Merge pull request #67634 from nate-chandler/rdar113121424

[Mem2Reg] Don't canonicalize undef.

Author: nate-chandler

lib/SILOptimizer/Transforms/SILMem2Reg.cpp

@@ -2153,6 +2153,8 @@ void MemoryToRegisters::removeSingleBlockAllocation(AllocStackInst *asi) {
 void MemoryToRegisters::collectStoredValues(AllocStackInst *asi,
                                             StackList<SILValue> &owned,
                                             StackList<SILValue> &guaranteed) {
+  if (!f.hasOwnership())
+    return;
   for (auto *use : asi->getUses()) {
     auto *user = use->getUser();
     if (auto *si = dyn_cast<StoreInst>(user)) {
@@ -2166,6 +2168,8 @@ void MemoryToRegisters::collectStoredValues(AllocStackInst *asi,
 void MemoryToRegisters::canonicalizeValueLifetimes(
     StackList<SILValue> &owned, StackList<SILValue> &guaranteed,
     BasicBlockSetVector &livePhiBlocks) {
+  if (!f.hasOwnership())
+    return;
   if (Mem2RegDisableLifetimeCanonicalization)
     return;
 
@@ -2191,6 +2195,8 @@ void MemoryToRegisters::canonicalizeValueLifetimes(
       /*pruneDebug=*/true, /*maximizeLifetime=*/!f.shouldOptimize(), &f,
       accessBlockAnalysis, domInfo, calleeAnalysis, deleter);
   for (auto value : owned) {
+    if (isa<SILUndef>(value))
+      continue;
     auto root = CanonicalizeOSSALifetime::getCanonicalCopiedDef(value);
     if (auto *copy = dyn_cast<CopyValueInst>(root)) {
       if (SILValue borrowDef = CanonicalizeBorrowScope::getCanonicalBorrowedDef(
@@ -2203,6 +2209,8 @@ void MemoryToRegisters::canonicalizeValueLifetimes(
   }
   CanonicalizeBorrowScope borrowCanonicalizer(&f, deleter);
   for (auto value : guaranteed) {
+    if (isa<SILUndef>(value))
+      continue;
     auto borrowee = CanonicalizeBorrowScope::getCanonicalBorrowedDef(value);
     if (!borrowee)
       continue;

test/SILOptimizer/mem2reg.sil

@@ -518,3 +518,16 @@ sil @load_from_uninitialized_empty : $@convention(thin) () -> (Pair<Pair<EmptySt
   dealloc_stack %addr : $*(Pair<Pair<EmptyStruct, EmptyStruct>, EmptyStruct>, (EmptyStruct, EmptyStruct), EmptyStruct)
   return %value : $(Pair<Pair<EmptyStruct, EmptyStruct>, EmptyStruct>, (EmptyStruct, EmptyStruct), EmptyStruct)
 }
+
+
+// CHECK-LABEL: sil @dont_canonicalize_undef : {{.*}} {
+// CHECK:         [[RETVAL:%[^,]+]] = tuple
+// CHECK:         return [[RETVAL]]
+// CHECK-LABEL: } // end sil function 'dont_canonicalize_undef'
+sil @dont_canonicalize_undef : $@convention(thin) () -> () {
+  %addr = alloc_stack $()
+  store undef to %addr : $*()
+  dealloc_stack %addr : $*()
+  %retval = tuple ()
+  return %retval : $()
+}

test/SILOptimizer/mem2reg_ossa.sil

@@ -730,3 +730,15 @@ exit:
   %retval = tuple ()
   return %retval : $()
 }
+
+// CHECK-LABEL: sil [ossa] @dont_canonicalize_undef : {{.*}} {
+// CHECK:         [[RETVAL:%[^,]+]] = tuple
+// CHECK:         return [[RETVAL]]
+// CHECK-LABEL: } // end sil function 'dont_canonicalize_undef'
+sil [ossa] @dont_canonicalize_undef : $@convention(thin) () -> () {
+  %addr = alloc_stack $()
+  store undef to [trivial] %addr : $*()
+  dealloc_stack %addr : $*()
+  %retval = tuple ()
+  return %retval : $()
+}