Merge pull request #60902 from eeckstein/fix-temp-rvalue-opt

TempRValueOpt: fix a wrong assert.

Author: eeckstein

lib/SILOptimizer/Transforms/TempRValueElimination.cpp

@@ -400,10 +400,15 @@ bool TempRValueOptPass::extendAccessScopes(
       if (endAccessToMove)
         return false;
       // Is this the end of an access scope of the copy-source?
-      if (!aa->isNoAlias(copySrc, endAccess->getSource())) {
-        assert(endAccess->getBeginAccess()->getAccessKind() ==
-                 SILAccessKind::Read &&
-               "a may-write end_access should not be in the copysrc lifetime");
+      if (!aa->isNoAlias(copySrc, endAccess->getSource()) &&
+
+          // There cannot be any aliasing modifying accesses within the liferange
+          // of the temporary, because we would have cought this in
+          // `getLastUseWhileSourceIsNotModified`.
+          // But there are cases where `AliasAnalysis::isNoAlias` is less precise
+          // than `AliasAnalysis::mayWriteToMemory`. Therefore, just ignore any
+          // non-read accesses.
+          endAccess->getBeginAccess()->getAccessKind() == SILAccessKind::Read) {
 
         // Don't move instructions beyond the block's terminator.
         if (isa<TermInst>(lastUseInst))

test/SILOptimizer/temp_rvalue_opt.sil

@@ -739,3 +739,23 @@ bb0(%0 : $*Klass):
   %9999 = tuple()
   return %9999 : $()
 }
+
+// CHECK-LABEL: sil @test_aliasing_modify_access
+// CHECK:         [[A:%.*]] = ref_element_addr [immutable] %0 : $Klass, #Klass.a
+// CHECK-NOT:     copy_addr
+// CHECK:         [[L:%.*]] = load [[A]]
+// CHECK:         return [[L]]
+// CHECK:       } // end sil function 'test_aliasing_modify_access'
+sil @test_aliasing_modify_access : $@convention(thin) (@guaranteed Klass, @guaranteed Klass) -> @owned String {
+bb0(%0 : $Klass, %1 : $Klass):
+  %2 = ref_element_addr [immutable] %0 : $Klass, #Klass.a
+  %3 = alloc_stack $String
+  copy_addr %2 to [initialization] %3 : $*String
+  %4 = ref_element_addr %1 : $Klass, #Klass.a
+  %5 = begin_access [modify] [dynamic] [no_nested_conflict] %4 : $*String
+  end_access %5 : $*String
+  %323 = load %3 : $*String
+  destroy_addr %3 : $*String
+  dealloc_stack %3 : $*String
+  return %323 : $String
+}