compiler_rt and mcmodel medium on freestanding RISCV build

[melko]

Zig Version

0.12.0-dev.1785+72568c131

Steps to Reproduce and Observed Behavior

While playing around with a bare-metal riscv code, I'm having a relocation linking issue related to the formatting of float values:

$ zig build-exe -mcmodel=medium zmain.zig init.s -target riscv64-freestanding-none --script memory.ld
error: ld.lld: /home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a(/home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a.o):(function __floatuntidf: .text.__floatuntidf+0x10e):
relocation R_RISCV_HI20 out of range: 524932 is not in [-524288, 524287]; references '.LCPI149_0'
    note: referenced by float_from_int.zig:0 (/home/melko/zig-linux-x86_64-0.12.0-dev.1785+72568c131/lib/compiler_rt/float_from_int.zig:0)
    note: defined in /home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a(/home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a.o)
error: ld.lld: /home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a(/home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a.o):(function __floatuntidf: .text.__floatuntidf+0x116):
relocation R_RISCV_HI20 out of range: 524833 is not in [-524288, 524287]; references '.LCPI149_1'
    note: referenced by float_from_int.zig:0 (/home/melko/zig-linux-x86_64-0.12.0-dev.1785+72568c131/lib/compiler_rt/float_from_int.zig:0)
    note: defined in /home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a(/home/melko/.cache/zig/o/df77a783dc22f5323e965e5fb77e6c22/libcompiler_rt.a.o)

As far as I understand, the mcmodel=medium flag should prevent these relocation issues, but somehow seems the flag isn't correctly forwarded to compiler_rt compilation.

If I manually build and link compiler_rt, everything works fine:

$ zig build-obj -mcmodel=medium ~/zig-linux-x86_64-0.12.0-dev.1785+72568c131/lib/compiler_rt.zig -target riscv64-freestanding-none
$ zig build-exe -mcmodel=medium zmain.zig init.s compiler_rt.o -target riscv64-freestanding-none --script memory.ld

Not sure if related to #16957

For the reference, here's the content of zmain.zig:

const std = @import("std");
const uart_addr: *volatile u32 = @ptrFromInt(0x60010004);
const uart_full: *volatile u32 = @ptrFromInt(0x60010008);

const SerialError = error{};

fn write_bytes(_: void, str: []const u8) SerialError!usize {
    print(str);
    return str.len;
}

const Serial_Writer = std.io.Writer(void, SerialError, write_bytes);
const serial_writer = @as(Serial_Writer, .{ .context = {} });

pub fn panic(message: []const u8, _: ?*std.builtin.StackTrace, _: ?usize) noreturn {
    @setCold(true);
    println("-------- PANIC --------");
    println(message);
    while (true) {}
}

pub export fn main() noreturn {
    var dd: f32 = 3;
    const ffp: *volatile f32 = ⅆ
    std.log.err("Hello {}\n\r", .{ffp.*});
    while (true) {}
}

fn putc(c: u8) void {
    while ((uart_full.* & 0b1000) != 0) {}
    uart_addr.* = c;
}

fn print(str: []const u8) void {
    for (str) |c| {
        putc(c);
    }
}

fn println(str: []const u8) void {
    print(str);
    print("\n\r");
}

pub const std_options = struct {
    pub const log_level = .info;
    pub const logFn = myLogFn;
};

pub fn myLogFn(comptime level: std.log.Level, comptime scope: @TypeOf(.enum_literal), comptime format: []const u8, args: anytype) void {
    _ = level;
    _ = scope;
    std.fmt.format(serial_writer, format, args) catch @panic("error formatting string: " ++ format);
}

init.s:

# Assembly for booting

.section .text.entry

# Declare _start used in linker.ld script

.global _start

_start:
    /* enable fpu */
    li t0, 0x6000
    csrr t1, mstatus
    or t1, t1, t0
    csrw mstatus, t1

    # Setup Stack
    la sp, boot_stack_top
    mv tp, a0

    call main

.section .bss.stack
.global boot_stack

boot_stack:
    # 1GB
    .space 1073741824

.global boot_stack_top
boot_stack_top:

and memory.ld:

/* Linker file */

/* Apply memory mapping to adapt to riscv OpenSBI */

/* Architecture */
OUTPUT_ARCH(riscv)

/* Entry Point */
ENTRY(_start)

/* OpenSBI transfer control to this address */
BASE_ADDRESS = 0x80200000;

SECTIONS
{
    . = BASE_ADDRESS;
    kernel_start = .;

    . = ALIGN(4K); /* alignment  for page size 4k */
    text_start = .;


    .text : {
        *(.text.entry)

        /* All text section off object file */
        *(.text .text.*)
    }

    . = ALIGN(4K); /* alignment  for page size 4k */
    rodata_start = .;
    .rodata : {
        *(.rodata .rodata.*)
        __debug_info_start = .;
        KEEP(*(.debug_info))
        __debug_info_end = .;
        __debug_abbrev_start = .;
        KEEP(*(.debug_abbrev))
        __debug_abbrev_end = .;
        __debug_str_start = .;
        KEEP(*(.debug_str))
        __debug_str_end = .;
        __debug_line_start = .;
        KEEP(*(.debug_line))
        __debug_line_end = .;
        __debug_ranges_start = .;
        KEEP(*(.debug_ranges))
        __debug_ranges_end = .;
    }

    . = ALIGN(4K); /* alignment  for page size 4k */
    data_start = .;
    .data : {
        *(.data .data.*)
        *(.sdata .sdata.*)
    }

    . = ALIGN(4K); /* alignment  for page size 4k */
    .stack : {
        *(.bss.stack)
    }

    . = ALIGN(4K); /* alignment  for page size 4k */
    bss_start = .;
    .bss : {
        *(.bss .bss.*)
        *(.sbss .sbss.*)
    }

    . = ALIGN(4K); /* alignment  for page size 4k */
    PROVIDE(kernel_end = .);


}

Expected Behavior

Should compile and link without errors.

[RossComputerGuy]

Yeah, I've ran into the same problem when using floating-point types. Even if I add in floating point features like f, I get the error.