[clang] [clang][Interp] Implement integral->complex casts (PR #75590)

[Timm Baeder via cfe-commits]

https://github.com/tbaederr updated https://github.com/llvm/llvm-project/pull/75590

>From 09d552b3e700ee8281a55fd63a5c4bc75a94251c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Timm=20B=C3=A4der?= <tbaeder at redhat.com>
Date: Fri, 15 Dec 2023 13:11:16 +0100
Subject: [PATCH] [clang][Interp] Implement integral->complex casts

---
 clang/lib/AST/Interp/ByteCodeExprGen.cpp | 26 ++++++++++++++++++++++++
 clang/test/AST/Interp/complex.cpp        |  9 ++++----
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
index e6b3097a80d8f7..bd9a58042f6cb5 100644
--- a/clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -283,6 +283,28 @@ bool ByteCodeExprGen<Emitter>::VisitCastExpr(const CastExpr *CE) {
   case CK_ToVoid:
     return discard(SubExpr);
 
+  case CK_IntegralRealToComplex:
+  case CK_FloatingRealToComplex: {
+    // We're creating a complex value here, so we need to
+    // allocate storage for it.
+    if (!Initializing) {
+      std::optional<unsigned> LocalIndex =
+          allocateLocal(CE, /*IsExtended=*/true);
+      if (!LocalIndex)
+        return false;
+      if (!this->emitGetPtrLocal(*LocalIndex, CE))
+        return false;
+    }
+
+    if (!this->visitArrayElemInit(0, SubExpr))
+      return false;
+    // Zero-init the second element.
+    PrimType T = classifyPrim(SubExpr->getType());
+    if (!this->visitZeroInitializer(T, SubExpr->getType(), SubExpr))
+      return false;
+    return this->emitInitElem(T, 1, SubExpr);
+  }
+
   default:
     assert(false && "Cast not implemented");
   }
@@ -835,6 +857,10 @@ bool ByteCodeExprGen<Emitter>::VisitInitListExpr(const InitListExpr *E) {
 
   if (T->isAnyComplexType()) {
     unsigned NumInits = E->getNumInits();
+
+    if (NumInits == 1)
+      return this->delegate(E->inits()[0]);
+
     QualType ElemQT = E->getType()->getAs<ComplexType>()->getElementType();
     PrimType ElemT = classifyPrim(ElemQT);
     if (NumInits == 0) {
diff --git a/clang/test/AST/Interp/complex.cpp b/clang/test/AST/Interp/complex.cpp
index 66490e973988bb..bf340d6e3ff68a 100644
--- a/clang/test/AST/Interp/complex.cpp
+++ b/clang/test/AST/Interp/complex.cpp
@@ -37,21 +37,20 @@ constexpr _Complex int I2 = {};
 static_assert(__real(I2) == 0, "");
 static_assert(__imag(I2) == 0, "");
 
+static_assert(__real((_Complex unsigned)5) == 5);
+static_assert(__imag((_Complex unsigned)5) == 0);
 
 /// Standalone complex expressions.
 static_assert(__real((_Complex float){1.0, 3.0}) == 1.0, "");
 
 
-#if 0
-/// FIXME: This should work in the new interpreter.
 constexpr _Complex double D2 = {12};
 static_assert(__real(D2) == 12, "");
-static_assert(__imag(D2) == 12, "");
+static_assert(__imag(D2) == 0, "");
 
 constexpr _Complex int I3 = {15};
 static_assert(__real(I3) == 15, "");
-static_assert(__imag(I3) == 15, "");
-#endif
+static_assert(__imag(I3) == 0, "");
 
 /// FIXME: This should work in the new interpreter as well.
 // constexpr _Complex _BitInt(8) A = 0;// = {4};