Merge pull request #15454 from aschwaighofer/irgen_fix_mem_attr_witness_table_accessor_conditional_conformance_4.1

[4.1] IRGen: Fix witness-table accessors for conditional conformances

Author: aschwaighofer

lib/IRGen/GenProto.cpp

@@ -1064,6 +1064,7 @@ static llvm::Value *emitWitnessTableAccessorCall(
   // If the conformance is generic, the accessor takes the metatype plus
   // possible conditional conformances arguments.
   llvm::CallInst *call;
+  bool requiresMemoryArguments = false;
   if (conformance->witnessTableAccessorRequiresArguments()) {
     // Emit the source metadata if we haven't yet.
     if (!*srcMetadataCache) {
@@ -1076,13 +1077,14 @@ static llvm::Value *emitWitnessTableAccessorCall(
 
     call = IGF.Builder.CreateCall(
         accessor, {*srcMetadataCache, conditionalTables, numConditionalTables});
-
+    requiresMemoryArguments = true;
   } else {
     call = IGF.Builder.CreateCall(accessor, {});
   }
 
   call->setCallingConv(IGF.IGM.DefaultCC);
-  call->setDoesNotAccessMemory();
+  if (!requiresMemoryArguments)
+    call->setDoesNotAccessMemory();
   call->setDoesNotThrow();
 
   return call;

test/Inputs/conditional_conformance_basic_conformances.swift

@@ -102,7 +102,7 @@ public func single_concrete() {
 // CHECK-NEXT:    [[A_P2_PTR:%.*]] = getelementptr inbounds i8**, i8*** [[CONDITIONAL_REQUIREMENTS]], i32 0
 // CHECK-NEXT:    store i8** getelementptr inbounds ([0 x i8*], [0 x i8*]* @_T042conditional_conformance_basic_conformances4IsP2VAA0F0AAWP, i32 0, i32 0), i8*** [[A_P2_PTR]], align 8
 
-// CHECK-NEXT:    [[Single_P1:%.*]] = call i8** @_T042conditional_conformance_basic_conformances6SingleVyxGAA2P1A2A2P2RzlWa(%swift.type* [[Single_TYPE]], i8*** [[CONDITIONAL_REQUIREMENTS]], i64 1)
+// CHECK-NEXT:    [[Single_P1:%.*]] = call i8** @_T042conditional_conformance_basic_conformances6SingleVyxGAA2P1A2A2P2RzlWa(%swift.type* [[Single_TYPE]], i8*** [[CONDITIONAL_REQUIREMENTS]], i64 1) [[ATTRS:#[0-9]+]]
 // CHECK-NEXT:    store atomic i8** [[Single_P1]], i8*** @_T042conditional_conformance_basic_conformances6SingleVyAA4IsP2VGACyxGAA2P1A2A0G0RzlWL release, align 8
 // CHECK-NEXT:    br label %cont
 
@@ -323,3 +323,5 @@ public func double_concrete_concrete() {
 func dynamicCastToP1(_ value: Any) -> P1? {
   return value as? P1
 }
+
+// CHECK: attributes [[ATTRS]] = { nounwind }