[clang] [clang][bytecode] Handle vector assignments (PR #155573)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr updated 
https://github.com/llvm/llvm-project/pull/155573

>From d39fd952f001650ae503b122ca3e7d2adf8c0601 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbae...@redhat.com>
Date: Wed, 27 Aug 2025 10:29:40 +0200
Subject: [PATCH] [clang][bytecode] Handle vector assignments

---
 clang/lib/AST/ByteCode/Compiler.cpp | 17 ++++++++++++++++-
 clang/test/AST/ByteCode/vectors.cpp | 25 +++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/clang/lib/AST/ByteCode/Compiler.cpp 
b/clang/lib/AST/ByteCode/Compiler.cpp
index 0079d937e885b..c909858f6df5a 100644
--- a/clang/lib/AST/ByteCode/Compiler.cpp
+++ b/clang/lib/AST/ByteCode/Compiler.cpp
@@ -1383,7 +1383,7 @@ bool Compiler<Emitter>::VisitVectorBinOp(const 
BinaryOperator *E) {
   assert(E->getRHS()->getType()->isVectorType());
 
   // Prepare storage for result.
-  if (!Initializing && !E->isCompoundAssignmentOp()) {
+  if (!Initializing && !E->isCompoundAssignmentOp() && !E->isAssignmentOp()) {
     UnsignedOrNone LocalIndex = allocateTemporary(E);
     if (!LocalIndex)
       return false;
@@ -1402,6 +1402,21 @@ bool Compiler<Emitter>::VisitVectorBinOp(const 
BinaryOperator *E) {
   PrimType RHSElemT = this->classifyVectorElementType(RHS->getType());
   PrimType ResultElemT = this->classifyVectorElementType(E->getType());
 
+  if (E->getOpcode() == BO_Assign) {
+    assert(Ctx.getASTContext().hasSameUnqualifiedType(
+        LHS->getType()->castAs<VectorType>()->getElementType(),
+        RHS->getType()->castAs<VectorType>()->getElementType()));
+    if (!this->visit(LHS))
+      return false;
+    if (!this->visit(RHS))
+      return false;
+    if (!this->emitCopyArray(ElemT, 0, 0, VecTy->getNumElements(), E))
+      return false;
+    if (DiscardResult)
+      return this->emitPopPtr(E);
+    return true;
+  }
+
   // Evaluate LHS and save value to LHSOffset.
   unsigned LHSOffset =
       this->allocateLocalPrimitive(LHS, PT_Ptr, /*IsConst=*/true);
diff --git a/clang/test/AST/ByteCode/vectors.cpp 
b/clang/test/AST/ByteCode/vectors.cpp
index 091caf8c9a275..6b41c8d79d5b4 100644
--- a/clang/test/AST/ByteCode/vectors.cpp
+++ b/clang/test/AST/ByteCode/vectors.cpp
@@ -143,3 +143,28 @@ namespace {
   constexpr __m128d v_mm_cvtps_pd = _mm_cvtps_pd(kf1);
   static_assert(v_mm_cvtps_pd[0] == -1.0 && v_mm_cvtps_pd[1] == +2.0);
 }
+
+namespace Assign {
+  constexpr int a2() {
+      VI a = {0, 0, 0, 0};
+      VI b; // both-warning {{C++20 extension}}
+
+      b = {1,1,1,1};
+      return b[0] + b[1] + b[2] + b[3];
+  }
+
+  static_assert(a2() == 4);
+
+  typedef short          v2int16_t __attribute__((ext_vector_type(2)));
+  typedef unsigned short v2int_t __attribute__((ext_vector_type(2)));
+
+
+  constexpr bool invalid() {
+    v2int16_t a = {0, 0};
+    v2int_t b; // both-warning {{C++20 extension}}
+    b = a; // both-error {{incompatible type}}
+
+    return true;
+  }
+  static_assert(invalid()); // both-error {{not an integral constant 
expression}}
+}

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