various relocation related optimization

With 59ca5a8db, querying if a symbol is defined is cheap. If we're
compiling code that calls foo() and we defined foo() in this compilation
unit, we already know its offset within the .text section, so use it
instead of emitting a relocation for the linker to handle.  Also, put
small literal data in the .text section instead of .rodata.  This seems
to improve performance (cache locality?), and as a bonus, it will be
good for aarch64's instr encoding with smallish PC-relative offsets.

1 files changed, 6 insertions, 4 deletions

diff --git a/ir/ir.c b/ir/ir.c
index 3befc18..5bc94aa 100644
--- a/ir/ir.c
+++ b/ir/ir.c
@@ -147,7 +147,8 @@ mksymref(const char *s, bool isfunc)
 union ref
 mkdatref(const char *name, union type ctype, uint siz, uint align, const void *bytes, uint n, bool deref)
 {
-   struct irdat dat = { .ctype = ctype, .align = align, .siz = siz, .name = name, .section = Srodata };
+   struct irdat dat = { .ctype = ctype, .align = align, .siz = siz, .name = name };
+   dat.section = align >= 4 && align <= targ_primsizes[TYPTR] && siz <= 16 ? Stext : Srodata;
 
    assert(n <= siz && siz && align);
    if (!name) {
@@ -155,14 +156,15 @@ mkdatref(const char *name, union type ctype, uint siz, uint align, const void *b
       char buf[32];
       struct wbuf wbuf = MEMBUF(buf, sizeof buf);
 
-      bfmt(&wbuf, ".L.%d", dattab.n);
+      bfmt(&wbuf, ".L%c.%d", dat.section == Stext ? 'L' : 'D', dattab.n);
       ioputc(&wbuf, 0);
       assert(!wbuf.err);
       dat.name = name = intern(buf);
    }
    dat.off = objnewdat(name, dat.section, 0, siz, align);
-   memcpy(objout.rodata.p+dat.off, bytes, n);
-   memset(objout.rodata.p+dat.off+n, 0, siz - n);
+   uchar *p = (dat.section == Stext ? objout.textbegin : objout.rodata.p) + dat.off;
+   if (n) memcpy(p, bytes, n);
+   if (dat.section != Stext) memset(p+n, 0, siz - n);
    vpush(&dattab, dat);
    return mkref(RXCON, addcon(&(struct xcon){.isdat = 1, .deref = deref, .dat = dattab.n - 1}));
 }