1 files changed, 19 insertions, 15 deletions
diff --git a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
index 64e75548e0f..877e55928d4 100644
--- a/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
+++ b/llvm/lib/Transforms/Utils/SimplifyCFG.cpp
@@ -1428,6 +1428,25 @@ static bool canSinkInstructions(
     if (I0->getOperand(OI)->getType()->isTokenTy())
       // Don't touch any operand of token type.
       return false;
+
+    // Because SROA can't handle speculating stores of selects, try not
+    // to sink loads or stores of allocas when we'd have to create a PHI for
+    // the address operand. Also, because it is likely that loads or stores
+    // of allocas will disappear when Mem2Reg/SROA is run, don't sink them.
+    // This can cause code churn which can have unintended consequences down
+    // the line - see https://llvm.org/bugs/show_bug.cgi?id=30244.
+    // FIXME: This is a workaround for a deficiency in SROA - see
+    // https://llvm.org/bugs/show_bug.cgi?id=30188
+    if (OI == 1 && isa<StoreInst>(I0) &&
+        any_of(Insts, [](const Instruction *I) {
+          return isa<AllocaInst>(I->getOperand(1));
+        }))
+      return false;
+    if (OI == 0 && isa<LoadInst>(I0) && any_of(Insts, [](const Instruction *I) {
+          return isa<AllocaInst>(I->getOperand(0));
+        }))
+      return false;
+
     auto SameAsI0 = [&I0, OI](const Instruction *I) {
       assert(I->getNumOperands() == I0->getNumOperands());
       return I->getOperand(OI) == I0->getOperand(OI);
@@ -1441,21 +1460,6 @@ static bool canSinkInstructions(
         // FIXME: if the call was *already* indirect, we should do this.
         return false;
       }
-      // Because SROA can't handle speculating stores of selects, try not
-      // to sink loads or stores of allocas when we'd have to create a PHI for
-      // the address operand.
-      // FIXME: This is a workaround for a deficiency in SROA - see
-      // https://llvm.org/bugs/show_bug.cgi?id=30188
-      if (OI == 1 && isa<StoreInst>(I0) &&
-          any_of(Insts, [](const Instruction *I) {
-            return isa<AllocaInst>(I->getOperand(1));
-          }))
-        return false;
-      if (OI == 0 && isa<LoadInst>(I0) &&
-          any_of(Insts, [](const Instruction *I) {
-            return isa<AllocaInst>(I->getOperand(0));
-          }))
-        return false;
       for (auto *I : Insts)
         PHIOperands[I].push_back(I->getOperand(OI));
     }