wasm-decompile: use symbols from linking section for names. (#1318)

This allows wasm .o files to have more readable names, or even final
linked modules if the linking information is preserved (with e.g.
--emit-relocs in LLD).

This is implemented as part of the WABT IR representation, so
benefits wasm2wat as well.

Named obtained this way are only set for functions if the function
doesn't also have a name in the name section, but is preferred over
the export name if there is one.

1 files changed, 116 insertions, 0 deletions

diff --git a/test/decompile/names.txt b/test/decompile/names.txt
new file mode 100644
index 00000000..f390b891
--- /dev/null
+++ b/test/decompile/names.txt
@@ -0,0 +1,116 @@
+;;; TOOL: run-gen-wasm-decompile
+;; NOTE: same test as in test/binary/names.txt
+magic
+version
+section(TYPE) {
+  count[2]
+  function params[0] results[1] i32
+  function params[0] results[0]
+}
+section(FUNCTION) {
+  count[4]
+  type[0]
+  type[1]
+  type[1]
+  type[1]
+}
+section(MEMORY) {
+  count[1]
+  has_max[0]
+  initial[0]
+}
+section(GLOBAL) {
+  count[2]
+  ;; This has both a sym and export name, prefer sym.
+  type[i32] mut[0] init_expr[i32.const 0 end]
+  ;; This only has an export name.
+  type[i32] mut[0] init_expr[i32.const 0 end]
+}
+section(EXPORT) {
+  count[5]
+  str("F1_EXPORT") func_kind func[1]
+  str("F2_EXPORT") func_kind func[2]
+  str("F3_EXPORT") func_kind func[3]
+  str("G0_EXPORT") global_kind global[0]
+  str("G1_EXPORT") global_kind global[1]
+}
+section(CODE) {
+  count[4]
+  ;; Test name section.
+  func {
+    locals[decl_count[1] i32_count[1] i32]
+    get_local 0
+  }
+  ;; Test naming priorities
+  ;; If there's a name section name, prefer that over sym/export.
+  func { locals[0] }
+  ;; If there's no name section name, prefer sym over export.
+  func { locals[0] }
+  ;; If there's only export, use that.
+  func { locals[0] }
+}
+section(DATA) {
+  count[2]
+  ;; These can only be named thru symbols.
+  memory_index[0]
+  offset[i32.const 0 end]
+  data[str("Hello, World!")]
+  memory_index[0]
+  offset[i32.const 10 end]
+  data[str("bar")]
+}
+section("name") {
+  section(NAME_MODULE) {
+    str("M0")
+  }
+  section(NAME_FUNCTION) {
+    func_count[2]
+    index[0]
+    str("F0")
+    index[1]
+    str("F1_NS")
+  }
+  section(NAME_LOCALS) {
+    func_count[1]
+    index[0]
+    local_count[1]
+    index[0]
+    str("L0")
+  }
+}
+section("linking") {
+  metadata_version[2]
+  section(LINKING_SYMBOL_TABLE) {
+    num_symbols[5]
+    type[0] flags[1] index[1] str("F1_SYM")
+    type[0] flags[1] index[2] str("F2_SYM")
+    type[2] flags[1] index[0] str("G0_SYM")
+
+    type[1] flags[4] str("D0_SYM") segment[0] offset[0] size[1]
+    type[1] flags[4] str("D1_SYM") segment[1] offset[0] size[1]
+  }
+}
+(;; STDOUT ;;;
+memory M_a(initial: 0, max: 0);
+
+global G0_SYM:int = 0;
+export global G1_EXPORT:int = 0;
+
+data D0_SYM(offset: 0) = "Hello, World!";
+data D1_SYM(offset: 10) = "bar";
+
+function F0():int {
+  var L0:int;
+  return L0;
+}
+
+function F1_NS() {
+}
+
+function F2_SYM() {
+}
+
+export function F3_EXPORT() {
+}
+
+;;; STDOUT ;;)