[opaque pointer types] Pass value type to GetElementPtr creation.

This cleans up all GetElementPtr creation in LLVM to explicitly pass a
value type rather than deriving it from the pointer's element-type.

Differential Revision: https://reviews.llvm.org/D57173

llvm-svn: 352913
diff --git a/llvm/lib/Transforms/IPO/GlobalOpt.cpp b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
index 5080e02..7f3644b 100644
--- a/llvm/lib/Transforms/IPO/GlobalOpt.cpp
+++ b/llvm/lib/Transforms/IPO/GlobalOpt.cpp
@@ -729,7 +729,8 @@
           break;
       if (Idxs.size() == GEPI->getNumOperands()-1)
         Changed |= OptimizeAwayTrappingUsesOfValue(
-            GEPI, ConstantExpr::getGetElementPtr(nullptr, NewV, Idxs));
+            GEPI, ConstantExpr::getGetElementPtr(GEPI->getSourceElementType(),
+                                                 NewV, Idxs));
       if (GEPI->use_empty()) {
         Changed = true;
         GEPI->eraseFromParent();