Merge pull request #66065 from gottesmm/pr-415aafa0f5636321e5435cb5f9c8bb95a8138613

[move-only] Fix a thinko in FieldSensitivePrunedLiveBlocks::updateForUse

Author: gottesmm

lib/SIL/Utils/FieldSensitivePrunedLiveness.cpp

@@ -507,19 +507,19 @@ void FieldSensitivePrunedLiveBlocks::updateForUse(
 
   auto *bb = user->getParent();
   getBlockLiveness(bb, startBitNo, endBitNo, resultingLivenessInfo);
+  assert(resultingLivenessInfo.size() == (endBitNo - startBitNo));
 
-  for (auto pair : llvm::enumerate(resultingLivenessInfo)) {
-    unsigned index = pair.index();
+  for (unsigned index : indices(resultingLivenessInfo)) {
     unsigned specificBitNo = startBitNo + index;
-    switch (pair.value()) {
+    switch (resultingLivenessInfo[index]) {
     case LiveOut:
     case LiveWithin:
       continue;
     case Dead: {
       // This use block has not yet been marked live. Mark it and its
       // predecessor blocks live.
       computeScalarUseBlockLiveness(bb, specificBitNo);
-      resultingLivenessInfo.push_back(getBlockLiveness(bb, specificBitNo));
+      resultingLivenessInfo[index] = getBlockLiveness(bb, specificBitNo);
       continue;
     }
     }
@@ -537,6 +537,7 @@ FieldSensitivePrunedLiveBlocks::getStringRef(IsLive isLive) const {
   case LiveOut:
     return "LiveOut";
   }
+  llvm_unreachable("Covered switch?!");
 }
 
 void FieldSensitivePrunedLiveBlocks::print(llvm::raw_ostream &OS) const {

test/SILOptimizer/moveonly_largetype_nocrash.swift

@@ -0,0 +1,163 @@
+// RUN: %target-swift-emit-sil -sil-verify-all -verify %s
+
+// Previously there was a latent albeit harmless bug in
+// FieldSensitivePrunedLiveness around an array inside of it re-allocating. This
+// test exercises that behavior by creating a type that is so large that it
+// cannot be stored within anything but a very large small vector (> 128
+// elements).
+
+public struct Large : ~Copyable {
+    var a0 = 0
+    var a1 = 0
+    var a2 = 0
+    var a3 = 0
+    var a4 = 0
+    var a5 = 0
+    var a6 = 0
+    var a7 = 0
+    var a8 = 0
+    var a9 = 0
+    var a10 = 0
+    var a11 = 0
+    var a12 = 0
+    var a13 = 0
+    var a14 = 0
+    var a15 = 0
+    var a16 = 0
+    var a17 = 0
+    var a18 = 0
+    var a19 = 0
+    var a20 = 0
+    var a21 = 0
+    var a22 = 0
+    var a23 = 0
+    var a24 = 0
+    var a25 = 0
+    var a26 = 0
+    var a27 = 0
+    var a28 = 0
+    var a29 = 0
+    var a30 = 0
+    var a31 = 0
+    var a32 = 0
+    var a33 = 0
+    var a34 = 0
+    var a35 = 0
+    var a36 = 0
+    var a37 = 0
+    var a38 = 0
+    var a39 = 0
+    var a40 = 0
+    var a41 = 0
+    var a42 = 0
+    var a43 = 0
+    var a44 = 0
+    var a45 = 0
+    var a46 = 0
+    var a47 = 0
+    var a48 = 0
+    var a49 = 0
+    var a50 = 0
+    var a51 = 0
+    var a52 = 0
+    var a53 = 0
+    var a54 = 0
+    var a55 = 0
+    var a56 = 0
+    var a57 = 0
+    var a58 = 0
+    var a59 = 0
+    var a60 = 0
+    var a61 = 0
+    var a62 = 0
+    var a63 = 0
+    var a64 = 0
+    var a65 = 0
+    var a66 = 0
+    var a67 = 0
+    var a68 = 0
+    var a69 = 0
+    var a70 = 0
+    var a71 = 0
+    var a72 = 0
+    var a73 = 0
+    var a74 = 0
+    var a75 = 0
+    var a76 = 0
+    var a77 = 0
+    var a78 = 0
+    var a79 = 0
+    var a80 = 0
+    var a81 = 0
+    var a82 = 0
+    var a83 = 0
+    var a84 = 0
+    var a85 = 0
+    var a86 = 0
+    var a87 = 0
+    var a88 = 0
+    var a89 = 0
+    var a90 = 0
+    var a91 = 0
+    var a92 = 0
+    var a93 = 0
+    var a94 = 0
+    var a95 = 0
+    var a96 = 0
+    var a97 = 0
+    var a98 = 0
+    var a99 = 0
+    var a100 = 0
+    var a101 = 0
+    var a102 = 0
+    var a103 = 0
+    var a104 = 0
+    var a105 = 0
+    var a106 = 0
+    var a107 = 0
+    var a108 = 0
+    var a109 = 0
+    var a110 = 0
+    var a111 = 0
+    var a112 = 0
+    var a113 = 0
+    var a114 = 0
+    var a115 = 0
+    var a116 = 0
+    var a117 = 0
+    var a118 = 0
+    var a119 = 0
+    var a120 = 0
+    var a121 = 0
+    var a122 = 0
+    var a123 = 0
+    var a124 = 0
+    var a125 = 0
+    var a126 = 0
+    var a127 = 0
+    var a128 = 0
+    var a129 = 0
+    var a130 = 0
+}
+
+func borrowVal(_ x: borrowing Large) {}
+
+var bool: Bool { false }
+
+func test() {
+    let a = Large()
+
+    if bool {
+
+    } else {
+
+    }
+
+    if bool {
+
+    } else {
+
+    }
+
+    borrowVal(a)
+}