[coro] Correct CurrentBlock tracking bug recently introduced

[aschwaighofer]

Summary

We use the CurrentBlock to determine whether we have already processed a
block. Don't reuse this variable for setting where we should insert the
rematerialization. The rematerialization block is different to the
current block when we rematerialize for coro suspend block users.

[aschwaighofer]

Fix clang-tidy warning - qualify auto pointer var

[nate_chandler]

lgtm

llvm/lib/Transforms/Coroutines/CoroFrame.cpp

for (const auto &E : Spills) {
     Value *Def = E.first;
     BasicBlock *CurrentBlock = nullptr;
     Instruction *CurrentMaterialization = nullptr;
     for (Instruction *U : E.second) {
       // If we have not seen this block, materialize the value.
       if (CurrentBlock != U->getParent()) {
 
         bool IsInCoroSuspendBlock = isa<AnyCoroSuspendInst>(U);
-        CurrentBlock = IsInCoroSuspendBlock
-                           ? U->getParent()->getSinglePredecessor()
-                           : U->getParent();
+        CurrentBlock = U->getParent();
+        auto *InsertBlock = IsInCoroSuspendBlock
+                                ? CurrentBlock->getSinglePredecessor()
+                                : CurrentBlock;
         CurrentMaterialization = cast<Instruction>(Def)->clone();
         CurrentMaterialization->setName(Def->getName());
         CurrentMaterialization->insertBefore(
-            IsInCoroSuspendBlock ? CurrentBlock->getTerminator()
-                                 : &*CurrentBlock->getFirstInsertionPt());
+            IsInCoroSuspendBlock ? InsertBlock->getTerminator()
+                                 : &*InsertBlock->getFirstInsertionPt());
       }
       if (auto *PN = dyn_cast<PHINode>(U)) {
         assert(PN->getNumIncomingValues() == 1 &&
                "unexpected number of incoming "
                "values in the PHINode");
         PN->replaceAllUsesWith(CurrentMaterialization);
         PN->eraseFromParent();
         continue;

llvm/test/Transforms/Coroutines/coro-async-remat.ll

+; RUN: opt < %s -enable-coroutines -O0 -S
+
+%async_func_ptr = type <{ i32, i32 }>
+%Tsq = type <{}>
+%swift.context = type { %swift.context*, void (%swift.context*)*, i64 }
+%swift.type = type { i64 }
+%FlatMapSeq = type <{}>
+%swift.error = type opaque
+%swift.opaque = type opaque
+
+@repoTU = global %async_func_ptr <{ i32 trunc (i64 sub (i64 ptrtoint (void (%Tsq*, %swift.context*, %swift.type*, %FlatMapSeq*)* @repo to i64), i64 ptrtoint (%async_func_ptr* @repoTU to i64)) to i32), i32 20 }>, section "__TEXT,__const", align 8
+
+; Function Attrs: nounwind
+declare token @llvm.coro.id.async(i32, i32, i32, i8*) #0
+
+; Function Attrs: nounwind
+declare i8* @llvm.coro.begin(token, i8* writeonly) #0
+
+; Function Attrs: nounwind
+declare i8* @llvm.coro.async.resume() #0
+
+define hidden i8* @__swift_async_resume_project_context(i8* %0) {
+entry:
+  ret i8* undef
+}
+
+define swifttailcc void @repo(%Tsq* %0, %swift.context* %1, %swift.type* %arg, %FlatMapSeq* %2) #1 {
+entry:
+  %swifterror = alloca swifterror %swift.error*, align 8
+  %3 = call token @llvm.coro.id.async(i32 20, i32 16, i32 1, i8* bitcast (%async_func_ptr* @repoTU to i8*))
+  %4 = call i8* @llvm.coro.begin(token %3, i8* null)
+  %5 = bitcast i8* undef to %swift.opaque*
+  br label %6
+
+6:                                                ; preds = %21, %15, %entry
+  br i1 undef, label %7, label %23
+
+7:                                                ; preds = %6
+  br i1 undef, label %8, label %16
+
+8:                                                ; preds = %7
+  %initializeWithTake35 = bitcast i8* undef to %swift.opaque* (%swift.opaque*, %swift.opaque*, %swift.type*)*
+  %9 = call %swift.opaque* %initializeWithTake35(%swift.opaque* noalias %5, %swift.opaque* noalias undef, %swift.type* undef) #0
+  %10 = call i8* @llvm.coro.async.resume()
+  %11 = bitcast i8* %10 to void (%swift.context*)*
+  %12 = call { i8*, %swift.error* } (i32, i8*, i8*, ...) @llvm.coro.suspend.async.sl_p0i8p0s_swift.error.4.220.413.429.445.461.672.683ss(i32 256, i8* %10, i8* bitcast (i8* (i8*)* @__swift_async_resume_project_context to i8*), i8* bitcast (void (i8*, %Tsq*, %swift.context*, %swift.opaque*, %swift.type*, i8**)* @__swift_suspend_dispatch_5.23 to i8*), i8* undef, %Tsq* undef, %swift.context* undef, %swift.opaque* %5, %swift.type* undef, i8** undef)
+  br i1 undef, label %25, label %13
+
+13:                                               ; preds = %8
+  br i1 undef, label %14, label %15
+
+14:                                               ; preds = %13
+  br label %24
+
+15:                                               ; preds = %13
+  br label %6
+
+16:                                               ; preds = %7
+  br i1 undef, label %26, label %17
+
+17:                                               ; preds = %16
+  br i1 undef, label %18, label %22
+
+18:                                               ; preds = %17
+  br i1 undef, label %27, label %19
+
+19:                                               ; preds = %18
+  br i1 undef, label %20, label %21
+
+20:                                               ; preds = %19
+  br label %24
+
+21:                                               ; preds = %19
+  br label %6
+
+22:                                               ; preds = %17
+  br label %24
+
+23:                                               ; preds = %6
+  br label %24
+
+24:                                               ; preds = %23, %22, %20, %14
+  unreachable
+
+25:                                               ; preds = %8
+  br label %28
+
+26:                                               ; preds = %16
+  br label %28
+
+27:                                               ; preds = %18
+  br label %28
+
+28:                                               ; preds = %27, %26, %25
+  unreachable
+}
+
+define dso_local swifttailcc void @__swift_suspend_dispatch_2.18() {
+entry:
+  ret void
+}
+
+define dso_local swifttailcc void @__swift_suspend_dispatch_5.19() {
+entry:
+  ret void
+}
+
+define dso_local swifttailcc void @__swift_suspend_dispatch_2.20() {
+entry:
+  ret void
+}
+
+define dso_local swifttailcc void @__swift_suspend_dispatch_4.21() {
+entry:
+  ret void
+}
+
+define dso_local swifttailcc void @__swift_suspend_dispatch_5.22() {
+entry:
+  ret void
+}
+
+define dso_local swifttailcc void @__swift_suspend_dispatch_5.23(i8* %0, %Tsq* %1, %swift.context* %2, %swift.opaque* %3, %swift.type* %4, i8** %5) {
+entry:
+  ret void
+}
+
+; Function Attrs: nounwind
+declare { i8*, %swift.error* } @llvm.coro.suspend.async.sl_p0i8p0s_swift.error.4.220.413.429.445.461.672.683ss(i32, i8*, i8*, ...) #0
+
+attributes #0 = { nounwind }
+attributes #1 = { "tune-cpu"="generic" }
+
+!llvm.linker.options = !{!0}
+
+!0 = !{!"-lobjc"}