[mlir][DialectUtils] Fix div by zero crash (llvm#153380)

Author: matthias-springer

mlir/lib/Dialect/Utils/StaticValueUtils.cpp

@@ -272,7 +272,7 @@ std::optional<int64_t> constantTripCount(OpFoldResult lb, OpFoldResult ub,
   if (!ubConstant)
     return std::nullopt;
   std::optional<int64_t> stepConstant = getConstantIntValue(step);
-  if (!stepConstant)
+  if (!stepConstant || *stepConstant == 0)
     return std::nullopt;
 
   return llvm::divideCeilSigned(*ubConstant - *lbConstant, *stepConstant);

mlir/test/Dialect/SCF/canonicalize.mlir

@@ -1925,3 +1925,16 @@ func.func @index_switch_fold_no_res() {
 
 // CHECK-LABEL: func.func @index_switch_fold_no_res()
 //  CHECK-NEXT: "test.op"() : () -> ()
+
+// -----
+
+// CHECK-LABEL: func @scf_for_all_step_size_0()
+//       CHECK:   scf.forall (%{{.*}}) = (0) to (1) step (0)
+func.func @scf_for_all_step_size_0()  {
+  %x = arith.constant 0 : index
+  scf.forall (%i, %j) = (0, 4) to (1, 5) step (%x, 8) {
+    vector.print %x : index
+    scf.forall.in_parallel {}
+  }
+  return
+}