Add a command-line flag to control the Swift extended async frame info.

Introduce a new command-line flag `-swift-async-fp={auto|always|never}`
that controls how code generation sets the Swift extended async frame
info bit. There are three possibilities:

* `auto`: which determines how to set the bit based on deployment target, either
statically or dynamically via `swift_async_extendedFramePointerFlags`.
* `always`: the default, always set the bit statically, regardless of deployment
target.
* `never`: never set the bit, regardless of deployment target.

Patch by Doug Gregor <dgregor@apple.com>

Reviewed By: doug.gregor

Differential Revision: https://reviews.llvm.org/D109392

1 files changed, 14 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/CommandFlags.cpp b/llvm/lib/CodeGen/CommandFlags.cpp
index c30e1c3..8f31630 100644
--- a/llvm/lib/CodeGen/CommandFlags.cpp
+++ b/llvm/lib/CodeGen/CommandFlags.cpp
@@ -65,6 +65,7 @@ CGOPT(DenormalMode::DenormalModeKind, DenormalFP32Math)
 CGOPT(bool, EnableHonorSignDependentRoundingFPMath)
 CGOPT(FloatABI::ABIType, FloatABIForCalls)
 CGOPT(FPOpFusion::FPOpFusionMode, FuseFPOps)
+CGOPT(SwiftAsyncFramePointerMode, SwiftAsyncFramePointer)
 CGOPT(bool, DontPlaceZerosInBSS)
 CGOPT(bool, EnableGuaranteedTailCallOpt)
 CGOPT(bool, DisableTailCalls)
@@ -278,6 +279,18 @@ codegen::RegisterCodeGenFlags::RegisterCodeGenFlags() {
                      "Only fuse FP ops when the result won't be affected.")));
   CGBINDOPT(FuseFPOps);
 
+  static cl::opt<SwiftAsyncFramePointerMode> SwiftAsyncFramePointer(
+      "swift-async-fp",
+      cl::desc("Determine when the Swift async frame pointer should be set"),
+      cl::init(SwiftAsyncFramePointerMode::Always),
+      cl::values(clEnumValN(SwiftAsyncFramePointerMode::DeploymentBased, "auto",
+                            "Determine based on deployment target"),
+                 clEnumValN(SwiftAsyncFramePointerMode::Always, "always",
+                            "Always set the bit"),
+                 clEnumValN(SwiftAsyncFramePointerMode::Never, "never",
+                            "Never set the bit")));
+  CGBINDOPT(SwiftAsyncFramePointer);
+
   static cl::opt<bool> DontPlaceZerosInBSS(
       "nozero-initialized-in-bss",
       cl::desc("Don't place zero-initialized symbols into bss section"),
@@ -539,7 +552,7 @@ codegen::InitTargetOptionsFromCodeGenFlags(const Triple &TheTriple) {
   Options.ThreadModel = getThreadModel();
   Options.EABIVersion = getEABIVersion();
   Options.DebuggerTuning = getDebuggerTuningOpt();
-
+  Options.SwiftAsyncFramePointer = getSwiftAsyncFramePointer();
   return Options;
 }