DebugLocationPropagation: pass debuglocation from parent node to chil… (#6500)

This PR creates a pass to propagate debug location from parent node to child nodes which has no debug location with pre-order traversal. This is useful for compilers that use Binaryen API to generate WebAssembly modules. 

It behaves like `wasm-opt` read text format file: children are tagged with the debug info of the parent, if they have no annotation of their own.

For compilers that use Binaryen API to generate WebAssembly modules, it is a bit redundant to add debugInfo for each expression, Especially when the compiler wrap expressions. 

With this pass, compilers just need to add debugInfo for the parent node, which is more convenient.

For example:
```
(drop
  (call $voidFunc)
)
```

Without this pass, if the compiler only adds debugInfo for the wrapped expression `drop`, the `call` expression has no corresponding source code mapping in DevTools debugging, which is obviously not user-friendly.

5 files changed, 68 insertions, 0 deletions

diff --git a/test/example/debug-location-propagation.cpp b/test/example/debug-location-propagation.cpp
new file mode 100644
index 000000000..b4685e391
--- /dev/null
+++ b/test/example/debug-location-propagation.cpp
@@ -0,0 +1,47 @@
+#include <cassert>
+#include <iostream>
+
+#include <binaryen-c.h>
+#include <wasm.h>
+
+int main() {
+  BinaryenModuleRef module = BinaryenModuleCreate();
+
+  BinaryenType ii[2] = {BinaryenTypeInt32(), BinaryenTypeInt32()};
+  BinaryenType params = BinaryenTypeCreate(ii, 2);
+  BinaryenType results = BinaryenTypeNone();
+
+  BinaryenExpressionRef x = BinaryenLocalGet(module, 0, BinaryenTypeInt32()),
+                        y = BinaryenLocalGet(module, 1, BinaryenTypeInt32());
+  BinaryenExpressionRef add = BinaryenBinary(module, BinaryenAddInt32(), x, y);
+  BinaryenExpressionRef drop = BinaryenDrop(module, add);
+  BinaryenExpressionRef funcBody =
+    BinaryenBlock(module, "", &drop, 1, BinaryenTypeNone());
+
+  BinaryenFunctionRef adder =
+    BinaryenAddFunction(module, "adder", params, results, NULL, 0, funcBody);
+
+  BinaryenModuleAddDebugInfoFileName(module, "main");
+
+  BinaryenFunctionSetDebugLocation(adder, x, 0, 2, 13);
+  BinaryenFunctionSetDebugLocation(adder, drop, 0, 2, 2);
+
+  BinaryenModuleValidate(module);
+  BinaryenSetDebugInfo(true);
+  const char* runPasses[] = {"propagate-debug-locs"};
+  BinaryenModuleRunPasses(module, runPasses, 1);
+
+  auto& debugLocations = module->getFunction("adder")->debugLocations;
+  assert(debugLocations.size() == 4);
+  assert(debugLocations[x].columnNumber == 13);
+  assert(debugLocations[y].columnNumber == 13);
+  assert(debugLocations[add].columnNumber == 2);
+  assert(debugLocations[drop].columnNumber == 2);
+
+  BinaryenSetDebugInfo(false);
+  BinaryenModuleDispose(module);
+
+  std::cout << "success." << std::endl;
+
+  return 0;
+}
diff --git a/test/example/debug-location-propagation.txt b/test/example/debug-location-propagation.txt
new file mode 100644
index 000000000..b32bb74d2
--- /dev/null
+++ b/test/example/debug-location-propagation.txt
@@ -0,0 +1 @@
+success.
diff --git a/test/lit/help/wasm-opt.test b/test/lit/help/wasm-opt.test
index ff07586f2..849469178 100644
--- a/test/lit/help/wasm-opt.test
+++ b/test/lit/help/wasm-opt.test
@@ -368,6 +368,10 @@
 ;; CHECK-NEXT:   --print-stack-ir                              print out Stack IR (useful for
 ;; CHECK-NEXT:                                                 internal debugging)
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --propagate-debug-locs                        propagate debug location from
+;; CHECK-NEXT:                                                 parents or previous siblings to
+;; CHECK-NEXT:                                                 child nodes
+;; CHECK-NEXT:
 ;; CHECK-NEXT:   --propagate-globals-globally                  propagate global values to other
 ;; CHECK-NEXT:                                                 globals (useful for tests)
 ;; CHECK-NEXT:
diff --git a/test/lit/help/wasm2js.test b/test/lit/help/wasm2js.test
index 493542135..4b0330db6 100644
--- a/test/lit/help/wasm2js.test
+++ b/test/lit/help/wasm2js.test
@@ -322,6 +322,10 @@
 ;; CHECK-NEXT:   --print-stack-ir                              print out Stack IR (useful for
 ;; CHECK-NEXT:                                                 internal debugging)
 ;; CHECK-NEXT:
+;; CHECK-NEXT:   --propagate-debug-locs                        propagate debug location from
+;; CHECK-NEXT:                                                 parents or previous siblings to
+;; CHECK-NEXT:                                                 child nodes
+;; CHECK-NEXT:
 ;; CHECK-NEXT:   --propagate-globals-globally                  propagate global values to other
 ;; CHECK-NEXT:                                                 globals (useful for tests)
 ;; CHECK-NEXT:
diff --git a/test/lit/wat-kitchen-sink.wast b/test/lit/wat-kitchen-sink.wast
index 3c4c56ba6..772d3f5df 100644
--- a/test/lit/wat-kitchen-sink.wast
+++ b/test/lit/wat-kitchen-sink.wast
@@ -5235,6 +5235,13 @@
  ;; CHECK-NEXT:  (drop
  ;; CHECK-NEXT:   (i32.const 2)
  ;; CHECK-NEXT:  )
+ ;; CHECK-NEXT:  ;;@ src.cpp:30:1
+ ;; CHECK-NEXT:  (drop
+ ;; CHECK-NEXT:   (i32.add
+ ;; CHECK-NEXT:    (i32.const 100)
+ ;; CHECK-NEXT:    (i32.const 200)
+ ;; CHECK-NEXT:   )
+ ;; CHECK-NEXT:  )
  ;; CHECK-NEXT: )
  (func $source-map-propagation
   ;;@ src.cpp:10:1
@@ -5245,6 +5252,11 @@
   drop
   i32.const 2
   drop
+  i32.const 100
+  i32.const 200
+  i32.add
+  ;;@ src.cpp:30:1
+  drop
  )
 
  ;; CHECK:      (func $use-types (type $107) (param $0 (ref $s0)) (param $1 (ref $s1)) (param $2 (ref $s2)) (param $3 (ref $s3)) (param $4 (ref $s4)) (param $5 (ref $s5)) (param $6 (ref $s6)) (param $7 (ref $s7)) (param $8 (ref $s8)) (param $9 (ref $a0)) (param $10 (ref $a1)) (param $11 (ref $a2)) (param $12 (ref $a3)) (param $13 (ref $subvoid)) (param $14 (ref $submany)) (param $15 (ref $all-types))