[llvm] [AArch64] Verify ldp/stp alignment stricter (PR #83948)

[Yuta Mukai via llvm-commits]

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@@ -2349,31 +2348,38 @@ bool AArch64LoadStoreOpt::tryToPairLdStInst(MachineBasicBlock::iterator &MBBI) {
     MachineMemOperand *MemOp =
         MI.memoperands_empty() ? nullptr : MI.memoperands().front();
 
-    // Get the needed alignments to check them if
-    // ldp-aligned-only/stp-aligned-only features are opted.
-    uint64_t MemAlignment = MemOp ? MemOp->getAlign().value() : -1;
-    uint64_t TypeAlignment = MemOp ? Align(MemOp->getSize()).value() : -1;
+    // If a load/store arrives and ldp/stp-aligned-only feature is opted, check
+    // that the alignment of the source pointer is at least double the alignment
+    // of the type.
+    if ((MI.mayLoad() && Subtarget->hasLdpAlignedOnly()) ||
+        (MI.mayStore() && Subtarget->hasStpAlignedOnly())) {
+      // If there is no size/align information, cancel the transformation.
+      if (!MemOp || !MemOp->getMemoryType().isValid()) {
+        NumFailedAlignmentCheck++;
+        return false;
+      }
 
-    // If a load arrives and ldp-aligned-only feature is opted, check that the
-    // alignment of the source pointer is at least double the alignment of the
-    // type.
-    if (MI.mayLoad() && Subtarget->hasLdpAlignedOnly() && MemOp &&
-        MemAlignment < 2 * TypeAlignment)
-      return false;
+      // Get the needed alignments to check them if
+      // ldp-aligned-only/stp-aligned-only features are opted.
+      uint64_t MemAlignment = MemOp->getAlign().value();
+      uint64_t TypeAlignment = Align(MemOp->getSize()).value();
 
-    // If a store arrives and stp-aligned-only feature is opted, check that the
-    // alignment of the source pointer is at least double the alignment of the
-    // type.
-    if (MI.mayStore() && Subtarget->hasStpAlignedOnly() && MemOp &&
-        MemAlignment < 2 * TypeAlignment)
-      return false;
+      if (MemAlignment < 2 * TypeAlignment) {
+        NumFailedAlignmentCheck++;
+        return false;
+      }
+    }
 
     MBBI = mergePairedInsns(MBBI, Paired, Flags);
     // Collect liveness info for instructions between Prev and the new position
     // MBBI.
     for (auto I = std::next(Prev); I != MBBI; I++)
       updateDefinedRegisters(*I, DefinedInBB, TRI);
 
+    ++NumPairCreated;
+    if (TII->hasUnscaledLdStOffset(MI))
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ytmukai wrote:

This line must precede the update. I'll modify it and resubmit a patch.

https://github.com/llvm/llvm-project/pull/83948