commit be985b1ec701e12c9c02cd1a7933759a15b68a71
author Arnold Schwaighofer <aschwaighofer@apple.com> Sat Apr 08 20:01:14 2017 -0700
committer GitHub <noreply@github.com> Sat Apr 08 20:01:14 2017 -0700
tree 0a45b8f4fef48a5f29dc3a031b949a263dc1904e
parent 8f3d90efa7a696610306106b04c5f22b20d59fa9
parent 789a9b1d091232c9e15854e4d738fc3087d06ffe

Merge pull request #8648 from aschwaighofer/fix_dead_store_bug_value_metatype

Fix DeadStoreElim by not lying about instruction semantics

include/swift/SIL/SILNodes.def

diff --git a/include/swift/SIL/SILNodes.def b/include/swift/SIL/SILNodes.def
index 472efe0..8221f00 100644
--- a/include/swift/SIL/SILNodes.def
+++ b/include/swift/SIL/SILNodes.def
@@ -202,7 +202,7 @@
 
   // Metatypes
   INST(MetatypeInst, SILInstruction, metatype, None, DoesNotRelease)
-  INST(ValueMetatypeInst, SILInstruction, value_metatype, None, DoesNotRelease)
+  INST(ValueMetatypeInst, SILInstruction, value_metatype, MayRead, DoesNotRelease)
   INST(ExistentialMetatypeInst, SILInstruction, existential_metatype, MayRead, DoesNotRelease)
   INST(ObjCProtocolInst, SILInstruction, objc_protocol, None, DoesNotRelease)
 

test/SILOptimizer/dead_store_elim.sil

diff --git a/test/SILOptimizer/dead_store_elim.sil b/test/SILOptimizer/dead_store_elim.sil
index a0b038d..af7dcae 100644
--- a/test/SILOptimizer/dead_store_elim.sil
+++ b/test/SILOptimizer/dead_store_elim.sil
@@ -1417,3 +1417,19 @@
   dealloc_stack %1 : $*AB
   return %2 : $Builtin.Int1
 }
+
+// CHECK-LABEL: dont_remove_store
+// CHECK: load
+// CHECK: store
+// CHECK: value_metatype
+// CHECK: return
+sil @dont_remove_store : $@convention(thin) (@in_guaranteed foo) -> () {
+bb0(%0 : $*foo):
+  %1 = alloc_stack $foo
+  %2 = load %0 : $*foo
+  store %2 to %1 : $*foo
+  %3 = value_metatype $@thick foo.Type, %1 : $*foo
+  dealloc_stack %1 : $*foo
+  %20 = tuple()
+  return %20 : $()
+}