Rewriter: remove useless braces in a few more cases (#61)

Curly braces can be removed in this case:
  if (x) y else { break; }

The previous optimization missed this case where there's a single (non-expression) statement in a block.

src/rewriter.fs

@@ -186,7 +186,9 @@ let private simplifyStmt = function
                let expr = List.reduce (fun acc x -> FunCall(Var ",", [acc;x])) (li@[e])
                Jump(JumpKeyword.Return, Some expr)
         else
-            Block (squeezeDeclarations b)
+            match squeezeDeclarations b with
+            | [stmt] -> stmt
+            | stmts -> Block stmts
     | Decl (ty, li) -> Decl (rwType ty, declsNotToInline li)
     | ForD((ty, d), cond, inc, body) -> ForD((rwType ty, declsNotToInline d), cond, inc, body)
     // FIXME: properly handle booleans

tests/commands.txt

@@ -6,6 +6,10 @@
 --no-renaming --format js -o tests/real/disco.expected tests/real/disco.frag
 --no-renaming --format nasm -o tests/real/leizex.expected tests/real/leizex.frag
 
+# Unit tests
+
+--no-renaming --format c-variables -o tests/unit/blocks.expected tests/unit/blocks.frag
+
 # Partial renaming tests
 
 --no-renaming --format c-variables -o tests/unit/function_comma.expected tests/unit/function_comma.frag

tests/real/yx_long_way_from_home.frag.expected

@@ -157,31 +157,29 @@ const char *yx_long_way_from_home_frag =
        "if(d(v,m,a,p,t))"
          "{"
            "float k=1.;"
-           "vec3 h=vec3(1);"
+           "vec3 b=vec3(1);"
            "if(f==1)"
-             "h=vec3(.7);"
+             "b=vec3(.7);"
            "k*=k;"
            "{"
              "v=a+p*.002;"
-             "vec3 S=reflect(m,p),u=e(p,1.);"
-             "m=normalize(mix(S,u,k));"
-             "r*=h;"
+             "vec3 h=reflect(m,p),u=e(p,1.);"
+             "m=normalize(mix(h,u,k));"
+             "r*=b;"
            "}"
-           "vec3 u=d(y,n);"
-           "float S=dot(p,u);"
-           "vec3 B,b;"
-           "float R;"
-           "if(S>0.&&!d(a+p*.002,u,B,b,R))"
-             "o+=r*S*c;"
+           "vec3 h=d(y,n);"
+           "float u=dot(p,h);"
+           "vec3 S,R;"
+           "float B;"
+           "if(u>0.&&!d(a+p*.002,h,S,R,B))"
+             "o+=r*u*c;"
            "i=s(i.y);"
          "}"
        "else"
          " if(abs(t)>.1)"
            "return o+l(m)*r;"
          "else"
-           "{"
-             "break;"
-           "}"
+           " break;"
      "}"
    "return vec3(0);"
  "}"

tests/unit/blocks.expected

@@ -0,0 +1,52 @@
+/* File generated with Shader Minifier 1.1.6
+ * http://www.ctrl-alt-test.fr
+ */
+#ifndef BLOCKS_EXPECTED_
+# define BLOCKS_EXPECTED_
+
+const char *blocks_frag =
+ "float test_if()"
+ "{"
+   "int foo=2;"
+   "float bar;"
+   "if(foo==2)"
+     "foo++;"
+   "if(foo<5)"
+     "if(foo==3)"
+       "bar=.2;"
+     "else"
+       " bar=.3;"
+   "else"
+     " bar=.4;"
+   "return bar;"
+ "}"
+ "int k=5;"
+ "float test_for()"
+ "{"
+   "int foo=2,n=0;"
+   "for(int i=0;i<4;i++)"
+     "foo+=i;"
+   "for(foo++;n<4;n++)"
+     "{"
+       "int k=n-1;"
+       "foo+=k;"
+     "}"
+   "return 1./float(k);"
+ "}"
+ "int test_block()"
+ "{"
+   "if(k==0)"
+     ";"
+   "for(int i=0;i<2;i++)"
+     "if(k==1)"
+       "return k++,2;"
+     "else"
+       " break;"
+ "}"
+ "void main()"
+ "{"
+   "float a=test_if(),b=test_for();"
+   "gl_FragColor=vec4(.2,a,b,0.);"
+ "}";
+
+#endif // BLOCKS_EXPECTED_

tests/unit/blocks.frag

@@ -30,6 +30,15 @@ float test_for()
   return 1. / float(k);
 }
 
+int test_block()
+{
+  {}
+  {if (k == 0) {} else {}}
+  for (int i = 0; i < 2; i++)
+  {
+    if (k == 1) {k++; return 2;} else {break;}
+  }
+}
 
 void main()
 {