[WebAssembly] Print instructions with type checking errors

[aheejin]

When there was a type checking error, we didn't run InstPrinter. This can be confusing because when there is an error in, say, block parameter type, InstPrinter doesn't run even if it has nothing to do with block parameter types, and all those updates to ControlFlowStack or TryStack do not happen:

llvm-project/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp

Lines 135 to 151 in c20b90a

	case WebAssembly::LOOP:
	case WebAssembly::LOOP_S:
	printAnnotation(OS, "label" + utostr(ControlFlowCounter) + ':');
	ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, true));
	return;
	case WebAssembly::BLOCK:
	case WebAssembly::BLOCK_S:
	ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false));
	return;
	case WebAssembly::TRY:
	case WebAssembly::TRY_S:
	ControlFlowStack.push_back(std::make_pair(ControlFlowCounter, false));
	TryStack.push_back(ControlFlowCounter++);
	EHInstStack.push_back(TRY);
	return;

For example,

block (i32) -> () ;; Block input parameter error
end_block         ;; Now this errors out as "End marker mismatch"

This is confusing because there is a block and the end_block is not a mismatch. Only that block has a type checking error, but that's not an end marker mismatch.

I think we can just print the instruction whether we had a type checking error or not, and this will be less confusing.

[llvmbot]

@llvm/pr-subscribers-mc

@llvm/pr-subscribers-backend-webassembly

Author: Heejin Ahn (aheejin)

Changes

When there was a type checking error, we didn't run InstPrinter. This can be confusing because when there is an error in, say, block parameter type, InstPrinter doesn't run even if it has nothing to do with block parameter types, and all those updates to ControlFlowStack or TryStack do not happen:

llvm-project/llvm/lib/Target/WebAssembly/MCTargetDesc/WebAssemblyInstPrinter.cpp

Lines 135 to 151 in c20b90a

	case WebAssembly::LOOP:
	case WebAssembly::LOOP_S:
	printAnnotation(OS, "label" + utostr(ControlFlowCounter) + ':');
	ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, true));
	return;
	case WebAssembly::BLOCK:
	case WebAssembly::BLOCK_S:
	ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false));
	return;
	case WebAssembly::TRY:
	case WebAssembly::TRY_S:
	ControlFlowStack.push_back(std::make_pair(ControlFlowCounter, false));
	TryStack.push_back(ControlFlowCounter++);
	EHInstStack.push_back(TRY);
	return;

For example,

block (i32) -> () ;; Block input parameter error
end_block         ;; Now this errors out as "End marker mismatch"

This is confusing because there is a block and the end_block is not a mismatch. Only that block has a type checking error, but that's not an end marker mismatch.

I think we can just print the instruction whether we had a type checking error or not, and this will be less confusing.

---

Full diff: https://github.com/llvm/llvm-project/pull/111067.diff

2 Files Affected:

• (modified) llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp (+2-2)
• (added) llvm/test/MC/WebAssembly/annotations-typecheck.s (+11)

diff --git a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
index 5ea6c6bc0758b9..ee8686d1166a5b 100644
--- a/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
+++ b/llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmParser.cpp
@@ -1157,8 +1157,8 @@ class WebAssemblyAsmParser final : public MCTargetAsmParser {
           Inst.setOpcode(Opc64);
         }
       }
-      if (!SkipTypeCheck && TC.typeCheck(IDLoc, Inst, Operands))
-        return true;
+      if (!SkipTypeCheck)
+        TC.typeCheck(IDLoc, Inst, Operands);
       Out.emitInstruction(Inst, getSTI());
       if (CurrentState == EndFunction) {
         onEndOfFunction(IDLoc);
diff --git a/llvm/test/MC/WebAssembly/annotations-typecheck.s b/llvm/test/MC/WebAssembly/annotations-typecheck.s
new file mode 100644
index 00000000000000..1fcdb9c0e35878
--- /dev/null
+++ b/llvm/test/MC/WebAssembly/annotations-typecheck.s
@@ -0,0 +1,11 @@
+# RUN: not llvm-mc -triple=wasm32-unknown-unknown < %s | FileCheck %s
+
+# This tests annotations are handled correctly even if there is a type checking
+# error (which are unrelated to the block annotations).
+test_annotation:
+  .functype   test_annotation () -> ()
+  block (i32) -> ()
+    drop
+# CHECK-NOT: # End marker mismatch!
+  end_block
+  end_function

[dschuff]

so this means that the assembly as a whole still fails, right?

[aheejin]

It fails because type checking fails. But at least InstPrinter and its annotation printer is not printing confusing messages.