[clang] d5c8af4 - [clang][bytecode] Consider start index when copying composite array (#121461)

[via cfe-commits]

Author: Timm Baeder
Date: 2025-01-02T10:31:49+01:00
New Revision: d5c8af492f2d8620b04330024d46a5f48db546fe

URL: https://github.com/llvm/llvm-project/commit/d5c8af492f2d8620b04330024d46a5f48db546fe
DIFF: https://github.com/llvm/llvm-project/commit/d5c8af492f2d8620b04330024d46a5f48db546fe.diff

LOG: [clang][bytecode] Consider start index when copying composite array (#121461)

... elements.

Added: 
    

Modified: 
    clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp
    clang/test/AST/ByteCode/builtin-functions.cpp

Removed: 
    


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diff  --git a/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp b/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp
index 0fc94e1694822a..57c1fab5d6ab43 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltinBitCast.cpp
@@ -110,7 +110,7 @@ static bool enumerateData(const Pointer &P, const Context &Ctx, Bits Offset,
   if (FieldDesc->isCompositeArray()) {
     QualType ElemType = FieldDesc->getElemQualType();
     Bits ElemSize = Bits(Ctx.getASTContext().getTypeSize(ElemType));
-    for (unsigned I = 0; I != FieldDesc->getNumElems(); ++I) {
+    for (unsigned I = P.getIndex(); I != FieldDesc->getNumElems(); ++I) {
       enumerateData(P.atIndex(I).narrow(), Ctx, Offset, BitsToRead, F);
       Offset += ElemSize;
       if (Offset >= BitsToRead)

diff  --git a/clang/test/AST/ByteCode/builtin-functions.cpp b/clang/test/AST/ByteCode/builtin-functions.cpp
index b0f8ea2e55ee0b..0188e8297db528 100644
--- a/clang/test/AST/ByteCode/builtin-functions.cpp
+++ b/clang/test/AST/ByteCode/builtin-functions.cpp
@@ -1253,6 +1253,16 @@ namespace BuiltinMemcpy {
   static_assert(test_memmove(2, 0, 12) == 4234); // both-error {{constant}} \
                                                  // both-note {{in call}}
 #endif
+
+  struct Trivial { char k; short s; constexpr bool ok() { return k == 3 && s == 4; } };
+  constexpr bool test_trivial() {
+    Trivial arr[3] = {{1, 2}, {3, 4}, {5, 6}};
+    __builtin_memcpy(arr, arr+1, sizeof(Trivial));
+    __builtin_memmove(arr+1, arr, 2 * sizeof(Trivial));
+
+    return arr[0].ok() && arr[1].ok() && arr[2].ok();
+  }
+  static_assert(test_trivial());
 }
 
 namespace Memcmp {