[Sink] Don't move landingpads

[loladiro]

Summary

Moving landingpads into successor basic blocks makes the verifier sad. I assume the same is true for cleanuppads. Any other EH related pads that need to be put here? Bugpoint-reduced C++ testcase is included.

[majnemer]

LGTM with tweaks

lib/Transforms/Scalar/Sink.cpp

172–173 ↗

(On Diff #39621)

This can be made more concise by writing it as isa<TerminatorInst>(Inst) || isa<PHINode(Inst) || Inst->isEHPad()

test/Transforms/Sink/landingpad.ll

4 ↗

(On Diff #39621)

Would you mind renaming these functions something like f, g, and h ?

38–39 ↗

(On Diff #39621)

These attributes are not really relevant to this test case.

llvm/trunk/lib/Transforms/Scalar/Sink.cpp

static bool isSafeToMove(Instruction *Inst, AliasAnalysis *AA,
 
   if (LoadInst *L = dyn_cast<LoadInst>(Inst)) {
     MemoryLocation Loc = MemoryLocation::get(L);
     for (Instruction *S : Stores)
       if (AA->getModRefInfo(S, Loc) & MRI_Mod)
         return false;
   }
 
-  if (isa<TerminatorInst>(Inst) || isa<PHINode>(Inst))
+  if (isa<TerminatorInst>(Inst) || isa<PHINode>(Inst) || Inst->isEHPad())
     return false;
 
   // Convergent operations cannot be made control-dependent on additional
   // values.
   if (auto CS = CallSite(Inst)) {
     if (CS.hasFnAttr(Attribute::Convergent))
       return false;
   }

llvm/trunk/test/Transforms/Sink/landingpad.ll

+; Test that we don't sink landingpads
+; RUN: opt -sink -S < %s | FileCheck %s
+
+declare hidden void @g()
+declare void @h()
+declare i32 @__gxx_personality_v0(...)
+
+define void @f() personality i8* bitcast (i32 (...)* @__gxx_personality_v0 to i8*) {
+entry:
+  invoke void @g()
+          to label %invoke.cont.15 unwind label %lpad
+
+invoke.cont.15:
+  unreachable
+
+; CHECK: lpad:
+; CHECK: %0 = landingpad { i8*, i32 }
+lpad:
+  %0 = landingpad { i8*, i32 }
+          catch i8* null
+  invoke void @h()
+          to label %invoke.cont unwind label %lpad.1
+
+; CHECK: invoke.cont
+; CHECK-NOT: %0 = landingpad { i8*, i32 }
+invoke.cont:
+  ret void
+
+lpad.1:
+  %1 = landingpad { i8*, i32 }
+          cleanup
+  resume { i8*, i32 } %1
+}