CBE: support call attributes

 * Support always_tail and never_tail/never_inline with a comptime callee using clang
 * Support never_inline using gcc
 * Support never_inline using msvc

Unfortunately, can't enable behavior tests because of the conditional support.

1 files changed, 14 insertions, 21 deletions

diff --git a/src/link/C.zig b/src/link/C.zig
index 262e4e4923..5663ba71e2 100644
--- a/src/link/C.zig
+++ b/src/link/C.zig
@@ -247,8 +247,8 @@ pub fn flushModule(self: *C, comp: *Compilation, prog_node: *std.Progress.Node)
 
     const abi_define = abiDefine(comp);
 
-    // Covers defines, zig.h, ctypes, asm, lazy fwd, lazy code.
-    try f.all_buffers.ensureUnusedCapacity(gpa, 6);
+    // Covers defines, zig.h, ctypes, asm, lazy fwd.
+    try f.all_buffers.ensureUnusedCapacity(gpa, 5);
 
     if (abi_define) |buf| f.appendBufAssumeCapacity(buf);
     f.appendBufAssumeCapacity(zig_h);
@@ -263,8 +263,8 @@ pub fn flushModule(self: *C, comp: *Compilation, prog_node: *std.Progress.Node)
         f.appendBufAssumeCapacity(asm_buf.items);
     }
 
-    const lazy_indices = f.all_buffers.items.len;
-    f.all_buffers.items.len += 2;
+    const lazy_index = f.all_buffers.items.len;
+    f.all_buffers.items.len += 1;
 
     try self.flushErrDecls(&f.lazy_db);
 
@@ -297,6 +297,7 @@ pub fn flushModule(self: *C, comp: *Compilation, prog_node: *std.Progress.Node)
 
     {
         // We need to flush lazy ctypes after flushing all decls but before flushing any decl ctypes.
+        // This ensures that every lazy CType.Index exactly matches the global CType.Index.
         assert(f.ctypes.count() == 0);
         try self.flushCTypes(&f, .none, f.lazy_db.ctypes);
 
@@ -305,30 +306,22 @@ pub fn flushModule(self: *C, comp: *Compilation, prog_node: *std.Progress.Node)
             try self.flushCTypes(&f, entry.key_ptr.toOptional(), entry.value_ptr.ctypes);
     }
 
-    {
-        f.all_buffers.items[lazy_indices + 0] = .{
-            .iov_base = if (f.lazy_db.fwd_decl.items.len > 0) f.lazy_db.fwd_decl.items.ptr else "",
-            .iov_len = f.lazy_db.fwd_decl.items.len,
-        };
-        f.file_size += f.lazy_db.fwd_decl.items.len;
-
-        f.all_buffers.items[lazy_indices + 1] = .{
-            .iov_base = if (f.lazy_db.code.items.len > 0) f.lazy_db.code.items.ptr else "",
-            .iov_len = f.lazy_db.code.items.len,
-        };
-        f.file_size += f.lazy_db.code.items.len;
-    }
-
     f.all_buffers.items[ctypes_index] = .{
         .iov_base = if (f.ctypes_buf.items.len > 0) f.ctypes_buf.items.ptr else "",
         .iov_len = f.ctypes_buf.items.len,
     };
     f.file_size += f.ctypes_buf.items.len;
 
+    f.all_buffers.items[lazy_index] = .{
+        .iov_base = if (f.lazy_db.fwd_decl.items.len > 0) f.lazy_db.fwd_decl.items.ptr else "",
+        .iov_len = f.lazy_db.fwd_decl.items.len,
+    };
+    f.file_size += f.lazy_db.fwd_decl.items.len;
+
     // Now the code.
-    try f.all_buffers.ensureUnusedCapacity(gpa, decl_values.len);
-    for (decl_values) |decl|
-        f.appendBufAssumeCapacity(decl.code.items);
+    try f.all_buffers.ensureUnusedCapacity(gpa, 1 + decl_values.len);
+    f.appendBufAssumeCapacity(f.lazy_db.code.items);
+    for (decl_values) |decl| f.appendBufAssumeCapacity(decl.code.items);
 
     const file = self.base.file.?;
     try file.setEndPos(f.file_size);