x86_64 backend miscompilation

[andrewrk]

Zig Version

0.14.0-dev.2545+e2e363361

Steps to Reproduce and Observed Behavior

Obtain master branch stage3.

git checkout x86-miscomp-repro
stage3/bin/zig build -p self -Duse-llvm=false  --prominent-compile-errors -Dno-lib -Ddev=wasm
self/bin/zig build-exe ../test/standalone/simple/hello_world/hello.zig -target wasm32-wasi --debug-log link

Observe:

debug(link): updateExports '_start' nav=117
debug(link): flush export '_start' nav=InternPool.Nav.Index(117)
thread 862392 panic: integer overflow
Unwind error at address `exe:0x182c3b2` (error.AddressOutOfRange), trace may be incomplete

/home/andy/dev/zig/src/link/Wasm/Flush.zig:303:20: 0x159d037 in finish (main.zig)
            offset += size;
                   ^
/home/andy/dev/zig/src/link/Wasm.zig:2787:36: 0x15a85d1 in flushModule (main.zig)
    return wasm.flush_buffer.finish(wasm) catch |err| switch (err) {
                                   ^
/home/andy/dev/zig/src/link/Wasm.zig:2511:28: 0x13f336c in flush (main.zig)
    return wasm.flushModule(arena, tid, prog_node);
                           ^
/home/andy/dev/zig/src/link.zig:790:77: 0x1295f4d in flush (main.zig)
                return @as(*tag.Type(), @fieldParentPtr("base", base)).flush(arena, tid, prog_node);
                                                                            ^
/home/andy/dev/zig/src/Compilation.zig:2430:17: 0x11ba0ea in flush (main.zig)
        lf.flush(arena, tid, prog_node) catch |err| switch (err) {
                ^
/home/andy/dev/zig/src/Compilation.zig:2390:22: 0x11bfa9f in update (main.zig)
            try flush(comp, arena, .{
                     ^
/home/andy/dev/zig/src/main.zig:4450:20: 0x11f00ed in updateModule (main.zig)
    try comp.update(prog_node);
                   ^
/home/andy/dev/zig/src/main.zig:3640:21: 0x120898d in buildOutputType (main.zig)
        updateModule(comp, color, root_prog_node) catch |err| switch (err) {
                    ^
/home/andy/dev/zig/src/main.zig:268:31: 0x121f6ea in mainArgs (main.zig)
        return buildOutputType(gpa, arena, args, .{ .build = .Exe });
                              ^
/home/andy/dev/zig/src/main.zig:209:20: 0x11849de in main (main.zig)
    return mainArgs(gpa, arena, args);
                   ^
/home/andy/dev/zig/lib/std/start.zig:656:37: 0x11825a9 in posixCallMainAndExit (std.zig)
            const result = root.main() catch |err| {
                                    ^
/home/andy/dev/zig/lib/std/start.zig:271:5: 0x1182016 in _start (std.zig)
    asm volatile (switch (native_arch) {
    ^
fish: Job 1, 'self/bin/zig build-exe ../test/…' terminated by signal SIGABRT (Abort)

Expected Behavior

The same as the LLVM backend:

debug(link): updateExports '_start' nav=117
debug(link): flush export '_start' nav=InternPool.Nav.Index(117)
debug(link): total memory pages: 257
debug(link): Writing type section. Count: (9)
thread 862909 panic: attempt to use null value
/home/andy/dev/zig/src/link/Wasm.zig:3465:54: 0x1895667 in navAddr (zig)
    return wasm.flush_buffer.data_segments.get(ds_id).?;
                                                     ^
/home/andy/dev/zig/src/arch/wasm/Emit.zig:972:38: 0x1894fe5 in navRefOff (zig)
            const addr = wasm.navAddr(data.nav_index);
                                     ^
/home/andy/dev/zig/src/arch/wasm/Emit.zig:70:26: 0x173b816 in lowerToCode (zig)
            try navRefOff(wasm, code, .{ .nav_index = datas[inst].nav_index, .offset = 0 }, is_wasm32);
                         ^
/home/andy/dev/zig/src/arch/wasm/CodeGen.zig:1219:29: 0x1606a77 in lower (zig)
        try emit.lowerToCode();
                            ^
/home/andy/dev/zig/src/link/Wasm/Flush.zig:648:35: 0x15ff6f9 in finish (zig)
                try function.lower(wasm, binary_bytes);
                                  ^
/home/andy/dev/zig/src/link/Wasm.zig:2787:36: 0x14ed243 in flushModule (zig)
    return wasm.flush_buffer.finish(wasm) catch |err| switch (err) {
                                   ^
/home/andy/dev/zig/src/link/Wasm.zig:2511:28: 0x13f904f in flush (zig)
    return wasm.flushModule(arena, tid, prog_node);
                           ^
/home/andy/dev/zig/src/link.zig:790:77: 0x131beeb in flush (zig)
                return @as(*tag.Type(), @fieldParentPtr("base", base)).flush(arena, tid, prog_node);
                                                                            ^
/home/andy/dev/zig/src/Compilation.zig:2430:17: 0x131bd42 in flush (zig)
        lf.flush(arena, tid, prog_node) catch |err| switch (err) {
                ^
/home/andy/dev/zig/src/Compilation.zig:2390:22: 0x131ec25 in update (zig)
            try flush(comp, arena, .{
                     ^
/home/andy/dev/zig/src/main.zig:4450:20: 0x135595d in updateModule (zig)
    try comp.update(prog_node);
                   ^
/home/andy/dev/zig/src/main.zig:3640:21: 0x136e025 in buildOutputType (zig)
        updateModule(comp, color, root_prog_node) catch |err| switch (err) {
                    ^
/home/andy/dev/zig/src/main.zig:268:31: 0x12bbc69 in mainArgs (zig)
        return buildOutputType(gpa, arena, args, .{ .build = .Exe });
                              ^
/home/andy/dev/zig/src/main.zig:209:20: 0x12b90ca in main (zig)
    return mainArgs(gpa, arena, args);
                   ^
/home/andy/dev/zig/lib/std/start.zig:656:37: 0x12b8952 in posixCallMainAndExit (zig)
            const result = root.main() catch |err| {
                                    ^
/home/andy/dev/zig/lib/std/start.zig:271:5: 0x12b853d in _start (zig)
    asm volatile (switch (native_arch) {
    ^
???:?:?: 0x0 in ??? (???)
fish: Job 1, 'stage4/bin/zig build-exe ../tes…' terminated by signal SIGABRT (Abort)

[andrewrk]

Duplicate of #20095