Merge pull request #12837 from topolarity/err-ret-trace-improvements-1923

stage2: Pop error trace frames for handled errors (#1923)

Author: andrewrk

lib/std/builtin.zig

@@ -869,8 +869,10 @@ pub noinline fn returnError(st: *StackTrace) void {
 }
 
 pub inline fn addErrRetTraceAddr(st: *StackTrace, addr: usize) void {
-    st.instruction_addresses[st.index & (st.instruction_addresses.len - 1)] = addr;
-    st.index +%= 1;
+    if (st.index < st.instruction_addresses.len)
+        st.instruction_addresses[st.index] = addr;
+
+    st.index += 1;
 }
 
 const std = @import("std.zig");

lib/std/debug.zig

@@ -411,6 +411,14 @@ pub fn writeStackTrace(
         const return_address = stack_trace.instruction_addresses[frame_index];
         try printSourceAtAddress(debug_info, out_stream, return_address - 1, tty_config);
     }
+
+    if (stack_trace.index > stack_trace.instruction_addresses.len) {
+        const dropped_frames = stack_trace.index - stack_trace.instruction_addresses.len;
+
+        tty_config.setColor(out_stream, .Bold);
+        try out_stream.print("({d} additional stack frames skipped...)\n", .{dropped_frames});
+        tty_config.setColor(out_stream, .Reset);
+    }
 }
 
 pub const StackIterator = struct {

src/Air.zig

@@ -733,6 +733,10 @@ pub const Inst = struct {
         /// Uses the `ty_op` field.
         addrspace_cast,
 
+        /// Saves the error return trace index, if any. Otherwise, returns 0.
+        /// Uses the `ty_pl` field.
+        save_err_return_trace_index,
+
         pub fn fromCmpOp(op: std.math.CompareOperator, optimized: bool) Tag {
             switch (op) {
                 .lt => return if (optimized) .cmp_lt_optimized else .cmp_lt,
@@ -1179,6 +1183,7 @@ pub fn typeOfIndex(air: Air, inst: Air.Inst.Index) Type {
         .slice_len,
         .ret_addr,
         .frame_addr,
+        .save_err_return_trace_index,
         => return Type.usize,
 
         .wasm_memory_grow => return Type.i32,