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link.Elf: implement non-alloc {SET,SUB}_ULEB128

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David Rubin 2024-12-15 00:39:04 -08:00 • committed by Alex Rønne Petersen
parent 4162f401cb
commit 914f822025
2 changed files with 31 additions and 0 deletions
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6
src/link/Elf/Atom.zig
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@ -1882,6 +1882,9 @@ const riscv = struct {
.LO12_S,
.ADD32,
.SUB32,
.SUB_ULEB128,
.SET_ULEB128,
=> {},
else => try atom.reportUnhandledRelocError(rel, elf_file),
@ -2071,6 +2074,9 @@ const riscv = struct {
.SET6 => riscv_util.writeSetSub6(.set, code[r_offset..][0..1], S + A),
.SUB6 => riscv_util.writeSetSub6(.sub, code[r_offset..][0..1], S + A),
.SET_ULEB128 => try riscv_util.writeSetSubUleb(.set, stream, S + A),
.SUB_ULEB128 => try riscv_util.writeSetSubUleb(.sub, stream, S - A),
else => try atom.reportUnhandledRelocError(rel, elf_file),
}
}

25
src/link/riscv.zig
View file

@ -9,6 +9,31 @@ pub fn writeSetSub6(comptime op: enum { set, sub }, code: *[1]u8, addend: anytyp
mem.writeInt(u8, code, value, .little);
}
pub fn writeSetSubUleb(comptime op: enum { set, sub }, stream: *std.io.FixedBufferStream([]u8), addend: i64) !void {
switch (op) {
.set => try overwriteUleb(stream, @intCast(addend)),
.sub => {
const position = try stream.getPos();
const value: u64 = try std.leb.readUleb128(u64, stream.reader());
try stream.seekTo(position);
try overwriteUleb(stream, value -% @as(u64, @intCast(addend)));
},
}
}
fn overwriteUleb(stream: *std.io.FixedBufferStream([]u8), addend: u64) !void {
var value: u64 = addend;
const writer = stream.writer();
while (true) {
const byte = stream.buffer[stream.pos];
if (byte & 0x80 == 0) break;
try writer.writeByte(0x80 | @as(u8, @truncate(value & 0x7f)));
value >>= 7;
}
stream.buffer[stream.pos] = @truncate(value & 0x7f);
}
pub fn writeAddend(
comptime Int: type,
comptime op: enum { add, sub },