = this->readU32FromAccel(DataOffset);
-    if (!MaybeStr || !NumEntries)
-      return EmptyRange;
+
+  // Invalid input or no more strings in this hash.
+  if (!StrOffset || *StrOffset == 0)
+    return EmptyRange;
+
+  std::optional<StringRef> MaybeStr = readStringFromStrSection(*StrOffset);
+  std::optional<uint32_t> NumEntries = this->readU32FromAccel(DataOffset);
+  if (!MaybeStr || !NumEntries)
+    return EmptyRange;
+  if (Key == *MaybeStr) {
     uint64_t EndOffset = DataOffset + *NumEntries * getHashDataEntryLength();
-    if (Key == *MaybeStr)
-      return make_range({*this, DataOffset}, ValueIterator{*this, EndOffset});
-    DataOffset = EndOffset;
-    StrOffset = readStringOffsetAt(DataOffset);
+    return make_range({*this, DataOffset}, ValueIterator{*this, EndOffset});
   }
 
+  // FIXME: this shouldn't return, we haven't checked all the colliding strings
+  // in the bucket!
   return EmptyRange;
 }
 

diff  --git a/llvm/test/DebugInfo/Generic/apple-names-hash-collisions.ll b/llvm/test/DebugInfo/Generic/apple-names-hash-collisions.ll
deleted file mode 100644
index 5e20127a2e2ca..0000000000000
--- a/llvm/test/DebugInfo/Generic/apple-names-hash-collisions.ll
+++ /dev/null
@@ -1,36 +0,0 @@
-; RUN: %llc_dwarf -accel-tables=Apple -filetype=obj -o %t < %s
-; RUN: llvm-dwarfdump -apple-names %t | FileCheck %s --check-prefix=NUM_HASHES
-; RUN: llvm-dwarfdump  --find=bb --find=cA %t | FileCheck %s --check-prefix=FOUND_VARS
-
-
-; The strings 'bb' and 'cA' hash to the same value under the Apple accelerator
-; table hashing algorithm.
-; We first test that there is exactly one bucket and one hash.
-; Then we check that both values are found.
-
-; NUM_HASHES:      Bucket count: 1
-; NUM_HASHES-NEXT: Hashes count: 1
-; FOUND_VARS: DW_AT_name        ("bb")
-; FOUND_VARS: DW_AT_name        ("cA")
-
- at bb = global i32 200, align 4, !dbg !0
- at cA = global i32 10, align 4, !dbg !5
-
-!llvm.module.flags = !{!9, !10, !11, !12, !13}
-!llvm.dbg.cu = !{!2}
-!llvm.ident = !{!15}
-
-!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
-!1 = distinct !DIGlobalVariable(name: "bb", scope: !2, file: !3, line: 1, type: !7, isDefinition: true)
-!2 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus_14, file: !3, producer: "", emissionKind: FullDebug, globals: !4)
-!3 = !DIFile(filename: "test.cpp", directory: "blah")
-!4 = !{!0, !5}
-!5 = !DIGlobalVariableExpression(var: !6, expr: !DIExpression())
-!6 = distinct !DIGlobalVariable(name: "cA", scope: !2, file: !3, line: 2, type: !7, isLocal: false, isDefinition: true)
-!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!9 = !{i32 7, !"Dwarf Version", i32 4}
-!10 = !{i32 2, !"Debug Info Version", i32 3}
-!11 = !{i32 1, !"wchar_size", i32 4}
-!12 = !{i32 8, !"PIC Level", i32 2}
-!13 = !{i32 7, !"uwtable", i32 1}
-!15 = !{!"blah"}