[coroutines] Handle spills before catchswitch

If we need to spill the result of the PHI instruction, we insert the spill after
all of the PHIs and EHPads, however, in a catchswitch block there is no
room to insert the spill. Make room by splitting away catchswitch into a separate
block.

Before the fix:

    catch.dispatch:
       %val = phi i32 [ 1, %if.then ], [ 2, %if.else ]
       %switch = catchswitch within none [label %catch] unwind label %cleanuppad

After:

    catch.dispatch:
       %val = phi i32 [ 1, %if.then ], [ 2, %if.else ]
       %tok = cleanuppad within none []
       ; spill goes here
       cleanupret from %tok unwind label %catch.dispatch.switch
    catch.dispatch.switch:
       %switch = catchswitch within none [label %catch] unwind label %cleanuppad

https://reviews.llvm.org/D31846

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303232 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Coroutines/CoroFrame.cpp b/lib/Transforms/Coroutines/CoroFrame.cpp
index 4480220f2cd499157f3488168a69762e79c29807..417d57f7625b435378cae661a65425f36e55fd52 100644 (file)
--- a/lib/Transforms/Coroutines/CoroFrame.cpp
+++ b/lib/Transforms/Coroutines/CoroFrame.cpp
@@ -347,6 +347,27 @@ static StructType *buildFrameType(Function &F, coro::Shape &Shape,
   return FrameTy;
 }
 
+// We need to make room to insert a spill after initial PHIs, but before
+// catchswitch instruction. Placing it before violates the requirement that
+// catchswitch, like all other EHPads must be the first nonPHI in a block.
+//
+// Split away catchswitch into a separate block and insert in its place:
+//
+//   cleanuppad <InsertPt> cleanupret.
+//
+// cleanupret instruction will act as an insert point for the spill.
+static Instruction *splitBeforeCatchSwitch(CatchSwitchInst *CatchSwitch) {
+  BasicBlock *CurrentBlock = CatchSwitch->getParent();
+  BasicBlock *NewBlock = CurrentBlock->splitBasicBlock(CatchSwitch);
+  CurrentBlock->getTerminator()->eraseFromParent();
+
+  auto *CleanupPad =
+      CleanupPadInst::Create(CatchSwitch->getParentPad(), {}, "", CurrentBlock);
+  auto *CleanupRet =
+      CleanupReturnInst::Create(CleanupPad, NewBlock, CurrentBlock);
+  return CleanupRet;
+}
+
 // Replace all alloca and SSA values that are accessed across suspend points
 // with GetElementPointer from coroutine frame + loads and stores. Create an
 // AllocaSpillBB that will become the new entry block for the resume parts of
@@ -437,8 +458,11 @@ static Instruction *insertSpills(SpillInfo &Spills, coro::Shape &Shape) {
           InsertPt = NewBB->getTerminator();
         } else if (dyn_cast<PHINode>(CurrentValue)) {
           // Skip the PHINodes and EH pads instructions.
-          InsertPt =
-              &*cast<Instruction>(E.def())->getParent()->getFirstInsertionPt();
+          BasicBlock *DefBlock = cast<Instruction>(E.def())->getParent();
+          if (auto *CSI = dyn_cast<CatchSwitchInst>(DefBlock->getTerminator()))
+            InsertPt = splitBeforeCatchSwitch(CSI);
+          else
+            InsertPt = &*DefBlock->getFirstInsertionPt();
         } else {
           // For all other values, the spill is placed immediately after
           // the definition.

diff --git a/test/Transforms/Coroutines/coro-catchswitch.ll b/test/Transforms/Coroutines/coro-catchswitch.ll
new file mode 100644 (file)
index 0000000..dd06f12
--- /dev/null
+++ b/test/Transforms/Coroutines/coro-catchswitch.ll
@@ -0,0 +1,88 @@
+; Verifies that we can insert the spill for a PHI preceding the catchswitch
+; RUN: opt < %s -coro-split -S | FileCheck %s
+
+target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
+target triple = "i686-pc-windows-msvc"
+
+; CHECK-LABEL: define void @f(
+define void @f(i1 %cond) "coroutine.presplit"="1" personality i32 0 {
+entry:
+  %id = call token @llvm.coro.id(i32 8, i8* null, i8* null, i8* null)
+  %size = call i32 @llvm.coro.size.i32()
+  %alloc = call i8* @malloc(i32 %size)
+  %hdl = call i8* @llvm.coro.begin(token %id, i8* %alloc)
+  br i1 %cond, label %if.else, label %if.then
+
+if.then:
+  invoke void @may_throw1()
+          to label %coro.ret unwind label %catch.dispatch
+
+if.else:
+  invoke void @may_throw2()
+          to label %coro.ret unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %if.else, %if.then
+  %val = phi i32 [ 1, %if.then ], [ 2, %if.else ]
+  %switch = catchswitch within none [label %catch] unwind label %cleanuppad
+
+; Verifies that we split out the PHI into a separate block
+; added a cleanuppad spill cleanupret unwinding into the catchswitch.
+
+; CHECK: catch.dispatch:
+; CHECK:  %val = phi i32 [ 2, %if.else ], [ 1, %if.then ]
+; CHECK:  %[[Pad:.+]] = cleanuppad within none []
+; CHECK:  %val.spill.addr = getelementptr inbounds %f.Frame, %f.Frame* %FramePtr, i32 0, i32 4
+; CHECK:  store i32 %val, i32* %val.spill.addr
+; CHECK:  cleanupret from %[[Pad]] unwind label %[[Switch:.+]]
+
+; CHECK: [[Switch]]:
+; CHECK: %switch = catchswitch within none [label %catch] unwind to caller
+
+catch:                                            ; preds = %catch.dispatch
+  %pad = catchpad within %switch [i8* null, i32 64, i8* null]
+  catchret from %pad to label %suspend
+
+suspend:
+  %sp = call i8 @llvm.coro.suspend(token none, i1 false)
+  switch i8 %sp, label %coro.ret [
+    i8 0, label %resume
+    i8 1, label %coro.ret
+  ]
+
+resume:                                   ; preds = %await2.suspend
+  call void @print(i32 %val)
+  br label %coro.ret
+
+coro.ret:
+  call i1 @llvm.coro.end(i8* %hdl, i1 0)
+    ret void
+
+cleanuppad:
+  %cpad = cleanuppad within none []
+  cleanupret from %cpad unwind to caller
+}
+
+; Function Attrs: argmemonly nounwind readonly
+declare token @llvm.coro.id(i32, i8* readnone, i8* nocapture readonly, i8*) #1
+
+; Function Attrs: nounwind
+declare i1 @llvm.coro.alloc(token) #2
+
+; Function Attrs: nobuiltin
+declare i32 @llvm.coro.size.i32() #4
+declare i8* @llvm.coro.begin(token, i8* writeonly) #2
+declare token @llvm.coro.save(i8*)
+declare i8 @llvm.coro.suspend(token, i1)
+
+declare void @may_throw1()
+declare void @may_throw2()
+declare void @print(i32)
+declare noalias i8* @malloc(i32)
+declare void @free(i8*)
+
+declare i1 @llvm.coro.end(i8*, i1) #2
+
+; Function Attrs: nobuiltin nounwind
+
+; Function Attrs: argmemonly nounwind readonly
+declare i8* @llvm.coro.free(token, i8* nocapture readonly) #1