[WinEH] Fix CatchRetSuccessorColorMap accounting

[JosephTremoulet]

Summary

We now use the block for the catchpad itself, rather than its normal
successor, as the funclet entry.
Putting the normal successor in the map leads downstream funclet
membership computations to erroneous results.

[rnk]

lgtm, thanks, I just hit this. :)

lib/CodeGen/WinEHPrepare.cpp

for (auto &Funclet : FuncletBlocks) {
     for (User *Exit : CatchPad->users()) {
       auto *CatchReturn = dyn_cast<CatchReturnInst>(Exit);
       if (!CatchReturn)
         continue;
       BasicBlock *CatchRetSuccessor = CatchReturn->getSuccessor();
       std::set<BasicBlock *> &SuccessorColors = BlockColors[CatchRetSuccessor];
       assert(SuccessorColors.size() == 1 && "Expected BB to be monochrome!");
       BasicBlock *Color = *SuccessorColors.begin();
-      if (auto *CPI = dyn_cast<CatchPadInst>(Color->getFirstNonPHI()))
-        Color = CPI->getNormalDest();
       // Record the catchret successor's funclet membership.
       FuncInfo.CatchRetSuccessorColorMap[CatchReturn] = Color;
     }
   }
 }
 
 void WinEHPrepare::demotePHIsOnFunclets(Function &F) {
   // Strip PHI nodes off of EH pads.

test/CodeGen/X86/win-catchpad-nested.ll

+; RUN: llc -mtriple=x86_64-pc-windows-coreclr < %s | FileCheck %s
+
+declare void @ProcessCLRException()
+
+declare void @f()
+
+define void @test1() personality void ()* @ProcessCLRException {
+entry:
+  invoke void @f()
+          to label %exit unwind label %outer.pad
+outer.pad:
+  %outer = catchpad [i32 1]
+          to label %outer.catch unwind label %outer.end
+outer.catch:
+  invoke void @f()
+          to label %outer.ret unwind label %inner.pad
+inner.pad:
+  %inner = catchpad [i32 2]
+          to label %inner.ret unwind label %inner.end
+inner.ret:
+  catchret %inner to label %outer.ret
+inner.end:
+  catchendpad unwind label %outer.end
+outer.ret:
+  catchret %outer to label %exit
+outer.end:
+  catchendpad unwind to caller
+exit:
+  ret void
+}
+
+; Check the catchret targets
+; CHECK-LABEL: test1: # @test1
+; CHECK: [[Exit:^[^: ]+]]: # %exit
+; CHECK: [[OuterRet:^[^: ]+]]: # %outer.ret
+; CHECK-NEXT: leaq [[Exit]](%rip), %rax
+; CHECK:      retq   # CATCHRET
+; CHECK: {{^[^: ]+}}: # %inner.pad
+; CHECK: .seh_endprolog
+; CHECK-NEXT: leaq [[OuterRet]](%rip), %rax
+; CHECK:      retq   # CATCHRET