[llvm] [RISCV][ISEL] Lowering to load-acquire/store-release for RISCV Zalasr (PR #82914)

[Wang Pengcheng via llvm-commits]

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@@ -105,22 +105,65 @@ defm AMOMAXU_D  : AMO_rr_aq_rl<0b11100, 0b011, "amomaxu.d">,
 // Pseudo-instructions and codegen patterns
 //===----------------------------------------------------------------------===//
 
+let IsAtomic = 1 in {
+// An atomic load operation that does not need either acquire or release
+// semantics.
+class relaxed_load<PatFrags base>
+    : PatFrag<(ops node:$ptr), (base node:$ptr)> {
+  let IsAtomicOrderingAcquireOrStronger = 0;
+}
+
+// A atomic load operation that actually needs acquire semantics.
+class acquiring_load<PatFrags base>
+    : PatFrag<(ops node:$ptr), (base node:$ptr)> {
+  let IsAtomicOrderingAcquire = 1;
+}
+
+// An atomic load operation that needs sequential consistency.
+class seq_cst_load<PatFrags base>
+    : PatFrag<(ops node:$ptr), (base node:$ptr)> {
+  let IsAtomicOrderingSequentiallyConsistent = 1;
+}
+
+// An atomic store operation that does not need either acquire or release
+// semantics.
+class relaxed_store<PatFrag base>
+    : PatFrag<(ops node:$val, node:$ptr), (base node:$val, node:$ptr)> {
+  let IsAtomicOrderingReleaseOrStronger = 0;
+}
+
+// A store operation that actually needs release semantics.
+class releasing_store<PatFrag base>
+    : PatFrag<(ops node:$val, node:$ptr), (base node:$val, node:$ptr)> {
+  let IsAtomicOrderingRelease = 1;
+}
+
+// A store operation that actually needs sequential consistency.
+class seq_cst_store<PatFrag base>
+    : PatFrag<(ops node:$val, node:$ptr), (base node:$val, node:$ptr)> {
+  let IsAtomicOrderingSequentiallyConsistent = 1;
+}
+} // IsAtomic = 1
+
 // Atomic load/store are available under both +a and +force-atomics.
 // Fences will be inserted for atomic load/stores according to the logic in
 // RISCVTargetLowering::{emitLeadingFence,emitTrailingFence}.
+// The normal loads/store are relaxed (unordered) loads that don't have any
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wangpc-pp wrote:

`are relaxed (unordered) loads` -> `are relaxed (unordered) ones`, or just remove it?

https://github.com/llvm/llvm-project/pull/82914