IRGen: Fix issues when partial applying methods on resilient value types

Fixes <rdar://problem/28673540>.

Author: slavapestov

lib/IRGen/GenFunc.cpp

@@ -925,7 +925,7 @@ static llvm::Function *emitPartialApplicationForwarder(IRGenModule &IGM,
 
   // If there's a data pointer required, grab it and load out the
   // extra, previously-curried parameters.
-  } else if (!layout->isKnownEmpty()) {
+  } else {
     unsigned origParamI = outType->getParameters().size();
     assert(layout->getElements().size() == conventions.size()
            && "conventions don't match context layout");
@@ -1017,7 +1017,7 @@ static llvm::Function *emitPartialApplicationForwarder(IRGenModule &IGM,
     // If the parameters can live independent of the context, release it now
     // so we can tail call. The safety of this assumes that neither this release
     // nor any of the loads can throw.
-    if (consumesContext && !dependsOnContextLifetime)
+    if (consumesContext && !dependsOnContextLifetime && rawData)
       subIGF.emitNativeStrongRelease(rawData);
   }
 
@@ -1357,7 +1357,7 @@ void irgen::emitFunctionPartialApplication(IRGenFunction &IGF,
                                                        layout);
 
   llvm::Value *data;
-  if (layout.isKnownEmpty()) {
+  if (args.empty() && layout.isKnownEmpty()) {
     data = IGF.IGM.RefCountedNull;
   } else {
     // Allocate a new object.

lib/IRGen/GenHeap.cpp

@@ -102,6 +102,13 @@ HeapNonFixedOffsets::HeapNonFixedOffsets(IRGenFunction &IGF,
       case ElementLayout::Kind::NonFixed:
         // Start calculating non-fixed offsets from the end of the first fixed
         // field.
+        if (i == 0) {
+          totalAlign = elt.getType().getAlignmentMask(IGF, eltTy);
+          offset = totalAlign;
+          Offsets.push_back(totalAlign);
+          break;
+        }
+
         assert(i > 0 && "shouldn't begin with a non-fixed field");
         auto &prevElt = layout.getElement(i-1);
         auto prevType = layout.getElementTypes()[i-1];

test/IRGen/struct_resilience.swift

@@ -140,6 +140,26 @@ public struct StructWithIndirectResilientEnum {
 // CHECK-NEXT: ret [[INT]] [[FIELD_PAYLOAD]]
 
 
+// Partial application of methods on resilient value types
+
+public struct ResilientStructWithMethod {
+  public func method() {}
+}
+
+// Corner case -- type is address-only in SIL, but empty in IRGen
+
+// CHECK-LABEL: define{{( protected)?}} void @_TF17struct_resilience29partialApplyOfResilientMethodFT1rVS_25ResilientStructWithMethod_T_(%V17struct_resilience25ResilientStructWithMethod* noalias nocapture)
+public func partialApplyOfResilientMethod(r: ResilientStructWithMethod) {
+  _ = r.method
+}
+
+// Type is address-only in SIL, and resilient in IRGen
+
+// CHECK-LABEL: define{{( protected)?}} void @_TF17struct_resilience29partialApplyOfResilientMethodFT1sV16resilient_struct4Size_T_(%swift.opaque* noalias nocapture)
+public func partialApplyOfResilientMethod(s: Size) {
+  _ = s.method
+}
+
 // Public metadata accessor for our resilient struct
 
 // CHECK-LABEL: define{{( protected)?}} %swift.type* @_TMaV17struct_resilience6MySize()