fix(timings): unit index is not assigned sequentially

Author: weihanglo

src/cargo/core/compiler/timings/timings.js

@@ -22,6 +22,7 @@ let UNIT_COORDS = {};
 // Map of unit index to the index it was unlocked by.
 let REVERSE_UNIT_DEPS = {};
 let REVERSE_UNIT_RMETA_DEPS = {};
+let UNIT_BY_INDEX = {};
 
 const MIN_GRAPH_WIDTH = 200;
 const MAX_GRAPH_WIDTH = 4096;
@@ -76,13 +77,13 @@ const DEP_LINE_COLOR = getCssColor('--canvas-dep-line');
 const DEP_LINE_HIGHLIGHTED_COLOR = getCssColor('--canvas-dep-line-highlighted');
 const CPU_COLOR = getCssColor('--canvas-cpu');
 
-for (let n=0; n<UNIT_DATA.length; n++) {
-  let unit = UNIT_DATA[n];
+for (const unit of UNIT_DATA) {
+  UNIT_BY_INDEX[unit.i] = unit;
   for (let unblocked of unit.unblocked_units) {
-    REVERSE_UNIT_DEPS[unblocked] = n;
+    REVERSE_UNIT_DEPS[unblocked] = unit.i;
   }
   for (let unblocked of unit.unblocked_rmeta_units) {
-    REVERSE_UNIT_RMETA_DEPS[unblocked] = n;
+    REVERSE_UNIT_RMETA_DEPS[unblocked] = unit.i;
   }
 }
 
@@ -318,7 +319,7 @@ function get_codegen_section_x(sections) {
 
 // Draws lines from the given unit to the units it unlocks.
 function draw_dep_lines(ctx, unit_idx, highlighted) {
-  const unit = UNIT_DATA[unit_idx];
+  const unit = UNIT_BY_INDEX[unit_idx];
   const {x, y, sections} = UNIT_COORDS[unit_idx];
   ctx.save();
   for (const unblocked of unit.unblocked_units) {