Fix for passing arrays by value in PPC64le (#577)

src/tcompiler.cpp

@@ -1036,7 +1036,8 @@ struct CCallingConv {
         if (all_float && n_elts <= 8) {
             *usedint += n_elts;
             if (n_elts == 1) {
-                return Argument(C_AGGREGATE_REG, t, t->type);
+                return Argument(C_AGGREGATE_REG, t,
+                                StructType::get(Type::getFloatTy(*CU->TT->ctx)));
             } else {
                 auto at = ArrayType::get(Type::getFloatTy(*CU->TT->ctx), n_elts);
                 return Argument(C_ARRAY_REG, t, at);
@@ -1045,7 +1046,8 @@ struct CCallingConv {
         if (all_double && n_elts <= 8) {
             *usedint += n_elts;
             if (n_elts == 1) {
-                return Argument(C_AGGREGATE_REG, t, t->type);
+                return Argument(C_AGGREGATE_REG, t,
+                                StructType::get(Type::getDoubleTy(*CU->TT->ctx)));
             } else {
                 auto at = ArrayType::get(Type::getDoubleTy(*CU->TT->ctx), n_elts);
                 return Argument(C_ARRAY_REG, t, at);

tests/cconv_array.t

@@ -0,0 +1,69 @@
+-- Test arrays passed (returned) by value: these are not supported by
+-- C, but Terra supports them and so has to implement them at least in
+-- a self-consistent way.
+
+local test = require("test")
+
+local function run_test_case(typ, N)
+  print("running test for " .. tostring(typ[N]))
+  local terra callee(x : typ[N])
+    escape
+      for i = 1, N do
+        emit quote
+          x[i-1] = x[i-1] + i
+        end
+      end
+    end
+    return x
+  end
+
+  local args = terralib.newlist()
+  for i = 1, N do
+    args:insert(terralib.newsymbol(typ))
+  end
+  local terra caller([args])
+    var y : typ[N]
+    escape
+      for i = 1, N do
+        emit quote
+          y[i-1] = [args[i]]
+        end
+      end
+    end
+    var z = callee(y)
+    return [(
+      function()
+        local result = terralib.newlist()
+        for i = 1, N do
+          result:insert(`y[i-1])
+        end
+        for i = 1, N do
+          result:insert(`z[i-1])
+        end
+        return result
+      end)()]
+  end
+
+  local values = terralib.newlist()
+  for i = 1, N do
+    values:insert(i * 10)
+  end
+
+  local values = terralib.newlist({unpacktuple(caller(unpack(values)))})
+
+  for i = 1, N do
+    test.eq(values[i], i*10)
+  end
+  for i = N+1, 2*N do
+    test.eq(values[i], (i-N)*11)
+  end
+end
+
+for N = 0, 11 do
+  run_test_case(int8, N)
+end
+for _, typ in ipairs({int16, int32, int64, float, double}) do
+  for N = 0, 32 do
+    run_test_case(typ, N)
+  end
+end