[mlir][IntRangeInference] Fix arith.ceildivsi range inference when it includes INT_MIN (llvm#121062)

There is a special case in `arith.ceildivsi` range inference for
handling `lhs.smin()==INT_MIN`, but when `lhs` is not a single value, it
can cause it to skip entire negative range. Add `lhs.smin() + 1` check
to handle it.

Author: Hardcode84

mlir/lib/Interfaces/Utils/InferIntRangeCommon.cpp

@@ -386,7 +386,15 @@ mlir::intrange::inferCeilDivS(ArrayRef<ConstantIntRanges> argRanges) {
     }
     return result;
   };
-  return inferDivSRange(lhs, rhs, ceilDivSIFix);
+  ConstantIntRanges result = inferDivSRange(lhs, rhs, ceilDivSIFix);
+  if (lhs.smin().isMinSignedValue() && lhs.smax().sgt(lhs.smin())) {
+    // If lhs range includes INT_MIN and lhs is not a single value, we can
+    // suddenly wrap to positive val, skipping entire negative range, add
+    // [INT_MIN + 1, smax()] range to the result to handle this.
+    auto newLhs = ConstantIntRanges::fromSigned(lhs.smin() + 1, lhs.smax());
+    result = result.rangeUnion(inferDivSRange(newLhs, rhs, ceilDivSIFix));
+  }
+  return result;
 }
 
 ConstantIntRanges

mlir/test/Dialect/Arith/int-range-interface.mlir

@@ -249,6 +249,18 @@ func.func @ceil_divsi(%arg0 : index) -> i1 {
     func.return %10 : i1
 }
 
+// There was a bug, which was causing this expr errorneously fold to constant
+// CHECK-LABEL: func @ceil_divsi_full_range
+// CHECK-SAME: (%[[arg:.*]]: index)
+// CHECK: %[[c64:.*]] = arith.constant 64 : index
+// CHECK: %[[ret:.*]] = arith.ceildivsi %[[arg]], %[[c64]] : index
+// CHECK: return %[[ret]]
+func.func @ceil_divsi_full_range(%6: index) -> index {
+  %c64 = arith.constant 64 : index
+  %55 = arith.ceildivsi %6, %c64 : index
+  return %55 : index
+}
+
 // CHECK-LABEL: func @ceil_divsi_intmin_bug_115293
 // CHECK: %[[ret:.*]] = arith.constant true
 // CHECK: return %[[ret]]