Added pragma extractelement

dmd2/idgen.c

@@ -274,6 +274,7 @@ Msgtable msgtable[] =
     { "no_moduleinfo" },
     { "Alloca", "alloca" },
     { "Shufflevector", "shufflevector" },
+    { "Extractelement", "extractelement" },
     { "vastart", "va_start" },
     { "vacopy", "va_copy" },
     { "vaend", "va_end" },

gen/pragma.cpp

@@ -116,6 +116,17 @@ Pragma DtoGetPragma(Scope *sc, PragmaDeclaration *decl, std::string &arg1str)
         return LLVMshufflevector;
     }
 
+    // pragma(extractelement) { funcdecl(s) }
+    else if (ident == Id::Extractelement)
+    {
+        if (args && args->dim > 0)
+        {
+             error("takes no parameters");
+             fatal();
+        }
+        return LLVMextractelement;
+    }
+
     // pragma(va_start) { templdecl(s) }
     else if (ident == Id::vastart)
     {
@@ -375,6 +386,18 @@ void DtoCheckPragma(PragmaDeclaration *decl, Dsymbol *s,
         }
         break;
 
+    case LLVMextractelement:
+        if (FuncDeclaration* fd = s->isFuncDeclaration())
+        {
+            fd->llvmInternal = llvm_internal;
+        }
+        else
+        {
+            error("the '%s' pragma must only be used on function declarations.", ident->toChars());
+            fatal();
+        }
+        break;
+
     case LLVMinline_asm:
         if (TemplateDeclaration* td = s->isTemplateDeclaration())
         {

gen/pragma.h

@@ -15,6 +15,7 @@ enum Pragma
     LLVMno_moduleinfo,
     LLVMalloca,
     LLVMshufflevector,
+    LLVMextractelement,
     LLVMva_start,
     LLVMva_copy,
     LLVMva_end,

gen/toir.cpp

@@ -1007,7 +1007,19 @@ DValue* CallExp::toElem(IRState* p)
             LLValue* v1 = exp1->toElem(p)->getRVal();
             LLValue* v2 = exp2->toElem(p)->getRVal();
             return new DImValue(type, p->ir->CreateShuffleVector(v1, v2, maskVal));
-        } 
+        }
+        // extractelement
+        else if(fndecl->llvmInternal == LLVMextractelement) {
+            Expression* exp2 = static_cast<Expression*>(arguments->data[1]);
+            if(exp2->op != TOKint64){
+                error("Function %s was declared with pragma extractelement. Because of that its second argument must be an integer literal.", fndecl->toChars());
+                fatal();
+            }
+            LLConstant* idx = static_cast<IntegerExp*>(arguments->data[1])->toConstElem(p);
+            Expression* exp1 = static_cast<Expression*>(arguments->data[0]);
+            LLValue* vec = exp1->toElem(p)->getRVal();
+            return new DImValue(type, p->ir->CreateExtractElement(vec, idx));
+        }
         // fence instruction
         else if (fndecl->llvmInternal == LLVMfence) {
             if (arguments->dim != 1) {