[PATCH] D65246: [WebAssembly] Do not emit tail calls with return type mismatch

[Thomas Lively via Phabricator via llvm-commits]

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

return_call and return_call_indirect are only valid if the return
types of the callee and caller match. We were previously not enforcing
that, which was producing invalid modules.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D65246

Files:
  llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
  llvm/test/CodeGen/WebAssembly/tailcall.ll


Index: llvm/test/CodeGen/WebAssembly/tailcall.ll
===================================================================
--- llvm/test/CodeGen/WebAssembly/tailcall.ll
+++ llvm/test/CodeGen/WebAssembly/tailcall.ll
@@ -124,6 +124,23 @@
   ret i32 %v
 }
 
+; CHECK-LABEL: mismatched_return_void:
+; CHECK: i32.call $drop=, baz, $pop{{[0-9]+}}, $pop{{[0-9]+}}, $pop{{[0-9]+}}{{$}}
+; CHECK: return{{$}}
+define void @mismatched_return_void() {
+  %v = tail call i32 @baz(i32 0, i32 42, i32 6)
+  ret void
+}
+
+; CHECK-LABEL: mismatched_return_f32:
+; CHECK: i32.call $drop=, baz, $pop{{[0-9]+}}, $pop{{[0-9]+}}, $pop{{[0-9]+}}{{$}}
+; CHECK: f32.const $push[[L:[0-9]+]]=, 0x1p0{{$}}
+; CHECK: return $pop[[L]]{{$}}
+define float @mismatched_return_f32() {
+  %v = tail call i32 @baz(i32 0, i32 42, i32 6)
+  ret float 1.
+}
+
 ; CHECK-LABEL: mismatched_byval:
 ; CHECK: i32.store
 ; CHECK: return_call quux, $pop{{[0-9]+}}{{$}}
Index: llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
===================================================================
--- llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
+++ llvm/lib/Target/WebAssembly/WebAssemblyISelLowering.cpp
@@ -644,13 +644,31 @@
   if (CLI.IsPatchPoint)
     fail(DL, DAG, "WebAssembly doesn't support patch point yet");
 
-  // Fail if tail calls are required but not enabled
-  if (!Subtarget->hasTailCall()) {
-    if ((CallConv == CallingConv::Fast && CLI.IsTailCall &&
-         MF.getTarget().Options.GuaranteedTailCallOpt) ||
-        (CLI.CS && CLI.CS.isMustTailCall()))
-      fail(DL, DAG, "WebAssembly 'tail-call' feature not enabled");
-    CLI.IsTailCall = false;
+  if (CLI.IsTailCall) {
+    bool MustTail = (CallConv == CallingConv::Fast && CLI.IsTailCall &&
+                     MF.getTarget().Options.GuaranteedTailCallOpt) ||
+                    (CLI.CS && CLI.CS.isMustTailCall());
+    if (Subtarget->hasTailCall()) {
+      // Do not tail call unless caller and callee return types match
+      const Function &F = MF.getFunction();
+      const TargetMachine &TM = getTargetMachine();
+      Type *RetTy = F.getReturnType();
+      SmallVector<MVT, 4> CallerRetTys;
+      SmallVector<MVT, 4> CalleeRetTys;
+      computeLegalValueVTs(F, TM, RetTy, CallerRetTys);
+      computeLegalValueVTs(F, TM, CLI.RetTy, CalleeRetTys);
+      bool TypesMatch = CallerRetTys.size() == CalleeRetTys.size() &&
+                        std::equal(CallerRetTys.begin(), CallerRetTys.end(),
+                                   CalleeRetTys.begin());
+      if (!TypesMatch) {
+        assert(!MustTail);
+        CLI.IsTailCall = false;
+      }
+    } else {
+      CLI.IsTailCall = false;
+      if (MustTail)
+        fail(DL, DAG, "WebAssembly 'tail-call' feature not enabled");
+    }
   }
 
   SmallVectorImpl<ISD::InputArg> &Ins = CLI.Ins;


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D65246.211610.patch
Type: text/x-patch
Size: 2820 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20190724/d6377dee/attachment.bin>