wasm: Write nops for padding debug info

1 files changed, 101 insertions, 5 deletions

diff --git a/src/link/Dwarf.zig b/src/link/Dwarf.zig
index a7d2744491..a204dd91ae 100644
--- a/src/link/Dwarf.zig
+++ b/src/link/Dwarf.zig
@@ -851,6 +851,10 @@ pub fn commitDeclState(
                                 const file_pos = debug_line_sect.offset + src_fn.off;
                                 try pwriteDbgLineNops(d_sym.file, file_pos, 0, &[0]u8{}, src_fn.len);
                             },
+                            .wasm => {
+                                const wasm_file = file.cast(File.Wasm).?;
+                                writeDbgLineNopsBuffered(wasm_file.debug_line.items, src_fn.off, 0, &.{}, src_fn.len);
+                            },
                             else => unreachable,
                         }
                         // TODO Look at the free list before appending at the end.
@@ -972,9 +976,16 @@ pub fn commitDeclState(
                             mem.set(u8, debug_line.items[segment.size..], 0);
                         }
                         segment.size = needed_size;
+                        debug_line.items.len = needed_size;
                     }
                     const offset = segment.offset + src_fn.off;
-                    mem.copy(u8, debug_line.items[offset..], dbg_line_buffer.items);
+                    writeDbgLineNopsBuffered(
+                        debug_line.items,
+                        offset,
+                        prev_padding_size,
+                        dbg_line_buffer.items,
+                        next_padding_size,
+                    );
                 },
                 else => unreachable,
             }
@@ -1114,7 +1125,8 @@ fn updateDeclDebugInfoAllocation(self: *Dwarf, file: *File, atom: *Atom, len: u3
                         try pwriteDbgInfoNops(d_sym.file, file_pos, 0, &[0]u8{}, atom.len, false);
                     },
                     .wasm => {
-                        log.debug(" todo: updateDeclDebugInfoAllocation for Wasm: {d}", .{atom.len});
+                        const wasm_file = file.cast(File.Wasm).?;
+                        writeDbgInfoNopsBuffered(wasm_file.debug_info.items, atom.off, 0, &.{0}, atom.len, false);
                     },
                     else => unreachable,
                 }
@@ -1253,9 +1265,17 @@ fn writeDeclDebugInfo(self: *Dwarf, file: *File, atom: *Atom, dbg_info_buf: []co
                     mem.set(u8, debug_info.items[segment.size..], 0);
                 }
                 segment.size = needed_size;
+                debug_info.items.len = needed_size;
             }
             const offset = segment.offset + atom.off;
-            mem.copy(u8, debug_info.items[offset..], dbg_info_buf);
+            writeDbgInfoNopsBuffered(
+                debug_info.items,
+                offset,
+                prev_padding_size,
+                dbg_info_buf,
+                next_padding_size,
+                trailing_zero,
+            );
         },
         else => unreachable,
     }
@@ -1643,7 +1663,7 @@ pub fn writeDbgInfoHeader(self: *Dwarf, file: *File, module: *Module, low_pc: u6
         },
         .wasm => {
             const wasm_file = file.cast(File.Wasm).?;
-            mem.copy(u8, wasm_file.debug_info.items, di_buf.items);
+            writeDbgInfoNopsBuffered(wasm_file.debug_info.items, 0, 0, di_buf.items, jmp_amt, false);
         },
         else => unreachable,
     }
@@ -1738,6 +1758,45 @@ fn pwriteDbgLineNops(
     try file.pwritevAll(vecs[0..vec_index], offset - prev_padding_size);
 }
 
+fn writeDbgLineNopsBuffered(
+    buf: []u8,
+    offset: u32,
+    prev_padding_size: usize,
+    content: []const u8,
+    next_padding_size: usize,
+) void {
+    assert(buf.len >= content.len + prev_padding_size + next_padding_size);
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    const three_byte_nop = [3]u8{ DW.LNS.advance_pc, 0b1000_0000, 0 };
+    {
+        var padding_left = prev_padding_size;
+        if (padding_left % 2 != 0) {
+            buf[offset - padding_left ..][0..3].* = three_byte_nop;
+            padding_left -= 3;
+        }
+
+        while (padding_left > 0) : (padding_left -= 1) {
+            buf[offset - padding_left] = DW.LNS.negate_stmt;
+        }
+    }
+
+    mem.copy(u8, buf[offset..], content);
+
+    {
+        var padding_left = next_padding_size;
+        if (padding_left % 2 != 0) {
+            buf[offset + content.len + padding_left ..][0..3].* = three_byte_nop;
+            padding_left -= 3;
+        }
+
+        while (padding_left > 0) : (padding_left -= 1) {
+            buf[offset + content.len + padding_left] = DW.LNS.negate_stmt;
+        }
+    }
+}
+
 /// Writes to the file a buffer, prefixed and suffixed by the specified number of
 /// bytes of padding.
 fn pwriteDbgInfoNops(
@@ -1810,6 +1869,38 @@ fn pwriteDbgInfoNops(
     try file.pwritevAll(vecs[0..vec_index], offset - prev_padding_size);
 }
 
+fn writeDbgInfoNopsBuffered(
+    buf: []u8,
+    offset: u32,
+    prev_padding_size: usize,
+    content: []const u8,
+    next_padding_size: usize,
+    trailing_zero: bool,
+) void {
+    assert(buf.len >= content.len + prev_padding_size + next_padding_size + @boolToInt(trailing_zero));
+    const tracy = trace(@src());
+    defer tracy.end();
+
+    {
+        var padding_left = prev_padding_size;
+        while (padding_left > 0) : (padding_left -= 1) {
+            buf[offset - padding_left] = @enumToInt(AbbrevKind.pad1);
+        }
+    }
+
+    mem.copy(u8, buf[offset..], content);
+    {
+        var padding_left = next_padding_size;
+        while (padding_left > 0) : (padding_left -= 1) {
+            buf[offset + content.len + padding_left] = @enumToInt(AbbrevKind.pad1);
+        }
+    }
+
+    if (trailing_zero) {
+        buf[offset + content.len + next_padding_size] = 0;
+    }
+}
+
 pub fn writeDbgAranges(self: *Dwarf, file: *File, addr: u64, size: u64) !void {
     const target_endian = self.target.cpu.arch.endian();
     const init_len_size: usize = if (self.tag == .macho)
@@ -1909,6 +2000,11 @@ pub fn writeDbgAranges(self: *Dwarf, file: *File, addr: u64, size: u64) !void {
             const file_pos = debug_aranges_sect.offset;
             try d_sym.file.pwriteAll(di_buf.items, file_pos);
         },
+        .wasm => {
+            const wasm_file = file.cast(File.Wasm).?;
+            try wasm_file.debug_aranges.resize(wasm_file.base.allocator, needed_size);
+            mem.copy(u8, wasm_file.debug_aranges.items, di_buf.items);
+        },
         else => unreachable,
     }
 }
@@ -2030,7 +2126,7 @@ pub fn writeDbgLineHeader(self: *Dwarf, file: *File, module: *Module) !void {
         },
         .wasm => {
             const wasm_file = file.cast(File.Wasm).?;
-            mem.copy(u8, wasm_file.debug_line.items, di_buf.items);
+            writeDbgLineNopsBuffered(wasm_file.debug_line.items, 0, 0, di_buf.items, jmp_amt);
         },
         else => unreachable,
     }