[Statepoints] Initial support for relocating vectors of pointers

Currently, we try to split vectors of pointers back into their component pointer elements during rewrite-statepoints-for-gc. This is less than ideal since presumably the vectorizer chose to vectorize for a reason. :) It's also been a source of bugs - in particular, the relocation logic as currently implemented was recently discovered to be wrong.

The alternate approach is to allow gc.relocates of vector-of-pointer type and update the backend to handle them. That's what this patch tries to do. This won't actually enable vector-of-pointers in practice - there are some RS4GC changes needed - but the lowering is standalone and testable so it makes sense to separate.

Note that there are some known cases around vector constants which this patch does not handle. Once this is in, I'll send another patch with individual fixes and test cases. 

Differential Revision: http://reviews.llvm.org/D15632

llvm-svn: 257022

1 files changed, 14 insertions, 8 deletions

diff --git a/llvm/lib/IR/Verifier.cpp b/llvm/lib/IR/Verifier.cpp
index 6dfb05d9449..fb42ea16c99 100644
--- a/llvm/lib/IR/Verifier.cpp
+++ b/llvm/lib/IR/Verifier.cpp
@@ -3652,6 +3652,9 @@ void Verifier::visitIntrinsicCallSite(Intrinsic::ID ID, CallSite CS) {
   case Intrinsic::experimental_gc_relocate: {
     Assert(CS.getNumArgOperands() == 3, "wrong number of arguments", CS);
 
+    Assert(isa<PointerType>(CS.getType()->getScalarType()),
+           "gc.relocate must return a pointer or a vector of pointers", CS);
+
     // Check that this relocate is correctly tied to the statepoint
 
     // This is case for relocate on the unwinding path of an invoke statepoint
@@ -3734,17 +3737,20 @@ void Verifier::visitIntrinsicCallSite(Intrinsic::ID ID, CallSite CS) {
            "'gc parameters' section of the statepoint call",
            CS);
 
-    // Relocated value must be a pointer type, but gc_relocate does not need to return the
-    // same pointer type as the relocated pointer. It can be casted to the correct type later
-    // if it's desired. However, they must have the same address space.
+    // Relocated value must be either a pointer type or vector-of-pointer type,
+    // but gc_relocate does not need to return the same pointer type as the
+    // relocated pointer. It can be casted to the correct type later if it's
+    // desired. However, they must have the same address space and 'vectorness'
     GCRelocateInst &Relocate = cast<GCRelocateInst>(*CS.getInstruction());
-    Assert(Relocate.getDerivedPtr()->getType()->isPointerTy(),
+    Assert(Relocate.getDerivedPtr()->getType()->getScalarType()->isPointerTy(),
            "gc.relocate: relocated value must be a gc pointer", CS);
 
-    // gc_relocate return type must be a pointer type, and is verified earlier in
-    // VerifyIntrinsicType().
-    Assert(cast<PointerType>(CS.getType())->getAddressSpace() ==
-           cast<PointerType>(Relocate.getDerivedPtr()->getType())->getAddressSpace(),
+    auto ResultType = CS.getType();
+    auto DerivedType = Relocate.getDerivedPtr()->getType();
+    Assert(ResultType->isVectorTy() == DerivedType->isVectorTy(),
+           "gc.relocate: vector relocates to vector and pointer to pointer", CS);
+    Assert(ResultType->getPointerAddressSpace() ==
+           DerivedType->getPointerAddressSpace(),
            "gc.relocate: relocating a pointer shouldn't change its address space", CS);
     break;
   }