Optimize += 1, -= 1 to ++, --.

Purely cosmetic, but easier to read.

reference/shaders/comp/cfg.comp

@@ -64,7 +64,7 @@ void test()
         }
     }
     float h;
-    for (int i = 0; i < 20; i += 1, h += 10.0)
+    for (int i = 0; i < 20; i++, h += 10.0)
     {
     }
     _11.data = h;

reference/shaders/comp/dowhile.comp

@@ -22,7 +22,7 @@ void main()
     do
     {
         idat = _28.mvp * idat;
-        i += 1;
+        i++;
     } while (i < 16);
     _52.out_data[ident] = idat;
 }

reference/shaders/comp/loop.comp

@@ -23,7 +23,7 @@ void main()
         do
         {
             k *= 2;
-            i += uint(1);
+            i++;
         } while (i < ident);
     }
     switch (k)
@@ -32,7 +32,7 @@ void main()
         {
             for (;;)
             {
-                i += uint(1);
+                i++;
                 if (i > 10u)
                 {
                     break;
@@ -58,11 +58,11 @@ void main()
     while (k < 10)
     {
         idat *= 2.0;
-        k += 1;
+        k++;
     }
-    for (uint i_1 = 0u; i_1 < 16u; i_1 += uint(1), k += 1)
+    for (uint i_1 = 0u; i_1 < 16u; i_1++, k++)
     {
-        for (uint j = 0u; j < 30u; j += uint(1))
+        for (uint j = 0u; j < 30u; j++)
         {
             idat = _24.mvp * idat;
         }
@@ -70,7 +70,7 @@ void main()
     k = 0;
     for (;;)
     {
-        k += 1;
+        k++;
         if (k > 10)
         {
             k += 2;
@@ -86,18 +86,18 @@ void main()
     k = 0;
     do
     {
-        k += 1;
+        k++;
     } while (k > 10);
     int l = 0;
     for (;;)
     {
         if (l == 5)
         {
-            l += 1;
+            l++;
             continue;
         }
         idat += vec4(1.0);
-        l += 1;
+        l++;
         continue;
     }
     _177.out_data[ident] = idat;

reference/shaders/comp/return.comp

@@ -21,7 +21,7 @@ void main()
             return;
         }
     }
-    for (int i = 0; i < 20; i += 1)
+    for (int i = 0; i < 20; i++)
     {
         if (i == 10)
         {

reference/shaders/comp/torture-loop.comp

@@ -25,7 +25,7 @@ void main()
         if (_40 < 10)
         {
             idat *= 2.0;
-            k += 1;
+            k++;
             continue;
         }
         else
@@ -33,16 +33,16 @@ void main()
             break;
         }
     }
-    for (uint i = 0u; i < 16u; i += uint(1), k += 1)
+    for (uint i = 0u; i < 16u; i++, k++)
     {
-        for (uint j = 0u; j < 30u; j += uint(1))
+        for (uint j = 0u; j < 30u; j++)
         {
             idat = _24.mvp * idat;
         }
     }
     do
     {
-        k += 1;
+        k++;
     } while (k > 10);
     _89.out_data[ident] = idat;
 }

reference/shaders/frag/for-loop-init.frag

@@ -7,16 +7,16 @@ layout(location = 0) out mediump int FragColor;
 void main()
 {
     FragColor = 15;
-    for (mediump int i = 0; i < 25; i += 1)
+    for (mediump int i = 0; i < 25; i++)
     {
         FragColor += 10;
     }
-    for (mediump int j = 4, i_1 = 1; i_1 < 30; i_1 += 1, j += 4)
+    for (mediump int j = 4, i_1 = 1; i_1 < 30; i_1++, j += 4)
     {
         FragColor += 11;
     }
     mediump int k = 0;
-    for (; k < 20; k += 1)
+    for (; k < 20; k++)
     {
         FragColor += 12;
     }
@@ -26,7 +26,7 @@ void main()
     if (k == 40)
     {
         l = 0;
-        for (; l < 40; l += 1)
+        for (; l < 40; l++)
         {
             FragColor += 13;
         }
@@ -38,12 +38,12 @@ void main()
         FragColor += l;
     }
     mediump ivec2 i_2 = ivec2(0);
-    for (; i_2.x < 10; i_2.x += 1)
+    for (; i_2.x < 10; i_2.x += 4)
     {
         FragColor += i_2.y;
     }
     mediump int o = k;
-    for (mediump int m = k; m < 40; m += 1)
+    for (mediump int m = k; m < 40; m++)
     {
         FragColor += m;
     }

shaders/frag/for-loop-init.frag

@@ -37,7 +37,7 @@ void main()
    }
 
    // Vectors cannot be loop variables
-   for (ivec2 i = ivec2(0); i.x < 10; i.x++)
+   for (ivec2 i = ivec2(0); i.x < 10; i.x += 4)
    {
       FragColor += i.y;
    }

spirv_glsl.cpp

@@ -3430,6 +3430,9 @@ bool CompilerGLSL::optimize_read_modify_write(const string &lhs, const string &r
 {
 	// Do this with strings because we have a very clear pattern we can check for and it avoids
 	// adding lots of special cases to the code emission.
+	if (rhs.size() < lhs.size() + 3)
+		return false;
+
 	auto index = rhs.find(lhs);
 	if (index != 0)
 		return false;
@@ -3439,7 +3442,14 @@ bool CompilerGLSL::optimize_read_modify_write(const string &lhs, const string &r
 	if (op != lhs.size() + 1)
 		return false;
 
-	statement(lhs, " ", rhs[op], "=", rhs.substr(lhs.size() + 2), ";");
+	char bop = rhs[op];
+	auto expr = rhs.substr(lhs.size() + 3);
+	// Try to find increments and decrements. Makes it look neater as += 1, -= 1 is fairly rare to see in real code.
+	// Find some common patterns which are equivalent.
+	if ((bop == '+' || bop == '-') && (expr == "1" || expr == "uint(1)" || expr == "1u" || expr == "int(1u)"))
+		statement(lhs, bop, bop, ";");
+	else
+		statement(lhs, " ", bop, "= ", expr, ";");
 	return true;
 }