From 100907ffa264de38bd0129ae605a624fd4e8e6ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jernej=20Krempu=C5=A1?= <jkrempus@gmail.com>
Date: Sun, 5 Aug 2012 18:51:49 +0200
Subject: [PATCH] Added pragma shufflevector.

---
 dmd2/idgen.c   |  1 +
 gen/pragma.cpp | 23 +++++++++++++++++++++++
 gen/pragma.h   |  1 +
 gen/toir.cpp   | 22 +++++++++++++++++++++-
 4 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/dmd2/idgen.c b/dmd2/idgen.c
index 2e40fbce..41f52ab7 100644
--- a/dmd2/idgen.c
+++ b/dmd2/idgen.c
@@ -272,6 +272,7 @@ Msgtable msgtable[] =
     { "no_typeinfo" },
     { "no_moduleinfo" },
     { "Alloca", "alloca" },
+    { "Shufflevector", "shufflevector" },
     { "vastart", "va_start" },
     { "vacopy", "va_copy" },
     { "vaend", "va_end" },
diff --git a/gen/pragma.cpp b/gen/pragma.cpp
index d9270c59..0681a6af 100644
--- a/gen/pragma.cpp
+++ b/gen/pragma.cpp
@@ -106,6 +106,17 @@ Pragma DtoGetPragma(Scope *sc, PragmaDeclaration *decl, std::string &arg1str)
         return LLVMalloca;
     }
 
+    // pragma(shufflevector) { funcdecl(s) }
+    else if (ident == Id::Shufflevector)
+    {
+        if (args && args->dim > 0)
+        {
+             error("takes no parameters");
+             fatal();
+        }
+        return LLVMshufflevector;
+    }
+
     // pragma(va_start) { templdecl(s) }
     else if (ident == Id::vastart)
     {
@@ -356,6 +367,18 @@ void DtoCheckPragma(PragmaDeclaration *decl, Dsymbol *s,
         }
         break;
 
+    case LLVMshufflevector:
+        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())
         {
diff --git a/gen/pragma.h b/gen/pragma.h
index cd53239a..fc4322c1 100644
--- a/gen/pragma.h
+++ b/gen/pragma.h
@@ -14,6 +14,7 @@ enum Pragma
     LLVMno_typeinfo,
     LLVMno_moduleinfo,
     LLVMalloca,
+    LLVMshufflevector,
     LLVMva_start,
     LLVMva_copy,
     LLVMva_end,
diff --git a/gen/toir.cpp b/gen/toir.cpp
index 4133cae6..37e4a200 100644
--- a/gen/toir.cpp
+++ b/gen/toir.cpp
@@ -947,8 +947,28 @@ DValue* CallExp::toElem(IRState* p)
             if (expv->getType()->toBasetype()->ty != Tint32)
                 expv = DtoCast(loc, expv, Type::tint32);
             return new DImValue(type, p->ir->CreateAlloca(LLType::getInt8Ty(gIR->context()), expv->getRVal(), ".alloca"));
+        } 
+        // shufflevector
+        else if (fndecl->llvmInternal == LLVMshufflevector) {
+            llvm::SmallVector<llvm::Constant*, 32> mask;
+            for(int i = 2, n = arguments->dim; i < n; i++){
+                Expression* exp = static_cast<Expression*>(arguments->data[i]);
+                if(exp->op != TOKint64){
+                    error("Function %s was declared with pragma shufflevector. Because of that all of its arguments except the first two must be integer literals.", f->toChars());
+                    fatal();
+                }
+                IntegerExp* iexp = static_cast<IntegerExp*>(arguments->data[i]);
+                mask.push_back(iexp->toConstElem(p));
+            } 
+            LLValue* maskVal = llvm::ConstantVector::get(mask);
+            Expression* exp1 = static_cast<Expression*>(arguments->data[0]);
+            Expression* exp2 = static_cast<Expression*>(arguments->data[1]);
+            LLValue* v1 = exp1->toElem(p)->getRVal();
+            LLValue* v2 = exp2->toElem(p)->getRVal();
+            return new DImValue(type, p->ir->CreateShuffleVector(v1, v2, maskVal));
+        } 
         // fence instruction
-        } else if (fndecl->llvmInternal == LLVMfence) {
+        else if (fndecl->llvmInternal == LLVMfence) {
             if (arguments->dim != 1) {
                 error("fence instruction expects 1 arguments");
                 return NULL;