Unexpected extra lines getting printed out with hcl.print

[jcasas00]

def test_print_extra_output():
    hcl.init()
    def kernel():
        x = hcl.scalar(1, "x", dtype=hcl.UInt(8))
        y = hcl.scalar(2, "y", dtype=hcl.UInt(8))
        hcl.print(x.v, "x = %d\n")
        hcl.print(y.v, "y = %d\n")

        r = hcl.compute((1,), lambda _:0, dtype=hcl.UInt(32))
        return r
    s = hcl.create_schedule([], kernel)
    hcl_res = hcl.asarray(np.zeros((1,), dtype=np.uint32), dtype=hcl.UInt(32))
    f = hcl.build(s)
    f(hcl_res)

When I run this code, I get:

hcl-dialect-prototype/build/tools/hcl/python_packages/hcl_core/hcl_mlir/exceptions.py:70: RuntimeWarning: [API] LLVM_BUILD_DIR is not set, print memref feature is not available. warnings.warn(self.message, category=self.category) x = 1 y = 2 x = 0 <---- not expecting this output

If either of the hcl.print calls is commented out, that 3rd line is not generated.

[zzzDavid]

Seems to be an issue with the call operation. To reproduce this issue, the IR is:

// RUN: hcl-opt --lower-print-ops --jit %s

module {
  func.func @top() -> () {
    %x = arith.constant 0 : i32
    hcl.print(%x) {format="x: %d \n"} : i32
    %y = arith.constant 1 : i32
    hcl.print(%y) {format="y: %d \n"} : i32
    return
  }
}

And the lowered LLVM IR is:

module {
  llvm.mlir.global internal constant @frmt_spec1("y: %.0f \0A")
  llvm.mlir.global internal constant @frmt_spec0("x: %.0f \0A")
  llvm.func @printf(!llvm.ptr<i8>, ...) -> i32
  llvm.func @top() {
    %0 = llvm.mlir.constant(0 : i32) : i32
    %1 = llvm.mlir.addressof @frmt_spec0 : !llvm.ptr<array<9 x i8>>
    %2 = llvm.mlir.constant(0 : index) : i64
    %3 = llvm.getelementptr %1[%2, %2] : (!llvm.ptr<array<9 x i8>>, i64, i64) -> !llvm.ptr<i8>
    %4 = llvm.mlir.constant(0 : i64) : i64
    %5 = llvm.sitofp %4 : i64 to f64
    %6 = llvm.call @printf(%3, %5) : (!llvm.ptr<i8>, f64) -> i32
    %7 = llvm.mlir.constant(1 : i32) : i32
    %8 = llvm.mlir.addressof @frmt_spec1 : !llvm.ptr<array<9 x i8>>
    %9 = llvm.mlir.constant(0 : index) : i64
    %10 = llvm.getelementptr %8[%9, %9] : (!llvm.ptr<array<9 x i8>>, i64, i64) -> !llvm.ptr<i8>
    %11 = llvm.mlir.constant(1 : i64) : i64
    %12 = llvm.sitofp %11 : i64 to f64
    %13 = llvm.call @printf(%10, %12) : (!llvm.ptr<i8>, f64) -> i32
    llvm.return
  }
}

The lowered LLVM dialect IR seems correct, looking into what's causing this issue

[zzzDavid]

I figured it out, it's the alignment issue of global string, e.g. llvm.mlir.global internal constant @frmt_spec1("y: %.0f \0A"). llvm.getelementptr would get the next global string, so there's an extra print.

[jcasas00]

Still seeing extra outputs.

    def kernel():
        z = hcl.scalar(3, "z", dtype=hcl.UInt(16))
        hcl.print((z.v), "zz=%d ")
        hcl.print((z.v,z.v), "aaaaaaaaaaaaa=%d bbbbbbbb=%d")
        hcl.print((), "    \n")
        #
        r = hcl.compute((1,), lambda _:0, dtype=hcl.UInt(32))
        return r

generates the output:

zz=3 aaaaaaaaaaaaa=3 bbbbbbbb=3zz=0 

Note the extra characters after the first "zz=3" and "zz=0" appears at the end. Seems like there's some overflow happening with the lines that doesn't end with a \n.

[zzzDavid]

LLVM string requires a terminator \00, the same as the \0 in C string. I encounter the same issue with reading/writing files, a more detailed description is here: https://github.com/zzzDavid/hcl-debug/tree/main/read_write_file

This issue will be closed after test cases are added.

[zzzDavid]

Fixed by cornell-zhang/heterocl@90be1921a3ca94e68676a4b68a8227dff5938453