fix several debug info bugs

lib/std/Build/Fuzz/WebServer.zig

@@ -634,10 +634,28 @@ fn prepareTables(
     const pcs = header.pcAddrs();
     const source_locations = try gpa.alloc(Coverage.SourceLocation, pcs.len);
     errdefer gpa.free(source_locations);
-    debug_info.resolveAddresses(gpa, pcs, source_locations) catch |err| {
+
+    // Unfortunately the PCs array that LLVM gives us from the 8-bit PC
+    // counters feature is not sorted.
+    var sorted_pcs: std.MultiArrayList(struct { pc: u64, index: u32, sl: Coverage.SourceLocation }) = .{};
+    defer sorted_pcs.deinit(gpa);
+    try sorted_pcs.resize(gpa, pcs.len);
+    @memcpy(sorted_pcs.items(.pc), pcs);
+    for (sorted_pcs.items(.index), 0..) |*v, i| v.* = @intCast(i);
+    sorted_pcs.sortUnstable(struct {
+        addrs: []const u64,
+
+        pub fn lessThan(ctx: @This(), a_index: usize, b_index: usize) bool {
+            return ctx.addrs[a_index] < ctx.addrs[b_index];
+        }
+    }{ .addrs = sorted_pcs.items(.pc) });
+
+    debug_info.resolveAddresses(gpa, sorted_pcs.items(.pc), sorted_pcs.items(.sl)) catch |err| {
         log.err("failed to resolve addresses to source locations: {s}", .{@errorName(err)});
         return error.AlreadyReported;
     };
+
+    for (sorted_pcs.items(.index), sorted_pcs.items(.sl)) |i, sl| source_locations[i] = sl;
     gop.value_ptr.source_locations = source_locations;
 
     ws.coverage_condition.broadcast();
@@ -664,8 +682,8 @@ fn addEntryPoint(ws: *WebServer, coverage_id: u64, addr: u64) error{ AlreadyRepo
     if (false) {
         const sl = coverage_map.source_locations[index];
         const file_name = coverage_map.coverage.stringAt(coverage_map.coverage.fileAt(sl.file).basename);
-        log.debug("server found entry point {s}:{d}:{d}", .{
-            file_name, sl.line, sl.column,
+        log.debug("server found entry point for 0x{x} at {s}:{d}:{d}", .{
+            addr, file_name, sl.line, sl.column,
         });
     }
     const gpa = ws.gpa;

lib/std/debug/Coverage.zig

@@ -145,60 +145,64 @@ pub const ResolveAddressesDwarfError = Dwarf.ScanError;
 pub fn resolveAddressesDwarf(
     cov: *Coverage,
     gpa: Allocator,
+    /// Asserts the addresses are in ascending order.
     sorted_pc_addrs: []const u64,
     /// Asserts its length equals length of `sorted_pc_addrs`.
     output: []SourceLocation,
     d: *Dwarf,
 ) ResolveAddressesDwarfError!void {
     assert(sorted_pc_addrs.len == output.len);
-    assert(d.compile_units_sorted);
+    assert(d.ranges.items.len != 0); // call `populateRanges` first.
 
-    var cu_i: usize = 0;
-    var line_table_i: usize = 0;
-    var cu: *Dwarf.CompileUnit = &d.compile_unit_list.items[0];
-    var range = cu.pc_range.?;
+    var range_i: usize = 0;
+    var range: *std.debug.Dwarf.Range = &d.ranges.items[0];
+    var line_table_i: usize = undefined;
+    var prev_pc: u64 = 0;
+    var prev_cu: ?*std.debug.Dwarf.CompileUnit = null;
     // Protects directories and files tables from other threads.
     cov.mutex.lock();
     defer cov.mutex.unlock();
     next_pc: for (sorted_pc_addrs, output) |pc, *out| {
+        assert(pc >= prev_pc);
+        prev_pc = pc;
+
         while (pc >= range.end) {
-            cu_i += 1;
-            if (cu_i >= d.compile_unit_list.items.len) {
+            range_i += 1;
+            if (range_i >= d.ranges.items.len) {
                 out.* = SourceLocation.invalid;
                 continue :next_pc;
             }
-            cu = &d.compile_unit_list.items[cu_i];
-            line_table_i = 0;
-            range = cu.pc_range orelse {
-                out.* = SourceLocation.invalid;
-                continue :next_pc;
-            };
+            range = &d.ranges.items[range_i];
         }
         if (pc < range.start) {
             out.* = SourceLocation.invalid;
             continue :next_pc;
         }
-        if (line_table_i == 0) {
-            line_table_i = 1;
-            cov.mutex.unlock();
-            defer cov.mutex.lock();
-            d.populateSrcLocCache(gpa, cu) catch |err| switch (err) {
-                error.MissingDebugInfo, error.InvalidDebugInfo => {
-                    out.* = SourceLocation.invalid;
-                    cu_i += 1;
-                    if (cu_i < d.compile_unit_list.items.len) {
-                        cu = &d.compile_unit_list.items[cu_i];
-                        line_table_i = 0;
-                        if (cu.pc_range) |r| range = r;
-                    }
-                    continue :next_pc;
-                },
-                else => |e| return e,
-            };
+        const cu = &d.compile_unit_list.items[range.compile_unit_index];
+        if (cu != prev_cu) {
+            prev_cu = cu;
+            if (cu.src_loc_cache == null) {
+                cov.mutex.unlock();
+                defer cov.mutex.lock();
+                d.populateSrcLocCache(gpa, cu) catch |err| switch (err) {
+                    error.MissingDebugInfo, error.InvalidDebugInfo => {
+                        out.* = SourceLocation.invalid;
+                        continue :next_pc;
+                    },
+                    else => |e| return e,
+                };
+            }
+            const slc = &cu.src_loc_cache.?;
+            const table_addrs = slc.line_table.keys();
+            line_table_i = std.sort.upperBound(u64, table_addrs, pc, struct {
+                fn order(context: u64, item: u64) std.math.Order {
+                    return std.math.order(item, context);
+                }
+            }.order);
         }
         const slc = &cu.src_loc_cache.?;
         const table_addrs = slc.line_table.keys();
-        while (line_table_i < table_addrs.len and table_addrs[line_table_i] < pc) line_table_i += 1;
+        while (line_table_i < table_addrs.len and table_addrs[line_table_i] <= pc) line_table_i += 1;
 
         const entry = slc.line_table.values()[line_table_i - 1];
         const corrected_file_index = entry.file - @intFromBool(slc.version < 5);