Fix getFinalValue() to be able to handle values that are loop induction variables (#4565)

Fixes issue #4556.

---------

Signed-off-by: Tiotto, Ettore <[email protected]>
Signed-off-by: Whitney Tsang <[email protected]>
Co-authored-by: Whitney Tsang <[email protected]>

Author: etiotto

test/Triton/Intel/RemoveMasks/regressions.mlir

@@ -0,0 +1,22 @@
+// RUN: triton-opt %s -triton-intel-remove-masks | FileCheck %s
+
+module {
+  // COM: Regression test for issue #4556.
+  // COM: Ensure test compiles without triggering an assertion.
+  tt.func public @issue_4556(%arg0: tensor<16x1x1x!tt.ptr<f32>>) {
+    // CHECK-LABEL: issue_4556
+    %c0_i32 = arith.constant 0 : i32
+    %c1_i32 = arith.constant 1 : i32
+    %c196_i32 = arith.constant 196 : i32
+    %cst_0 = arith.constant dense<0.000000e+00> : tensor<16x1x1xf32>
+    %cst_196 = arith.constant dense<196> : tensor<1x1x1xi32>
+    scf.for %iv = %c0_i32 to %c196_i32 step %c1_i32 : i32 {
+      %0 = tt.splat %iv : i32 -> tensor<1x1x1xi32>
+      %1 = arith.cmpi slt, %0, %cst_196 : tensor<1x1x1xi32>
+      %mask = tt.broadcast %1 : tensor<1x1x1xi1> -> tensor<16x1x1xi1>
+      %2 = tt.load %arg0, %mask, %cst_0 : tensor<16x1x1x!tt.ptr<f32>>
+      scf.yield
+    }
+    tt.return
+  }
+}

third_party/intel/lib/Utils/Utility.cpp

@@ -147,6 +147,9 @@ Value getFinalValue(Value value) {
     BlockArgument blockArg = cast<BlockArgument>(value);
     Operation *parentOp = blockArg.getOwner()->getParentOp();
     if (scf::ForOp forOp = dyn_cast<scf::ForOp>(parentOp)) {
+      if (blockArg == forOp.getInductionVar())
+        return value;
+
       int numIVs = forOp.getNumInductionVars();
       int initArgIdx = blockArg.getArgNumber() - numIVs;
       auto initArgs = forOp.getInitArgs();