ComputeSideEffects: consider effects in dead-end blocks

It was a wrong assumption that we can ignore effects in dead-end blocks.

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/ComputeSideEffects.swift

@@ -44,16 +44,9 @@ let computeSideEffects = FunctionPass(name: "compute-side-effects", {
 
   var collectedEffects = CollectedEffects(function: function, context)
 
-  var deadEndBlocks = DeadEndBlocks(function: function, context)
-  defer { deadEndBlocks.deinitialize() }
-  
   // First step: collect effects from all instructions.
   //
   for block in function.blocks {
-    // Effects in blocks from which the function doesn't return are not relevant for the caller.
-    if deadEndBlocks.isDeadEnd(block: block) {
-      continue
-    }
     for inst in block.instructions {
       collectedEffects.addInstructionEffects(inst)
     }

test/SILOptimizer/side_effects.sil

@@ -655,7 +655,7 @@ bb0(%0 : $*X):
 }
 
 // CHECK-LABEL: sil @call_noreturn
-// CHECK-NEXT:  [global: ]
+// CHECK-NEXT:  [global: read]
 // CHECK-NEXT:  {{^[^[]}}
 sil @call_noreturn : $@convention(thin) () -> () {
 bb0: