stage2: passing threadlocal tests for x86_64-linux

 * use the real start code for LLVM backend with x86_64-linux
   - there is still a check for zig_backend after initializing the TLS
     area to skip some stuff.
 * introduce new AIR instructions and implement them for the LLVM
   backend. They are the same as `call` except with a modifier.
   - call_always_tail
   - call_never_tail
   - call_never_inline
 * LLVM backend calls hasRuntimeBitsIgnoringComptime in more places to
   avoid unnecessarily depending on comptimeOnly being resolved for some
   types.
 * LLVM backend: remove duplicate code for setting linkage and value
   name. The canonical place for this is in `updateDeclExports`.
 * LLVM backend: do some assembly template massaging to make `%%`
   rendered as `%`. More hacks will be needed to make inline assembly
   catch up with stage1.

1 files changed, 7 insertions, 2 deletions

diff --git a/src/arch/x86_64/CodeGen.zig b/src/arch/x86_64/CodeGen.zig
index 4f8dd0fb0b..be3d09bc8f 100644
--- a/src/arch/x86_64/CodeGen.zig
+++ b/src/arch/x86_64/CodeGen.zig
@@ -670,7 +670,6 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .ret_addr        => try self.airRetAddr(inst),
             .frame_addr      => try self.airFrameAddress(inst),
             .fence           => try self.airFence(),
-            .call            => try self.airCall(inst),
             .cond_br         => try self.airCondBr(inst),
             .dbg_stmt        => try self.airDbgStmt(inst),
             .fptrunc         => try self.airFptrunc(inst),
@@ -719,6 +718,11 @@ fn genBody(self: *Self, body: []const Air.Inst.Index) InnerError!void {
             .prefetch        => try self.airPrefetch(inst),
             .mul_add         => try self.airMulAdd(inst),
 
+            .call              => try self.airCall(inst, .auto),
+            .call_always_tail  => try self.airCall(inst, .always_tail),
+            .call_never_tail   => try self.airCall(inst, .never_tail),
+            .call_never_inline => try self.airCall(inst, .never_inline),
+
             .atomic_store_unordered => try self.airAtomicStore(inst, .Unordered),
             .atomic_store_monotonic => try self.airAtomicStore(inst, .Monotonic),
             .atomic_store_release   => try self.airAtomicStore(inst, .Release),
@@ -3263,7 +3267,8 @@ fn airFence(self: *Self) !void {
     //return self.finishAirBookkeeping();
 }
 
-fn airCall(self: *Self, inst: Air.Inst.Index) !void {
+fn airCall(self: *Self, inst: Air.Inst.Index, modifier: std.builtin.CallOptions.Modifier) !void {
+    if (modifier == .always_tail) return self.fail("TODO implement tail calls for x86_64", .{});
     const pl_op = self.air.instructions.items(.data)[inst].pl_op;
     const callee = pl_op.operand;
     const extra = self.air.extraData(Air.Call, pl_op.payload);