Merge pull request #82476 from eeckstein/fix-temp-lvalue-elimination

TempLValueElimination: fix a stupid bug when combining `copy_addr` with a following `destroy_addr`

Author: eeckstein

SwiftCompilerSources/Sources/Optimizer/FunctionPasses/TempLValueElimination.swift

@@ -216,10 +216,7 @@ private extension FullApplySite {
 ///   destroy_addr %source
 /// ```
 private func combineWithDestroy(copy: CopyAddrInst, _ context: FunctionPassContext) {
-  guard !copy.isTakeOfSource,
-        let destroy = copy.source.uses.users(ofType: DestroyAddrInst.self).first,
-        destroy.parentBlock == copy.parentBlock
-  else {
+  guard !copy.isTakeOfSource else {
     return
   }
 
@@ -228,20 +225,21 @@ private func combineWithDestroy(copy: CopyAddrInst, _ context: FunctionPassConte
   defer { debugInsts.deinitialize() }
 
   for inst in InstructionList(first: copy.next) {
-    if inst == destroy {
-      break
-    }
-    if let debugInst = inst as? DebugValueInst, debugInst.operand.value == copy.source {
-      debugInsts.append(debugInst)
-    }
-    if inst.mayReadOrWriteMemory {
+    switch inst {
+    case let destroy as DestroyAddrInst where destroy.destroyedAddress == copy.source:
+      copy.set(isTakeOfSource: true, context)
+      context.erase(instruction: destroy)
+      // Don't let debug info think that the value is still valid after the `copy [take]`.
+      context.erase(instructions: debugInsts)
       return
+    case let debugInst as DebugValueInst where debugInst.operand.value == copy.source:
+      debugInsts.append(debugInst)
+    default:
+      if inst.mayReadOrWriteMemory {
+        return
+      }
     }
   }
-  copy.set(isTakeOfSource: true, context)
-  context.erase(instruction: destroy)
-  // Don't let debug info think that the value is still valid after the `copy [take]`.
-  context.erase(instructions: debugInsts)
 }
 
 private extension Value {

test/SILOptimizer/templvalueopt_ossa.sil

@@ -630,3 +630,25 @@ bb0(%0 : @guaranteed $__ContiguousArrayStorageBase):
   return %12
 }
 
+// CHECK-LABEL: sil [ossa] @destroy_before_copy :
+// CHECK:       bb1:
+// CHECK-NEXT:    destroy_addr
+// CHECK-LABEL: } // end sil function 'destroy_before_copy'
+sil [ossa] @destroy_before_copy : $@convention(thin) (@in_guaranteed Child) -> @out Child {
+bb0(%0 : $*Child, %1 : $*Child):
+  %2 = alloc_stack $Child
+  copy_addr %1 to [init] %2
+  br bb1
+
+bb1:
+  destroy_addr %2
+  copy_addr %1 to [init] %2
+  copy_addr %2 to [init] %0
+  br bb2
+
+bb2:
+  copy_addr [take] %2 to %0
+  dealloc_stack %2
+  %r = tuple ()
+  return %r
+}