ComputeSideEffects: correct side effects for destroy_addr

A destroy_addr also involves a read from the address. It's equivalent to a `%x = load [take]` and `destroy_value %x`.
It's also a write, because the stored value is not available anymore after the destroy.

Fixes a compiler crash in SILMem2Reg.

rdar://103879105

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ComputeSideEffects.swift

@@ -98,6 +98,11 @@ private struct CollectedEffects {
       addDestroyEffects(of: inst.operands[0].value)
 
     case let da as DestroyAddrInst:
+      // A destroy_addr also involves a read from the address. It's equivalent to a `%x = load [take]` and `destroy_value %x`.
+      addEffects(.read, to: da.operand)
+      // Conceptually, it's also a write, because the stored value is not available anymore after the destroy
+      addEffects(.write, to: da.operand)
+
       addDestroyEffects(of: da.operand)
 
     case let copy as CopyAddrInst:
@@ -108,12 +113,16 @@ private struct CollectedEffects {
         addEffects(.copy, to: copy.source)
       }
       if !copy.isInitializationOfDest {
+        // Like for destroy_addr, the destroy also involves a read.
+        addEffects(.read, to: copy.destination)
         addDestroyEffects(of: copy.destination)
       }
 
     case let store as StoreInst:
       addEffects(.write, to: store.destination)
       if store.destinationOwnership == .assign {
+        // Like for destroy_addr, the destroy also involves a read.
+        addEffects(.read, to: store.destination)
         addDestroyEffects(of: store.destination)
       }
 

test/SILOptimizer/side_effects.sil

@@ -436,7 +436,7 @@ bb0(%0 : @owned $SP):
 }
 
 // CHECK-LABEL: sil [ossa] @store_destoys
-// CHECK-NEXT:  [%0: write v**, destroy v**]
+// CHECK-NEXT:  [%0: read v**, write v**, destroy v**]
 // CHECK-NEXT:  [%1: write c*.v**, copy c*.v**]
 // CHECK-NEXT:  [global: write,copy]
 // CHECK-NEXT:  {{^[^[]}}
@@ -448,7 +448,7 @@ bb0(%0 : $*X, %1 : @owned $X):
 }
 
 // CHECK-LABEL: sil [ossa] @unknown_destructor_effects
-// CHECK-NEXT:  [%0: write v**, destroy v**]
+// CHECK-NEXT:  [%0: read v**, write v**, destroy v**]
 // CHECK-NEXT:  [%1: read c*.v**, write c*.v**, copy c*.v**, destroy c*.v**]
 // CHECK-NEXT:  [global: read,write,copy,destroy,allocate,deinit_barrier]
 // CHECK-NEXT:  {{^[^[]}}
@@ -471,7 +471,7 @@ bb0(%0 : $*X, %1 : @owned $X):
 }
 
 // CHECK-LABEL: sil [ossa] @copy_destoys
-// CHECK-NEXT:  [%0: write v**, destroy v**]
+// CHECK-NEXT:  [%0: read v**, write v**, destroy v**]
 // CHECK-NEXT:  [%1: read v**, copy v**]
 // CHECK-NEXT:  [global: write,copy]
 // CHECK-NEXT:  {{^[^[]}}
@@ -518,7 +518,7 @@ bb0(%0 : @owned $SP):
 }
 
 // CHECK-LABEL: sil [ossa] @destroy_addr_effects
-// CHECK-NEXT:  [%0: destroy v**]
+// CHECK-NEXT:  [%0: read v**, write v**, destroy v**]
 // CHECK-NEXT:  [global: write,copy]
 // CHECK-NEXT:  {{^[^[]}}
 sil [ossa] @destroy_addr_effects : $@convention(thin) (@in X) -> () {