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work around llvm failing to lower memcpy

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triggers an assertion in LegalizeDAG otherwise
This commit is contained in:
Andrew Kelley 2025-01-17 13:21:30 -08:00
parent 59acfb1263
commit acf7043955
1 changed files with 26 additions and 2 deletions
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28
lib/compiler_rt/memcpy.zig
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@ -9,12 +9,36 @@ comptime {
}
}
const llvm_cannot_lower = switch (builtin.cpu.arch) {
.arm, .armeb, .thumb, .thumbeb => builtin.zig_backend == .stage2_llvm,
else => false,
};
fn memcpy(noalias opt_dest: ?[*]u8, noalias opt_src: ?[*]const u8, len: usize) callconv(.C) ?[*]u8 {
return memmove(opt_dest, opt_src, len);
if (llvm_cannot_lower) {
for (0..len) |i| opt_dest.?[i] = opt_src.?[i];
return opt_dest;
} else {
return memmove(opt_dest, opt_src, len);
}
}
/// A port of https://github.com/facebook/folly/blob/1c8bc50e88804e2a7361a57cd9b551dd10f6c5fd/folly/memcpy.S
fn memmove(opt_dest: ?[*]u8, opt_src: ?[*]const u8, len: usize) callconv(.C) ?[*]u8 {
// a port of https://github.com/facebook/folly/blob/1c8bc50e88804e2a7361a57cd9b551dd10f6c5fd/folly/memcpy.S
if (llvm_cannot_lower) {
if (@intFromPtr(opt_dest) < @intFromPtr(opt_src)) {
for (0..len) |i| opt_dest.?[i] = opt_src.?[i];
return opt_dest;
} else {
var index = len;
while (index != 0) {
index -= 1;
opt_dest.?[index] = opt_src.?[index];
}
return opt_dest;
}
}
if (len == 0) {
@branchHint(.unlikely);
return opt_dest;