From 553d5518b374730145f38689ee222762436eca8c Mon Sep 17 00:00:00 2001
From: Alexey Prokhin <alexey.prokhin@yandex.ru>
Date: Sat, 8 Jan 2011 13:01:54 +0300
Subject: [PATCH] Implemented casting of a global variable to a pointer in an
 initializer. Implemented adding to a pointer in an initializer

---
 dmd/expression.h  |  4 ++++
 dmd2/expression.h |  2 ++
 gen/toir.cpp      | 60 ++++++++++++++++++++++++++++++++++++++++++++---
 3 files changed, 63 insertions(+), 3 deletions(-)

diff --git a/dmd/expression.h b/dmd/expression.h
index 6af35e5d..4469b011 100644
--- a/dmd/expression.h
+++ b/dmd/expression.h
@@ -1065,6 +1065,7 @@ struct CallExp : UnaExp
     Expression *inlineScan(InlineScanState *iss);
 
 #if IN_LLVM
+    void cacheLvalue(IRState* p);
     DValue* toElem(IRState* irs);
 #endif
 };
@@ -1333,6 +1334,7 @@ struct CommaExp : BinExp
 #endif
 
 #if IN_LLVM
+    void cacheLvalue(IRState* p);
     DValue* toElem(IRState* irs);
 #endif
 };
@@ -1468,6 +1470,7 @@ struct AddExp : BinExp
 #endif
 
 #if IN_LLVM
+    llvm::Constant* toConstElem(IRState* p);
     DValue* toElem(IRState* irs);
 #endif
 };
@@ -1490,6 +1493,7 @@ struct MinExp : BinExp
 #endif
 
 #if IN_LLVM
+    llvm::Constant* toConstElem(IRState* p);
     DValue* toElem(IRState* irs);
 #endif
 };
diff --git a/dmd2/expression.h b/dmd2/expression.h
index 357bfc67..00929142 100644
--- a/dmd2/expression.h
+++ b/dmd2/expression.h
@@ -1567,6 +1567,7 @@ struct AddExp : BinExp
 #endif
 
 #if IN_LLVM
+    llvm::Constant *toConstElem(IRState* p);
     DValue* toElem(IRState* irs);
 #endif
 };
@@ -1589,6 +1590,7 @@ struct MinExp : BinExp
 #endif
 
 #if IN_LLVM
+    llvm::Constant *toConstElem(IRState* p);
     DValue* toElem(IRState* irs);
 #endif
 };
diff --git a/gen/toir.cpp b/gen/toir.cpp
index a58039a8..627ceaa0 100644
--- a/gen/toir.cpp
+++ b/gen/toir.cpp
@@ -644,6 +644,23 @@ static void errorOnIllegalArrayOp(Expression* base, Expression* e1, Expression*
 
 //////////////////////////////////////////////////////////////////////////////////////////
 
+LLConstant* AddExp::toConstElem(IRState* p)
+{
+    // add to pointer
+    if (e1->type->ty == Tpointer && e2->type->isintegral()) {
+        LLConstant *ptr = e1->toConstElem(p);
+        LLConstant *index = e2->toConstElem(p);
+        ptr = llvm::ConstantExpr::getGetElementPtr(ptr, &index, 1);
+        return ptr;
+    }
+
+    error("expression '%s' is not a constant", toChars());
+    fatal();
+    return NULL;
+}
+
+//////////////////////////////////////////////////////////////////////////////////////////
+
 DValue* AddExp::toElem(IRState* p)
 {
     Logger::print("AddExp::toElem: %s @ %s\n", toChars(), type->toChars());
@@ -680,6 +697,23 @@ DValue* AddExp::toElem(IRState* p)
 
 //////////////////////////////////////////////////////////////////////////////////////////
 
+LLConstant* MinExp::toConstElem(IRState* p)
+{
+    if (e1->type->ty == Tpointer && e2->type->isintegral()) {
+        LLConstant *ptr = e1->toConstElem(p);
+        LLConstant *index = e2->toConstElem(p);
+        index = llvm::ConstantExpr::getNeg(index);
+        ptr = llvm::ConstantExpr::getGetElementPtr(ptr, &index, 1);
+        return ptr;
+    }
+
+    error("expression '%s' is not a constant", toChars());
+    fatal();
+    return NULL;
+}
+
+//////////////////////////////////////////////////////////////////////////////////////////
+
 DValue* MinExp::toElem(IRState* p)
 {
     Logger::print("MinExp::toElem: %s @ %s\n", toChars(), type->toChars());
@@ -917,12 +951,30 @@ LLConstant* CastExp::toConstElem(IRState* p)
     else if (tb->ty == Tpointer && e1->type->toBasetype()->ty == Tpointer) {
         res = llvm::ConstantExpr::getBitCast(e1->toConstElem(p), lltype);
     }
+    // global variable to pointer
+    else if (tb->ty == Tpointer && e1->op == TOKvar) {
+        VarDeclaration *vd = ((VarExp*)e1)->var->isVarDeclaration();
+        assert(vd);
+        vd->codegen(Type::sir);
+        LLConstant *value = vd->ir.irGlobal ? isaConstant(vd->ir.irGlobal->value) : 0;
+        if (!value)
+           goto Lerr;
+        Type *type = vd->type->toBasetype();
+        if (type->ty == Tarray || type->ty == Tdelegate) {
+            LLConstant* idxs[2] = { DtoConstSize_t(0), DtoConstSize_t(1) };
+            value = llvm::ConstantExpr::getGetElementPtr(value, idxs, 2);
+        }
+        return DtoBitCast(value, DtoType(tb));
+    }
     else {
-        error("can not cast %s to %s at compile time", e1->type->toChars(), type->toChars());
-        return e1->toConstElem(p);
+        goto Lerr;
     }
 
     return res;
+
+Lerr:
+    error("can not cast %s to %s at compile time", e1->type->toChars(), type->toChars());
+    return e1->toConstElem(p);
 }
 
 //////////////////////////////////////////////////////////////////////////////////////////
@@ -1038,7 +1090,9 @@ LLConstant* AddrExp::toConstElem(IRState* p)
 
         // gep
         LLConstant* idxs[2] = { DtoConstSize_t(0), index };
-        LLConstant* gep = llvm::ConstantExpr::getGetElementPtr(isaConstant(vd->ir.irGlobal->value), idxs, 2);
+        LLConstant *val = isaConstant(vd->ir.irGlobal->value);
+        val = DtoBitCast(val, DtoType(vd->type->pointerTo()));
+        LLConstant* gep = llvm::ConstantExpr::getGetElementPtr(val, idxs, 2);
 
         // bitcast to requested type
         assert(type->toBasetype()->ty == Tpointer);