cache visibility for all lines in trace

So far we were only doing so for the first few lines, just enough to render
one page's worth of lines. We'd have probably noticed if we collapsed some
lines after re-evaluating.

shell/trace.mu

@@ -429,6 +429,14 @@ fn render-trace screen: (addr screen), _self: (addr trace), xmin: int, ymin: int
     abort "null trace"
   }
   var y/ecx: int <- copy ymin
+  # recreate caches if necessary
+  var recreate-caches?/eax: (addr boolean) <- get self, recreate-caches?
+  compare *recreate-caches?, 0/false
+  {
+    break-if-=
+    recompute-all-visible-lines self
+    mark-lines-clean self
+  }
   clamp-cursor-to-top self, y
   var trace-ah/eax: (addr handle array trace-line) <- get self, data
   var _trace/eax: (addr array trace-line) <- lookup *trace-ah
@@ -485,7 +493,7 @@ fn render-trace screen: (addr screen), _self: (addr trace), xmin: int, ymin: int
         break $render-trace:iter
       }
       # display expanded lines
-      var display?/eax: boolean <- should-render? self, curr
+      var display?/eax: boolean <- should-render? curr
       {
         compare display?, 0/false
         break-if-=
@@ -509,7 +517,6 @@ fn render-trace screen: (addr screen), _self: (addr trace), xmin: int, ymin: int
   }
   # prevent cursor from going too far down
   clamp-cursor-to-bottom self, y, screen, xmin, ymin, xmax, ymax
-  mark-lines-clean self
   return y
 }
 
@@ -567,19 +574,34 @@ fn render-trace-line screen: (addr screen), _self: (addr trace-line), xmin: int,
   return y
 }
 
-# this is super-inefficient, string comparing every trace line
-# against every visible line on every render
-fn should-render? _self: (addr trace), _line: (addr trace-line) -> _/eax: boolean {
+fn should-render? _line: (addr trace-line) -> _/eax: boolean {
+  var line/eax: (addr trace-line) <- copy _line
+  var result/eax: (addr boolean) <- get line, visible?
+  return *result
+}
+
+# This is super-inefficient, string-comparing every trace line
+# against every visible line.
+fn recompute-all-visible-lines _self: (addr trace) {
   var self/esi: (addr trace) <- copy _self
-  # if visible? is already cached, just return it
-  var dest/edx: (addr boolean) <- get self, recreate-caches?
-  compare *dest, 0/false
+  var max-addr/edx: (addr int) <- get self, first-free
+  var trace-ah/eax: (addr handle array trace-line) <- get self, data
+  var _trace/eax: (addr array trace-line) <- lookup *trace-ah
+  var trace/esi: (addr array trace-line) <- copy _trace
+  var i/ecx: int <- copy 0
   {
-    break-if-!=
-    var line/eax: (addr trace-line) <- copy _line
-    var result/eax: (addr boolean) <- get line, visible?
-    return *result
+    compare i, *max-addr
+    break-if->=
+    var offset/ebx: (offset trace-line) <- compute-offset trace, i
+    var curr/ebx: (addr trace-line) <- index trace, offset
+    recompute-visibility _self, curr
+    i <- increment
+    loop
   }
+}
+
+fn recompute-visibility _self: (addr trace), _line: (addr trace-line) {
+  var self/esi: (addr trace) <- copy _self
   # recompute
   var candidates-ah/eax: (addr handle array trace-line) <- get self, visible
   var candidates/eax: (addr array trace-line) <- lookup *candidates-ah
@@ -597,7 +619,6 @@ fn should-render? _self: (addr trace), _line: (addr trace-line) -> _/eax: boolea
       var line/eax: (addr trace-line) <- copy _line
       var dest/eax: (addr boolean) <- get line, visible?
       copy-to *dest, 1/true
-      return 1/true
     }
     i <- increment
     loop
@@ -605,7 +626,6 @@ fn should-render? _self: (addr trace), _line: (addr trace-line) -> _/eax: boolea
   var line/eax: (addr trace-line) <- copy _line
   var dest/eax: (addr boolean) <- get line, visible?
   copy-to *dest, 0/false
-  return 0/false
 }
 
 fn clamp-cursor-to-top _self: (addr trace), _y: int {
@@ -645,7 +665,7 @@ fn clamp-cursor-to-bottom _self: (addr trace), _y: int, screen: (addr screen), x
   }
   var cursor-offset/ecx: (offset trace-line) <- compute-offset trace, cursor-line-index
   var cursor-line/ecx: (addr trace-line) <- index trace, cursor-offset
-  var display?/eax: boolean <- should-render? self, cursor-line
+  var display?/eax: boolean <- should-render? cursor-line
   {
     compare display?, 0/false
     break-if-=