fix Issue 7625 - inlining only works with explicit else branch

dlang · Sep 20, 2015 · f5261a2 · f5261a2
1 parent 2c94b22
commit f5261a2
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Showing 2 changed files with 96 additions and 3 deletions.
diff --git a/src/inline.d b/src/inline.d
@@ -103,7 +103,33 @@ public:
             Statement s2 = (*s.statements)[i];
             if (s2)
             {
-                s2.accept(icv);
+                /* Specifically allow:
+                 *  if (condition)
+                 *      return exp1;
+                 *  return exp2;
+                 */
+                IfStatement ifs;
+                Statement s3;
+                if ((ifs = s2.isIfStatement()) !is null &&
+                    ifs.ifbody &&
+                    ifs.ifbody.isReturnStatement() &&
+                    !ifs.elsebody &&
+                    i + 1 < s.statements.dim &&
+                    (s3 = (*s.statements)[i + 1]) !is null &&
+                    s3.isReturnStatement()
+                   )
+                {
+                    if (ifs.prm)       // if variables are declared
+                    {
+                        cost = COST_MAX;
+                        return;
+                    }
+                    expressionInlineCost(ifs.condition);
+                    ifs.ifbody.accept(this);
+                    s3.accept(this);
+                }
+                else
+                    s2.accept(icv);
                 if (tooCostly(icv.cost))
                     break;
             }
@@ -564,8 +590,45 @@ extern (C++) Expression doInline(Statement s, InlineDoState* ids)
                 Statement sx = (*s.statements)[i];
                 if (sx)
                 {
-                    Expression e = doInline(sx, ids);
-                    result = Expression.combine(result, e);
+                    /* Specifically allow:
+                     *  if (condition)
+                     *  return exp1;
+                     *  return exp2;
+                     */
+                    IfStatement ifs;
+                    Statement s3;
+                    if ((ifs = sx.isIfStatement()) !is null &&
+                        ifs.ifbody &&
+                        ifs.ifbody.isReturnStatement() &&
+                        !ifs.elsebody &&
+                        i + 1 < s.statements.dim &&
+                        (s3 = (*s.statements)[i + 1]) !is null &&
+                        s3.isReturnStatement()
+                       )
+                    {
+                        /* Rewrite as ?:
+                         */
+                        Expression econd = doInline(ifs.condition, ids);
+                        assert(econd);
+                        Expression e1 = doInline(ifs.ifbody, ids);
+                        assert(ids.foundReturn);
+                        Expression e2 = doInline(s3, ids);
+
+                        Expression e = new CondExp(econd.loc, econd, e1, e2);
+                        e.type = e1.type;
+                        if (e.type.ty == Ttuple)
+                        {
+                            e1.type = Type.tvoid;
+                            e2.type = Type.tvoid;
+                            e.type = Type.tvoid;
+                        }
+                        result = Expression.combine(result, e);
+                    }
+                    else
+                    {
+                        Expression e = doInline(sx, ids);
+                        result = Expression.combine(result, e);
+                    }
                     if (ids.foundReturn)
                         break;
                 }

diff --git a/test/runnable/inline.d b/test/runnable/inline.d
@@ -752,6 +752,35 @@ void test14975() {
 
 /**********************************/
 
+int foo7625(int v)
+{
+    return bar7625(2 * v);
+}
+
+int bar7625(int a)
+{
+    ++a;
+    if (a > 0)
+        return 1;
+    return baz(a);
+}
+
+int baz(int a)
+{
+    if (a > 0)
+        throw new Exception("a > 0");
+    return a - 1;
+}
+
+void test7625()
+{
+    int x = foo7625(1);
+    if (x != 1)
+	assert(0);
+}
+
+/**********************************/
+
 int main()
 {
     test1();
@@ -777,6 +806,7 @@ int main()
     test14754();
     test14606();
     test14975();
+    test7625();
 
     printf("Success\n");
     return 0;