Don't skip entries with a zero address

While these are typically invalid in executables, they are commonly found in
object files.

The extra parsing is a signifcant slowdown when parsing all inlined
functions, but that isn't something that is done in practice.

 name                                        before ns/iter  after ns/iter  diff ns/iter  diff %  speedup
 context_new_and_query_location_rc           2,934,098       2,974,950            40,852   1.39%   x 0.99
 context_new_and_query_location_slice        1,095,621       1,088,575            -7,046  -0.64%   x 1.01
 context_new_and_query_with_functions_rc     3,015,372       2,937,087           -78,285  -2.60%   x 1.03
 context_new_and_query_with_functions_slice  1,113,536       1,106,034            -7,502  -0.67%   x 1.01
 context_new_parse_functions_rc              24,044,280      24,155,066          110,786   0.46%   x 1.00
 context_new_parse_functions_slice           18,419,484      18,677,813          258,329   1.40%   x 0.99
 context_new_parse_inlined_functions_rc      53,407,830      67,349,900       13,942,070  26.10%   x 0.79
 context_new_parse_inlined_functions_slice   40,770,422      52,019,140       11,248,718  27.59%   x 0.78
 context_new_parse_lines_rc                  12,197,122      12,437,465          240,343   1.97%   x 0.98
 context_new_parse_lines_slice               7,708,400       8,106,853           398,453   5.17%   x 0.95
 context_new_rc                              2,451,931       2,487,168            35,237   1.44%   x 0.99
 context_new_slice                           686,375         679,285              -7,090  -1.03%   x 1.01
 context_query_location_rc                   1,024,982       1,041,449            16,467   1.61%   x 0.98
 context_query_location_slice                1,008,474       1,024,442            15,968   1.58%   x 0.98
 context_query_with_functions_rc             2,973,875       3,037,333            63,458   2.13%   x 0.98
 context_query_with_functions_slice          2,670,629       2,663,918            -6,711  -0.25%   x 1.00

src/lib.rs

@@ -231,7 +231,7 @@ impl<R: gimli::Reader> Context<R> {
                     }
                 }
 
-                ranges.for_each_range(&sections, &dw_unit, true, |range| {
+                ranges.for_each_range(&sections, &dw_unit, |range| {
                     unit_ranges.push(UnitRange {
                         range,
                         unit_id,
@@ -493,13 +493,11 @@ where
                             let end = row.address();
                             let mut rows = Vec::new();
                             mem::swap(&mut rows, &mut sequence_rows);
-                            if start != 0 {
-                                sequences.push(LineSequence {
-                                    start,
-                                    end,
-                                    rows: rows.into_boxed_slice(),
-                                });
-                            }
+                            sequences.push(LineSequence {
+                                start,
+                                end,
+                                rows: rows.into_boxed_slice(),
+                            });
                         }
                         continue;
                     }
@@ -815,7 +813,7 @@ impl<R: gimli::Reader> Functions<R> {
                     }
 
                     let function_index = functions.len();
-                    if ranges.for_each_range(sections, unit, false, |range| {
+                    if ranges.for_each_range(sections, unit, |range| {
                         addresses.push(FunctionAddress {
                             range,
                             function: function_index,
@@ -1114,7 +1112,7 @@ impl<R: gimli::Reader> InlinedFunction<R> {
             call_column,
         });
 
-        ranges.for_each_range(sections, unit, false, |range| {
+        ranges.for_each_range(sections, unit, |range| {
             inlined_addresses.push(InlinedFunctionAddress {
                 range,
                 call_depth: inlined_depth,
@@ -1158,15 +1156,11 @@ impl<R: gimli::Reader> RangeAttributes<R> {
         &self,
         sections: &gimli::Dwarf<R>,
         unit: &gimli::Unit<R>,
-        allow_at_zero: bool,
         mut f: F,
     ) -> Result<bool, Error> {
         let mut added_any = false;
         let mut add_range = |range: gimli::Range| {
-            // Ignore invalid DWARF so that a query of 0 does not give
-            // a long list of matches.
-            // TODO: don't ignore if there is a section at this address
-            if (allow_at_zero || range.begin != 0) && range.begin < range.end {
+            if range.begin < range.end {
                 f(range);
                 added_any = true
             }

tests/correctness.rs

@@ -80,22 +80,12 @@ fn test_function() {
     println!("x");
 }
 
-#[test]
-fn zero_sequence() {
-    let map = find_debuginfo();
-    let file = &object::File::parse(&*map).unwrap();
-    let ctx = Context::new(file).unwrap();
-    for probe in 0..10 {
-        assert!(ctx.find_location(probe).unwrap().is_none());
-    }
-}
-
 #[test]
 fn zero_function() {
     let map = find_debuginfo();
     let file = &object::File::parse(&*map).unwrap();
     let ctx = Context::new(file).unwrap();
     for probe in 0..10 {
-        assert!(ctx.find_frames(probe).unwrap().next().unwrap().is_none());
+        assert!(ctx.find_frames(probe).unwrap().count().unwrap() < 10);
     }
 }