[PATCH] D115748: [WebAssembly] Fix typechecking for else MCInst

[Paulo Matos via Phabricator via llvm-commits]

pmatos created this revision.
pmatos added a reviewer: aardappel.
Herald added subscribers: ecnelises, sunfish, hiraditya, jgravelle-google, dschuff.
pmatos requested review of this revision.
Herald added subscribers: llvm-commits, aheejin.
Herald added a project: LLVM.

When hitting an else clause the type Stack should be reset to as it was at the start of the if, without taking into account the Type inserted into the Stack during the then branch of the if.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D115748

Files:
  llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp
  llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.h
  llvm/test/MC/WebAssembly/typechecking-else.s


Index: llvm/test/MC/WebAssembly/typechecking-else.s
===================================================================
--- /dev/null
+++ llvm/test/MC/WebAssembly/typechecking-else.s
@@ -0,0 +1,21 @@
+# Check that it converts to .o without errors
+# RUN: llvm-mc -triple=wasm32-unknown-unknown -filetype=obj -mattr=+reference-types < %s
+
+objects:
+    .tabletype objects,externref
+
+handle_value:
+    .hidden handle_value
+    .globl handle_value
+    .type handle_value, at function
+    .functype       handle_value (i32) -> (externref)
+    local.get 0
+    i32.const -1
+    i32.eq
+    if externref
+    ref.null_extern
+    else
+    local.get 0
+    table.get objects
+    end_if
+    end_function
Index: llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.h
===================================================================
--- llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.h
+++ llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.h
@@ -39,7 +39,7 @@
   bool typeError(SMLoc ErrorLoc, const Twine &Msg);
   bool popType(SMLoc ErrorLoc, Optional<wasm::ValType> EVT);
   bool getLocal(SMLoc ErrorLoc, const MCInst &Inst, wasm::ValType &Type);
-  bool checkEnd(SMLoc ErrorLoc);
+  bool checkEnd(SMLoc ErrorLoc, bool PopVals = false);
   bool checkSig(SMLoc ErrorLoc, const wasm::WasmSignature &Sig);
   bool getSymRef(SMLoc ErrorLoc, const MCInst &Inst,
                  const MCSymbolRefExpr *&SymRef);
Index: llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp
+++ llvm/lib/Target/WebAssembly/AsmParser/WebAssemblyAsmTypeCheck.cpp
@@ -112,9 +112,18 @@
   return false;
 }
 
-bool WebAssemblyAsmTypeCheck::checkEnd(SMLoc ErrorLoc) {
+bool WebAssemblyAsmTypeCheck::checkEnd(SMLoc ErrorLoc, bool PopVals) {
   if (LastSig.Returns.size() > Stack.size())
     return typeError(ErrorLoc, "end: insufficient values on the type stack");
+  
+  if (PopVals) {
+    for (auto VT : llvm::reverse(LastSig.Returns)) {
+      if (popType(ErrorLoc, VT)) 
+        return true;
+    }
+    return false;
+  }
+  
   for (size_t i = 0; i < LastSig.Returns.size(); i++) {
     auto EVT = LastSig.Returns[i];
     auto PVT = Stack[Stack.size() - LastSig.Returns.size() + i];
@@ -221,7 +230,7 @@
       return true;
   } else if (Name == "end_block" || Name == "end_loop" || Name == "end_if" ||
              Name == "else" || Name == "end_try") {
-    if (checkEnd(ErrorLoc))
+    if (checkEnd(ErrorLoc, Name == "else"))
       return true;
     if (Name == "end_block")
       Unreachable = false;


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