IR+AArch64: add a "swiftasync" argument attribute.

This extends any frame record created in the function to include that
parameter, passed in X22.

The new record looks like [X22, FP, LR] in memory, and FP is stored with 0b0001
in bits 63:60 (CodeGen assumes they are 0b0000 in normal operation). The effect
of this is that tools walking the stack should expect to see one of three
values there:

  * 0b0000 => a normal, non-extended record with just [FP, LR]
  * 0b0001 => the extended record [X22, FP, LR]
  * 0b1111 => kernel space, and a non-extended record.

All other values are currently reserved.

If compiling for arm64e this context pointer is address-discriminated with the
discriminator 0xc31a and the DB (process-specific) key.

There is also an "i8** @llvm.swift.async.context.addr()" intrinsic providing
front-ends access to this slot (and forcing its creation initialized to nullptr
if necessary).

1 files changed, 5 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index e9eea5b..7d6d1ea 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -9385,6 +9385,7 @@ TargetLowering::LowerCallTo(TargetLowering::CallLoweringInfo &CLI) const {
     Entry.IsByRef = false;
     Entry.IsReturned = false;
     Entry.IsSwiftSelf = false;
+    Entry.IsSwiftAsync = false;
     Entry.IsSwiftError = false;
     Entry.IsCFGuardTarget = false;
     Entry.Alignment = Alignment;
@@ -9498,6 +9499,8 @@ TargetLowering::LowerCallTo(TargetLowering::CallLoweringInfo &CLI) const {
         Flags.setSRet();
       if (Args[i].IsSwiftSelf)
         Flags.setSwiftSelf();
+      if (Args[i].IsSwiftAsync)
+        Flags.setSwiftAsync();
       if (Args[i].IsSwiftError)
         Flags.setSwiftError();
       if (Args[i].IsCFGuardTarget)
@@ -10035,6 +10038,8 @@ void SelectionDAGISel::LowerArguments(const Function &F) {
         Flags.setSRet();
       if (Arg.hasAttribute(Attribute::SwiftSelf))
         Flags.setSwiftSelf();
+      if (Arg.hasAttribute(Attribute::SwiftAsync))
+        Flags.setSwiftAsync();
       if (Arg.hasAttribute(Attribute::SwiftError))
         Flags.setSwiftError();
       if (Arg.hasAttribute(Attribute::ByVal))