[llvm] [LSR] Recognize vscale-relative immediates (PR #88124)

[Graham Hunter via llvm-commits]

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@@ -4004,27 +4160,29 @@ void LSRInstance::GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx,
     if (!ConstantInt::isValueValidForType(IntTy, Factor))
       continue;
     // Check that the multiplication doesn't overflow.
-    if (Base.BaseOffset == std::numeric_limits<int64_t>::min() && Factor == -1)
+    if (Base.BaseOffset.isMin() && Factor == -1)
       continue;
-    int64_t NewBaseOffset = (uint64_t)Base.BaseOffset * Factor;
+    Immediate NewBaseOffset =
+        Immediate::getFixed((uint64_t)Base.BaseOffset.getFixedValue() * Factor);
     assert(Factor != 0 && "Zero factor not expected!");
-    if (NewBaseOffset / Factor != Base.BaseOffset)
+    if (NewBaseOffset.getFixedValue() / Factor !=
+        Base.BaseOffset.getFixedValue())
       continue;
     // If the offset will be truncated at this use, check that it is in bounds.
     if (!IntTy->isPointerTy() &&
-        !ConstantInt::isValueValidForType(IntTy, NewBaseOffset))
+        !ConstantInt::isValueValidForType(IntTy, NewBaseOffset.getFixedValue()))
       continue;
 
     // Check that multiplying with the use offset doesn't overflow.
-    int64_t Offset = LU.MinOffset;
-    if (Offset == std::numeric_limits<int64_t>::min() && Factor == -1)
+    Immediate Offset = LU.MinOffset;
+    if (Offset.isMin() && Factor == -1)
       continue;
-    Offset = (uint64_t)Offset * Factor;
-    if (Offset / Factor != LU.MinOffset)
+    Offset = Immediate::getFixed((uint64_t)Offset.getFixedValue() * Factor);
+    if (Offset.getFixedValue() / Factor != LU.MinOffset.getFixedValue())
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huntergr-arm wrote:

Fixed specific, it's generating terms for ICmpZero uses (for which we won't have any legal scalable offsets)

https://github.com/llvm/llvm-project/pull/88124