Final fix for issue ldc-developers#424

Author: redstar

dmd2/expression.h

@@ -1351,6 +1351,9 @@ class VectorExp : public UnaExp
     Expression *semantic(Scope *sc);
     void toCBuffer(OutBuffer *buf, HdrGenState *hgs);
     elem *toElem(IRState *irs);
+#if IN_LLVM
+    llvm::Constant *toConstElem(IRState *irs);
+#endif
 #if IN_DMD
     dt_t **toDt(dt_t **pdt);
 #endif

dmd2/init.c

@@ -887,10 +887,6 @@ Initializer *ExpInitializer::semantic(Scope *sc, Type *t, NeedInterpret needInte
 
     // Look for the case of statically initializing an array
     // with a single member.
-#if IN_LLVM
-    // Fix for part 1 of issue 424.
-    if (tb->ty == Tvector) tb = static_cast<TypeVector *>(tb)->basetype;
-#endif
     if (tb->ty == Tsarray &&
         !tb->nextOf()->equals(ti->toBasetype()->nextOf()) &&
         exp->implicitConvTo(tb->nextOf())

gen/toir.cpp

@@ -3551,6 +3551,32 @@ DValue* VectorExp::toElem(IRState* p)
 
 //////////////////////////////////////////////////////////////////////////////////////////
 
+llvm::Constant* VectorExp::toConstElem(IRState* p)
+{
+    Logger::print("VectorExp::toConstElem: %s @ %s\n", toChars(), type->toChars());
+    LOG_SCOPE;
+
+    TypeVector *tv = static_cast<TypeVector*>(to->toBasetype());
+    assert(tv->ty == Tvector);
+
+    // The AST for
+    //   static immutable ubyte16 vec1 = 123;
+    // differs from
+    //    static immutable ubyte[16] vec1 = 123;
+    // In the vector case the AST contains an IntegerExp (of type int) and a
+    // CastExp to type ubyte. In the static array case the AST only contains an
+    // IntegerExp of type ubyte. Simply call optimize to get  rid of the cast.
+    // FIXME: Check DMD source to understand why two different ASTs are
+    //        constructed.
+    llvm::Constant *val = e1->optimize(WANTvalue)->toConstElem(p);
+
+    dinteger_t elemCount =
+        static_cast<TypeSArray *>(tv->basetype)->dim->toInteger();
+    return llvm::ConstantVector::getSplat(elemCount, val);
+}
+
+//////////////////////////////////////////////////////////////////////////////////////////
+
 #define STUB(x) DValue *x::toElem(IRState * p) {error("Exp type "#x" not implemented: %s", toChars()); fatal(); return 0; }
 STUB(Expression)
 STUB(ScopeExp)