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Merge pull request #21056 from alexrp/start-fix-precedence
`start`: Avoid string concatenation in inline asm.
This commit is contained in:
Andrew Kelley
GitHub
commit
b917d778c6
@ -232,6 +232,16 @@ fn _start() callconv(.Naked) noreturn {
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);
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}
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// Move this to the riscv prong below when this is resolved: https://github.com/ziglang/zig/issues/20918
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if (builtin.cpu.arch.isRISCV() and builtin.zig_backend != .stage2_riscv64) asm volatile (
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\\ .weak __global_pointer$
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\\ .hidden __global_pointer$
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\\ .option push
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\\ .option norelax
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\\ lla gp, __global_pointer$
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\\ .option pop
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);
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// Note that we maintain a very low level of trust with regards to ABI guarantees at this point.
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// We will redundantly align the stack, clear the link register, etc. While e.g. the Linux
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// kernel is usually good about upholding the ABI guarantees, the same cannot be said of dynamic
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@ -275,24 +285,19 @@ fn _start() callconv(.Naked) noreturn {
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\\ and sp, #-16
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\\ b %[posixCallMainAndExit]
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,
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// zig fmt: off
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.csky =>
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if (builtin.position_independent_code)
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// The CSKY ABI assumes that `gb` is set to the address of the GOT in order for
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// position-independent code to work. We depend on this in `std.os.linux.start_pie`
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// to locate `_DYNAMIC` as well.
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\\ grs t0, 1f
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\\ 1:
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\\ lrw gb, 1b@GOTPC
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\\ addu gb, t0
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else ""
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++
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// The CSKY ABI assumes that `gb` is set to the address of the GOT in order for
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// position-independent code to work. We depend on this in `std.os.linux.start_pie`
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// to locate `_DYNAMIC` as well.
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\\ grs t0, 1f
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\\ 1:
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\\ lrw gb, 1b@GOTPC
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\\ addu gb, t0
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\\ movi lr, 0
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\\ mov a0, sp
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\\ andi sp, sp, -8
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\\ jmpi %[posixCallMainAndExit]
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,
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// zig fmt: on
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.hexagon =>
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// r29 = SP, r30 = FP
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\\ r30 = #0
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@ -308,27 +313,13 @@ fn _start() callconv(.Naked) noreturn {
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\\ bstrins.d $sp, $zero, 3, 0
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\\ b %[posixCallMainAndExit]
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,
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// zig fmt: off
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.riscv32, .riscv64 =>
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// The self-hosted riscv64 backend is not able to assemble this yet.
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if (builtin.zig_backend != .stage2_riscv64)
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// The RISC-V ELF ABI assumes that `gp` is set to the value of `__global_pointer$` at
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// startup in order for GP relaxation to work, even in static builds.
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\\ .weak __global_pointer$
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\\ .hidden __global_pointer$
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\\ .option push
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\\ .option norelax
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\\ lla gp, __global_pointer$
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\\ .option pop
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else ""
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++
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\\ li s0, 0
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\\ li ra, 0
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\\ mv a0, sp
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\\ andi sp, sp, -16
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\\ tail %[posixCallMainAndExit]@plt
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,
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// zig fmt: on
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.m68k =>
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// Note that the - 8 is needed because pc in the jsr instruction points into the middle
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// of the jsr instruction. (The lea is 6 bytes, the jsr is 4 bytes.)
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@ -2909,7 +2909,17 @@ pub const Object = struct {
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function_index.setAlignment(resolved.alignment.toLlvm(), &o.builder);
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// Function attributes that are independent of analysis results of the function body.
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try o.addCommonFnAttributes(&attributes, owner_mod);
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try o.addCommonFnAttributes(
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&attributes,
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owner_mod,
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// Some backends don't respect the `naked` attribute in `TargetFrameLowering::hasFP()`,
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// so for these backends, LLVM will happily emit code that accesses the stack through
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// the frame pointer. This is nonsensical since what the `naked` attribute does is
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// suppress generation of the prologue and epilogue, and the prologue is where the
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// frame pointer normally gets set up. At time of writing, this is the case for at
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// least x86 and RISC-V.
