[PATCH] D72308: [WebAssembly] Fix landingpad-only case in Emscripten EH

[Heejin Ahn via Phabricator via llvm-commits]

aheejin created this revision.
aheejin added a reviewer: tlively.
Herald added subscribers: llvm-commits, sunfish, hiraditya, jgravelle-google, sbc100, dschuff.
Herald added a project: LLVM.

Previously we didn't set `Changed` to true when there are only landing
pads but not invokes. This fixes it and we set `Changed` to true
whenever we have landing pads. (There can't be invokes without landing
pads, so that case is covered too)

The test case for this has to be a separate file because this pass is a
`ModulePass` and `Changed` is computed based on the whole module.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D72308

Files:
  llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
  llvm/test/CodeGen/WebAssembly/lower-em-exceptions-lpad-only.ll


Index: llvm/test/CodeGen/WebAssembly/lower-em-exceptions-lpad-only.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/WebAssembly/lower-em-exceptions-lpad-only.ll
@@ -0,0 +1,25 @@
+; RUN: opt < %s -wasm-lower-em-ehsjlj -S | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+ at _ZTIi = external constant i8*
+
+; Checks if a module that only contains a landingpad (and resume) but not an
+; invoke works correctly and does not crash.
+; CHECK-LABEL: @landingpad_only
+define void @landingpad_only() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+entry:
+  br label %cont
+
+lpad:                                             ; preds = %entry
+  %0 = landingpad { i8*, i32 }
+          catch i8* bitcast (i8** @_ZTIi to i8*)
+          catch i8* null
+  resume { i8*, i32 } %0
+
+cont:
+  ret void
+}
+
+declare i32 @__gxx_personality_v0(...)
Index: llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
+++ llvm/lib/Target/WebAssembly/WebAssemblyLowerEmscriptenEHSjLj.cpp
@@ -751,7 +751,6 @@
     auto *II = dyn_cast<InvokeInst>(BB.getTerminator());
     if (!II)
       continue;
-    Changed = true;
     LandingPads.insert(II->getLandingPadInst());
     IRB.SetInsertPoint(II);
 
@@ -831,6 +830,7 @@
     if (auto *LPI = dyn_cast<LandingPadInst>(I))
       LandingPads.insert(LPI);
   }
+  Changed = !LandingPads.empty();
 
   // Handle all the landingpad for this function together, as multiple invokes
   // may share a single lp


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D72308.236480.patch
Type: text/x-patch
Size: 1723 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20200107/ab8f39a6/attachment.bin>