Split TIntermBlock from TIntermAggregate

The new TIntermBlock node class replaces TIntermAggregate nodes with
the EOpSequence op. It represents the root node of the tree which is
a list of declarations and function definitions, and any code blocks
that can be denoted by curly braces. These include function and loop
bodies, and if-else branches.

This change enables a bunch of more compile-time type checking, and
makes the AST code easier to understand and less error-prone.

The PostProcess step that used to be done to ensure that the root node
is TIntermAggregate is removed in favor of making sure that the root
node is a TIntermBlock in the glslang.y parsing code.

Intermediate output formatting is improved to print the EOpNull error
in a clearer way.

After this patch, TIntermAggregate is still used for function
definitions, function prototypes, function parameter lists, function
calls, variable and invariant declarations and the comma (sequence)
operator.

BUG=angleproject:1490
TEST=angle_unittests, angle_end2end_tests

Change-Id: I04044affff979a11577bc1fe75d747e538b799c8
Reviewed-on: https://chromium-review.googlesource.com/393726
Commit-Queue: Olli Etuaho <oetuaho@nvidia.com>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
diff --git a/src/compiler/translator/intermOut.cpp b/src/compiler/translator/intermOut.cpp
index aed53d4..e3f9a55 100644
--- a/src/compiler/translator/intermOut.cpp
+++ b/src/compiler/translator/intermOut.cpp
@@ -48,6 +48,7 @@
     bool visitTernary(Visit visit, TIntermTernary *node) override;
     bool visitIfElse(Visit visit, TIntermIfElse *node) override;
     bool visitAggregate(Visit visit, TIntermAggregate *) override;
+    bool visitBlock(Visit visit, TIntermBlock *) override;
     bool visitLoop(Visit visit, TIntermLoop *) override;
     bool visitBranch(Visit visit, TIntermBranch *) override;
     // TODO: Add missing visit functions
@@ -374,18 +375,18 @@
 {
     TInfoSinkBase &out = sink;
 
+    OutputTreeText(out, node, mDepth);
+
     if (node->getOp() == EOpNull)
     {
         out.prefix(EPrefixError);
-        out << "node is still EOpNull!";
+        out << "node is still EOpNull!\n";
         return true;
     }
 
-    OutputTreeText(out, node, mDepth);
 
     switch (node->getOp())
     {
-      case EOpSequence:      out << "Sequence\n"; return true;
       case EOpComma:         out << "Comma\n"; return true;
       case EOpFunction:      OutputFunction(out, "Function Definition", node); break;
       case EOpFunctionCall:  OutputFunction(out, "Function Call", node); break;
@@ -457,7 +458,7 @@
         out << "Bad aggregation op";
     }
 
-    if (node->getOp() != EOpSequence && node->getOp() != EOpParameters)
+    if (node->getOp() != EOpParameters)
         out << " (" << node->getCompleteString() << ")";
 
     out << "\n";
@@ -465,6 +466,16 @@
     return true;
 }
 
+bool TOutputTraverser::visitBlock(Visit visit, TIntermBlock *node)
+{
+    TInfoSinkBase &out = sink;
+
+    OutputTreeText(out, node, mDepth);
+    out << "Code block\n";
+
+    return true;
+}
+
 bool TOutputTraverser::visitTernary(Visit visit, TIntermTernary *node)
 {
     TInfoSinkBase &out = sink;