[PATCH] D156558: [mlir][ArmSME] Remove "pure" side-effect from 'get_tile_id' op to prevent CSE

[Cullen Rhodes via Phabricator via llvm-commits]

c-rhodes created this revision.
c-rhodes added reviewers: awarzynski, benmxwl-arm.
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The 'get_tile_id' op is currently marked as pure so CSE thinks these ops
are equivalent and replaces with them a single one. This patch removes
pure to prevent this.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D156558

Files:
  mlir/include/mlir/Dialect/ArmSME/IR/ArmSME.td
  mlir/test/Dialect/ArmSME/cse.mlir


Index: mlir/test/Dialect/ArmSME/cse.mlir
===================================================================
--- /dev/null
+++ mlir/test/Dialect/ArmSME/cse.mlir
@@ -0,0 +1,16 @@
+// RUN: mlir-opt -allow-unregistered-dialect %s -pass-pipeline='builtin.module(func.func(cse))' | FileCheck %s
+
+// This test is checking that CSE does not remove 'arm_sme.get_tile_id' ops as
+// duplicates.
+// CHECK-LABEL: @get_tile_id
+// CHECK: %[[TILE_ID_0:.*]] = arm_sme.get_tile_id : i32
+// CHECK: %[[TILE_ID_1:.*]] = arm_sme.get_tile_id : i32
+// CHECK: "prevent.dce"(%[[TILE_ID_0]]) : (i32) -> ()
+// CHECK: "prevent.dce"(%[[TILE_ID_1]]) : (i32) -> ()
+func.func @get_tile_id() {
+  %tile_id_1 = arm_sme.get_tile_id : i32
+  %tile_id_2 = arm_sme.get_tile_id : i32
+  "prevent.dce"(%tile_id_1) : (i32) -> ()
+  "prevent.dce"(%tile_id_2) : (i32) -> ()
+  return
+}
Index: mlir/include/mlir/Dialect/ArmSME/IR/ArmSME.td
===================================================================
--- mlir/include/mlir/Dialect/ArmSME/IR/ArmSME.td
+++ mlir/include/mlir/Dialect/ArmSME/IR/ArmSME.td
@@ -162,7 +162,7 @@
   let hasCanonicalizeMethod = 1;
 }
 
-def GetTileID : ArmSME_Op<"get_tile_id", [Pure]> {
+def GetTileID : ArmSME_Op<"get_tile_id"> {
   let summary = "Returns an SME \"virtual tile\" id";
   let description = [{
     A `get_tile_id` operation returns a scalar integer representing an SME


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