[clang] [llvm] [mlir] [AMDGPU] Add the support for 45-bit buffer resource (PR #159702)

[Krzysztof Drewniak via llvm-commits]

================
@@ -11602,29 +11602,48 @@ SDValue SITargetLowering::lowerPointerAsRsrcIntrin(SDNode *Op,
   SDValue NumRecords = Op->getOperand(3);
   SDValue Flags = Op->getOperand(4);
 
-  auto [LowHalf, HighHalf] = DAG.SplitScalar(Pointer, Loc, MVT::i32, MVT::i32);
-  SDValue Mask = DAG.getConstant(0x0000ffff, Loc, MVT::i32);
-  SDValue Masked = DAG.getNode(ISD::AND, Loc, MVT::i32, HighHalf, Mask);
-  std::optional<uint32_t> ConstStride = std::nullopt;
-  if (auto *ConstNode = dyn_cast<ConstantSDNode>(Stride))
-    ConstStride = ConstNode->getZExtValue();
-
-  SDValue NewHighHalf = Masked;
-  if (!ConstStride || *ConstStride != 0) {
-    SDValue ShiftedStride;
-    if (ConstStride) {
-      ShiftedStride = DAG.getConstant(*ConstStride << 16, Loc, MVT::i32);
-    } else {
-      SDValue ExtStride = DAG.getAnyExtOrTrunc(Stride, Loc, MVT::i32);
-      ShiftedStride =
-          DAG.getNode(ISD::SHL, Loc, MVT::i32, ExtStride,
-                      DAG.getShiftAmountConstant(16, MVT::i32, Loc));
-    }
-    NewHighHalf = DAG.getNode(ISD::OR, Loc, MVT::i32, Masked, ShiftedStride);
+  SDValue Rsrc;
+
+  if (Subtarget->has45BitNumRecordsBufferResource()) {
+    // Build the lower 64-bit value, which has a 57-bit base and the lower 7-bit
+    // num_records.
+    SDValue ExtPointer = DAG.getAnyExtOrTrunc(Pointer, Loc, MVT::i64);
+    SDValue NumRecordsLHS =
+        DAG.getNode(ISD::SHL, Loc, MVT::i64, NumRecords,
+                    DAG.getShiftAmountConstant(57, MVT::i32, Loc));
+    SDValue LowHalf =
+        DAG.getNode(ISD::OR, Loc, MVT::i64, ExtPointer, NumRecordsLHS);
+
+    // Build the higher 64-bit value, which has the higher 38-bit num_records,
+    // 6-bit zero (omit), 14-bit stride and 6-bit zero (omit).
----------------
krzysz00 wrote:

```suggestion
    // 6-bit zero (omit), 16-bit stride + modifier and 6-bit zero (omit).
```

https://github.com/llvm/llvm-project/pull/159702