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owner_mod.omit_frame_pointer or fn_info.cc == .Naked,
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);
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if (fn_info.return_type == .noreturn_type) try attributes.addFnAttr(.noreturn, &o.builder);
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@ -2956,13 +2966,14 @@ pub const Object = struct {
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o: *Object,
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attributes: *Builder.FunctionAttributes.Wip,
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owner_mod: *Package.Module,
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omit_frame_pointer: bool,
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) Allocator.Error!void {
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const comp = o.pt.zcu.comp;
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if (!owner_mod.red_zone) {
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try attributes.addFnAttr(.noredzone, &o.builder);
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}
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if (owner_mod.omit_frame_pointer) {
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if (omit_frame_pointer) {
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try attributes.addFnAttr(.{ .string = .{
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.kind = try o.builder.string("frame-pointer"),
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.value = try o.builder.string("none"),
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@ -4528,7 +4539,7 @@ pub const Object = struct {
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var attributes: Builder.FunctionAttributes.Wip = .{};
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defer attributes.deinit(&o.builder);
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try o.addCommonFnAttributes(&attributes, zcu.root_mod);
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try o.addCommonFnAttributes(&attributes, zcu.root_mod, zcu.root_mod.omit_frame_pointer);
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function_index.setLinkage(.internal, &o.builder);
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function_index.setCallConv(.fastcc, &o.builder);
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@ -4557,7 +4568,7 @@ pub const Object = struct {
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var attributes: Builder.FunctionAttributes.Wip = .{};
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defer attributes.deinit(&o.builder);
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try o.addCommonFnAttributes(&attributes, zcu.root_mod);
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try o.addCommonFnAttributes(&attributes, zcu.root_mod, zcu.root_mod.omit_frame_pointer);
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function_index.setLinkage(.internal, &o.builder);
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function_index.setCallConv(.fastcc, &o.builder);
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@ -6709,8 +6720,6 @@ pub const FuncGen = struct {
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const operand_ty = self.typeOf(pl_op.operand);
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const name = self.air.nullTerminatedString(pl_op.payload);
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if (needDbgVarWorkaround(o)) return .none;
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const debug_local_var = try o.builder.debugLocalVar(
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try o.builder.metadataString(name),
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self.file,
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@ -6734,7 +6743,10 @@ pub const FuncGen = struct {
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},
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"",
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);
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} else if (owner_mod.optimize_mode == .Debug) {
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} else if (owner_mod.optimize_mode == .Debug and !self.is_naked) {
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// We avoid taking this path for naked functions because there's no guarantee that such
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// functions even have a valid stack pointer, making the `alloca` + `store` unsafe.
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const alignment = operand_ty.abiAlignment(pt).toLlvm();
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const alloca = try self.buildAlloca(operand.typeOfWip(&self.wip), alignment);
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_ = try self.wip.store(.normal, operand, alloca, alignment);
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@ -8815,7 +8827,6 @@ pub const FuncGen = struct {
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if (self.is_naked) return arg_val;
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const inst_ty = self.typeOfIndex(inst);
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if (needDbgVarWorkaround(o)) return arg_val;
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const name = self.air.instructions.items(.data)[@intFromEnum(inst)].arg.name;
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if (name == .none) return arg_val;
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@ -9676,7 +9687,7 @@ pub const FuncGen = struct {
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var attributes: Builder.FunctionAttributes.Wip = .{};
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defer attributes.deinit(&o.builder);
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try o.addCommonFnAttributes(&attributes, zcu.root_mod);
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try o.addCommonFnAttributes(&attributes, zcu.root_mod, zcu.root_mod.omit_frame_pointer);
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function_index.setLinkage(.internal, &o.builder);
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function_index.setCallConv(.fastcc, &o.builder);
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@ -11820,16 +11831,6 @@ const optional_layout_version = 3;
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const lt_errors_fn_name = "__zig_lt_errors_len";
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/// Without this workaround, LLVM crashes with "unknown codeview register H1"
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/// https://github.com/llvm/llvm-project/issues/56484
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fn needDbgVarWorkaround(o: *Object) bool {
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const target = o.pt.zcu.getTarget();
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if (target.os.tag == .windows and target.cpu.arch == .aarch64) {
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return true;
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}
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return false;
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}
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fn compilerRtIntBits(bits: u16) u16 {
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inline for (.{ 32, 64, 128 }) |b| {
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if (bits <= b) {
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