shader: Bug fix: Wrong local variable index in a block in an entry point

internal/shader/shader.go

@@ -677,6 +677,15 @@ func (cs *compileState) parseBlock(outer *block, fname string, stmts []ast.Stmt,
 		for b := outer; b != nil; b = b.outer {
 			offset += len(b.vars)
 		}
+		if fname == cs.vertexEntry {
+			offset -= len(cs.ir.Attributes)
+			offset-- // position
+			offset -= len(cs.ir.Varyings)
+		}
+		if fname == cs.fragmentEntry {
+			offset-- // position
+			offset -= len(cs.ir.Varyings)
+		}
 	}
 
 	block := &block{

internal/shader/testdata/for5.expected.vs

@@ -0,0 +1,35 @@
+uniform float U0;
+uniform float U1;
+uniform float U2;
+attribute vec2 A0;
+
+void F0(in int l0, out int l1);
+
+void F0(in int l0, out int l1) {
+	l1 = l0;
+	return;
+}
+
+void main(void) {
+	int l0 = 0;
+	int l2 = 0;
+	l0 = 0;
+	for (int l1 = 0; l1 < 10; l1++) {
+		int l2 = 0;
+		int l3 = 0;
+		F0(l1, l2);
+		l3 = l2;
+		l0 = (l0) + (l3);
+		for (int l4 = 0; l4 < 10; l4++) {
+			int l5 = 0;
+			int l6 = 0;
+			F0(l4, l5);
+			l6 = l5;
+			l0 = (l0) + (l6);
+		}
+	}
+	l2 = 0;
+	l0 = (l0) + (l2);
+	gl_Position = vec4(l0);
+	return;
+}

internal/shader/testdata/for5.go

@@ -0,0 +1,26 @@
+package main
+
+var (
+	U0 float
+	U1 float
+	U2 float
+)
+
+func Ident(x int) int {
+	return x
+}
+
+func Vertex(pos vec2) vec4 {
+	sum := 0
+	for i := 0; i < 10; i++ {
+		x := Ident(i)
+		sum += x
+		for j := 0; j < 10; j++ {
+			x := Ident(j)
+			sum += x
+		}
+	}
+	y := 0
+	sum += y
+	return vec4(sum)
+}