[RS4GC] Lower calls to @llvm.experimental.deoptimize

This changes RS4GC to lower calls to ``@llvm.experimental.deoptimize``
to gc.statepoints wrapping ``__llvm_deoptimize``, and changes
``callsGCLeafFunction`` to recognize ``@llvm.experimental.deoptimize``
as a non GC leaf function.

I've had to hard code the ``"__llvm_deoptimize"`` name in
RewriteStatepointsForGC; since ``TargetLibraryInfo`` is available only
during codegen.  This isn't without precedent in the codebase, so I'm
not overtly concerned.

llvm-svn: 264456

1 files changed, 9 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 0ca5a962e6a..bd8b7c45d1a 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -1603,18 +1603,18 @@ unsigned llvm::replaceDominatedUsesWith(Value *From, Value *To,
 }
 
 bool llvm::callsGCLeafFunction(ImmutableCallSite CS) {
-  if (isa<IntrinsicInst>(CS.getInstruction()))
-    // Most LLVM intrinsics are things which can never take a safepoint.
-    // As a result, we don't need to have the stack parsable at the
-    // callsite.  This is a highly useful optimization since intrinsic
-    // calls are fairly prevalent, particularly in debug builds.
-    return true;
-
   // Check if the function is specifically marked as a gc leaf function.
   if (CS.hasFnAttr("gc-leaf-function"))
     return true;
-  if (const Function *F = CS.getCalledFunction())
-    return F->hasFnAttribute("gc-leaf-function");
+  if (const Function *F = CS.getCalledFunction()) {
+    if (F->hasFnAttribute("gc-leaf-function"))
+      return true;
+
+    if (auto IID = F->getIntrinsicID())
+      // Most LLVM intrinsics do not take safepoints.
+      return IID != Intrinsic::experimental_gc_statepoint &&
+             IID != Intrinsic::experimental_deoptimize;
+  }
 
   return false;
 }