[region-isolation] Add support for fix_lifetime.

fix_lifetime just acts as a require.

Author: gottesmm

lib/SILOptimizer/Mandatory/TransferNonSendable.cpp

@@ -2370,8 +2370,9 @@ CONSTANT_TRANSLATION(StoreInst, Store)
 CONSTANT_TRANSLATION(StoreBorrowInst, Store)
 CONSTANT_TRANSLATION(StoreWeakInst, Store)
 
-// These instructions are ignored because they cannot affect the partition
-// state - they do not manipulate what region non-sendable values lie in
+// These instructions are ignored because they cannot affect the region that a
+// value is within or because even though they are technically a use we would
+// rather emit an error on a better instruction.
 CONSTANT_TRANSLATION(AllocGlobalInst, Ignored)
 CONSTANT_TRANSLATION(DeallocBoxInst, Ignored)
 CONSTANT_TRANSLATION(DeallocStackInst, Ignored)
@@ -2389,6 +2390,9 @@ CONSTANT_TRANSLATION(MetatypeInst, Ignored)
 CONSTANT_TRANSLATION(EndApplyInst, Ignored)
 CONSTANT_TRANSLATION(AbortApplyInst, Ignored)
 
+// Instructions that only require that the region of the value be live:
+CONSTANT_TRANSLATION(FixLifetimeInst, Require)
+
 // Ignored terminators.
 CONSTANT_TRANSLATION(CondFailInst, Ignored)
 // Switch value inst is ignored since we only switch over integers and
@@ -2469,7 +2473,6 @@ CONSTANT_TRANSLATION(UnmanagedRetainValueInst, Unhandled)
 CONSTANT_TRANSLATION(UnmanagedReleaseValueInst, Unhandled)
 CONSTANT_TRANSLATION(UnmanagedAutoreleaseValueInst, Unhandled)
 CONSTANT_TRANSLATION(AutoreleaseValueInst, Unhandled)
-CONSTANT_TRANSLATION(FixLifetimeInst, Unhandled)
 CONSTANT_TRANSLATION(BeginUnpairedAccessInst, Unhandled)
 CONSTANT_TRANSLATION(EndUnpairedAccessInst, Unhandled)
 CONSTANT_TRANSLATION(AssignInst, Unhandled)

test/Concurrency/transfernonsendable_instruction_matching.sil

@@ -317,3 +317,16 @@ bb0(%0 : @owned $@callee_guaranteed @substituted <τ_0_0> () -> @out τ_0_0 for
   return %9999 : $()
 }
 
+sil [ossa] @fix_lifetime_test : $@convention(thin) @async () -> () {
+bb0:
+  %0 = function_ref @constructKlass : $@convention(thin) () -> @owned NonSendableKlass
+  %1 = apply %0() : $@convention(thin) () -> @owned NonSendableKlass
+  %2 = function_ref @transferKlass : $@convention(thin) @async (@guaranteed NonSendableKlass) -> ()
+  apply [caller_isolation=nonisolated] [callee_isolation=global_actor] %2(%1) : $@convention(thin) @async (@guaranteed NonSendableKlass) -> ()
+  // expected-warning @-1 {{passing argument of non-sendable type 'NonSendableKlass' from nonisolated context to global actor '<null>'-isolated context at this call site could yield a race with accesses later in this function}}
+  fix_lifetime %1 : $NonSendableKlass
+  // expected-note @-1 {{access here could race}}
+  destroy_value %1 : $NonSendableKlass
+  %9999 = tuple ()
+  return %9999 : $()
+}