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Printf to llvm

printf_to_llvm

i8 = builtin.IntegerType(8) module-attribute

PrintlnOpToPrintfCall

Bases: RewritePattern

Source code in xdsl/transforms/printf_to_llvm.py 
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class PrintlnOpToPrintfCall(RewritePattern):
    collected_global_symbs: dict[str, llvm.GlobalOp]

    def __init__(self):
        self.collected_global_symbs = dict()

    def _construct_global(self, val: str):
        """
        Constructs an llvm.global operation containing the string. Assigns a unique
        symbol name to the value that is derived from the string value.
        """
        data = val.encode() + b"\x00"

        t_type = builtin.TensorType(i8, [len(data)])

        return llvm.GlobalOp(
            llvm.LLVMArrayType(len(data), i8),
            _key_from_str(val),
            constant=True,
            linkage="internal",
            value=builtin.DenseIntOrFPElementsAttr(t_type, builtin.BytesAttr(data)),
        )

    @op_type_rewrite_pattern
    def match_and_rewrite(self, op: printf.PrintFormatOp, rewriter: PatternRewriter, /):
        format_str = ""
        args: list[SSAValue] = []
        casts: list[Operation] = []
        # make sure all arguments are in the format libc expects them to be
        # e.g. floats must be promoted to double before calling
        for part in _format_string_spec_from_print_op(op):
            if isinstance(part, str):
                format_str += part
            elif isinstance(part.type, builtin.IndexType):
                # index must be cast to fixed bitwidth before printing
                casts.append(new_val := arith.IndexCastOp(part, builtin.i64))
                args.append(new_val.result)
                format_str += "%li"
            elif part.type == builtin.f32:
                # f32 must be promoted to f64 before printing
                casts.append(new_val := arith.ExtFOp(part, builtin.f64))
                args.append(new_val.result)
                format_str += "%f"
            else:
                args.append(part)
                format_str += _format_str_for_type(part.type)

        globl = self._construct_global(format_str)
        self.collected_global_symbs[globl.sym_name.data] = globl

        rewriter.replace_op(
            op,
            casts
            + [
                ptr := llvm.AddressOfOp(globl.sym_name, llvm.LLVMPointerType()),
                llvm.CallOp("printf", ptr.result, *args, variadic_args=len(args)),
            ],
        )

collected_global_symbs: dict[str, llvm.GlobalOp] = dict() instance-attribute

__init__()

Source code in xdsl/transforms/printf_to_llvm.py 
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def __init__(self):
    self.collected_global_symbs = dict()

match_and_rewrite(op: printf.PrintFormatOp, rewriter: PatternRewriter)

Source code in xdsl/transforms/printf_to_llvm.py 
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@op_type_rewrite_pattern
def match_and_rewrite(self, op: printf.PrintFormatOp, rewriter: PatternRewriter, /):
    format_str = ""
    args: list[SSAValue] = []
    casts: list[Operation] = []
    # make sure all arguments are in the format libc expects them to be
    # e.g. floats must be promoted to double before calling
    for part in _format_string_spec_from_print_op(op):
        if isinstance(part, str):
            format_str += part
        elif isinstance(part.type, builtin.IndexType):
            # index must be cast to fixed bitwidth before printing
            casts.append(new_val := arith.IndexCastOp(part, builtin.i64))
            args.append(new_val.result)
            format_str += "%li"
        elif part.type == builtin.f32:
            # f32 must be promoted to f64 before printing
            casts.append(new_val := arith.ExtFOp(part, builtin.f64))
            args.append(new_val.result)
            format_str += "%f"
        else:
            args.append(part)
            format_str += _format_str_for_type(part.type)

    globl = self._construct_global(format_str)
    self.collected_global_symbs[globl.sym_name.data] = globl

    rewriter.replace_op(
        op,
        casts
        + [
            ptr := llvm.AddressOfOp(globl.sym_name, llvm.LLVMPointerType()),
            llvm.CallOp("printf", ptr.result, *args, variadic_args=len(args)),
        ],
    )

PrintfToLLVM dataclass

Bases: ModulePass

Source code in xdsl/transforms/printf_to_llvm.py 
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class PrintfToLLVM(ModulePass):
    name = "printf-to-llvm"

    def apply(self, ctx: Context, op: builtin.ModuleOp) -> None:
        add_printf_call = PrintlnOpToPrintfCall()

        PatternRewriteWalker(add_printf_call).rewrite_module(op)

        if not add_printf_call.collected_global_symbs:
            return

        op.body.block.add_ops(
            [
                llvm.FuncOp(
                    "printf",
                    llvm.LLVMFunctionType([llvm.LLVMPointerType()], is_variadic=True),
                    linkage=llvm.LinkageAttr("external"),
                ),
                *add_printf_call.collected_global_symbs.values(),
            ]
        )

name = 'printf-to-llvm' class-attribute instance-attribute

apply(ctx: Context, op: builtin.ModuleOp) -> None

Source code in xdsl/transforms/printf_to_llvm.py 
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def apply(self, ctx: Context, op: builtin.ModuleOp) -> None:
    add_printf_call = PrintlnOpToPrintfCall()

    PatternRewriteWalker(add_printf_call).rewrite_module(op)

    if not add_printf_call.collected_global_symbs:
        return

    op.body.block.add_ops(
        [
            llvm.FuncOp(
                "printf",
                llvm.LLVMFunctionType([llvm.LLVMPointerType()], is_variadic=True),
                linkage=llvm.LinkageAttr("external"),
            ),
            *add_printf_call.collected_global_symbs.values(),
        ]
    )

legalize_str_for_symbol_name(val: str)

Takes any string and legalizes it to be a global llvm symbol. (for the strictest possible interpretation of this)

  • Replaces all whitespaces and dots with _
  • Deletes all non ascii alphanumerical characters
  • Strips all underscores from the start and end of the string

The resulting string consists only of ascii letters, underscores and digits.

This is a surjective mapping, meaning that multiple inputs will produce the same output. This function alone cannot be used to get a uniquely identifying global symbol name for a string!

Source code in xdsl/transforms/printf_to_llvm.py 
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def legalize_str_for_symbol_name(val: str):
    """
    Takes any string and legalizes it to be a global llvm symbol.
    (for the strictest possible interpretation of this)

     - Replaces all whitespaces and dots with _
     - Deletes all non ascii alphanumerical characters
     - Strips all underscores from the start and end of the string

    The resulting string consists only of ascii letters, underscores and digits.

    This is a surjective mapping, meaning that multiple inputs will produce the same
    output. This function alone cannot be used to get a uniquely identifying global
    symbol name for a string!
    """
    val = re.sub(r"(\s+|\.)", "_", val)
    val = re.sub(r"[^A-Za-z0-9_]+", "", val).strip("_")
    return val