[AArch64] Remove a use-after-free when collecting stats.

The call to mergePairedInsns() deletes MI, so the later use by isUnscaledLdSt()
is referencing freed memory.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@246033 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp b/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
index b67d2e2acf9c0122bfd2bcebcfc21eaf80abb517..f7f3bfa75957330c98911d3e3bfa63c38496cade 100644 (file)
--- a/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
+++ b/lib/Target/AArch64/AArch64LoadStoreOptimizer.cpp
@@ -984,15 +984,15 @@ bool AArch64LoadStoreOpt::optimizeBlock(MachineBasicBlock &MBB) {
       MachineBasicBlock::iterator Paired =
           findMatchingInsn(MBBI, Flags, ScanLimit);
       if (Paired != E) {
       MachineBasicBlock::iterator Paired =
           findMatchingInsn(MBBI, Flags, ScanLimit);
       if (Paired != E) {

+        ++NumPairCreated;
+        if (isUnscaledLdSt(MI))
+          ++NumUnscaledPairCreated;
+

         // Merge the loads into a pair. Keeping the iterator straight is a
         // pain, so we let the merge routine tell us what the next instruction
         // is after it's done mucking about.
         MBBI = mergePairedInsns(MBBI, Paired, Flags);
         // Merge the loads into a pair. Keeping the iterator straight is a
         // pain, so we let the merge routine tell us what the next instruction
         // is after it's done mucking about.
         MBBI = mergePairedInsns(MBBI, Paired, Flags);

-

         Modified = true;
         Modified = true;

-        ++NumPairCreated;
-        if (isUnscaledLdSt(MI))
-          ++NumUnscaledPairCreated;

         break;
       }
       ++MBBI;
         break;
       }
       ++MBBI;