[Guile-commits] 319/437: Properly handle jit_tramp and function descriptors

[Andy Wingo]

wingo pushed a commit to branch lightning
in repository guile.

commit 0c6f675c8a026826b2482db9f978d422ef1f5328
Author: pcpa <address@hidden>
Date:   Fri Oct 24 14:31:41 2014 -0200

    Properly handle jit_tramp and function descriptors
    
        * lib/jit_ia64.c, lib/jit_ppc.c: Correct handling of function
        descriptor when first prolog is a jit_tramp prolog. The
        test case was using the same jit_context_t, so was not
        triggering this condition.
    
        * lib/jit_ppc-cpu.c: Properly handle jump displacements that
        do not fit on 24 powerpc. This required changing from previous
        "mtlr reg, blr" to "mtctr reg, bctr" to properly handle
        the logic to "hide" function descriptors, but that would
        also be required as the proper jit_jmpr when/if implementing
        optimizations to leaf functions (was working with blr because
        it is saved/reloaded in prolog/epilog).
---
 ChangeLog         | 15 +++++++++++++++
 lib/jit_ia64.c    | 16 ++++++++++++----
 lib/jit_ppc-cpu.c | 57 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
 lib/jit_ppc.c     | 20 +++++++++++++------
 4 files changed, 95 insertions(+), 13 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 85804e6..2558395 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2014-10-24 Paulo Andrade <address@hidden>
+
+       * lib/jit_ia64.c, lib/jit_ppc.c: Correct handling of function
+       descriptor when first prolog is a jit_tramp prolog. The
+       test case was using the same jit_context_t, so was not
+       triggering this condition.
+
+       * lib/jit_ppc-cpu.c: Properly handle jump displacements that
+       do not fit on 24 powerpc. This required changing from previous
+       "mtlr reg, blr" to "mtctr reg, bctr" to properly handle
+       the logic to "hide" function descriptors, but that would
+       also be required as the proper jit_jmpr when/if implementing
+       optimizations to leaf functions (was working with blr because
+       it is saved/reloaded in prolog/epilog).
+
 2014-10-21 Paulo Andrade <address@hidden>
 
        * include/lightning.h, lib/lightning.c: Add three predicates
diff --git a/lib/jit_ia64.c b/lib/jit_ia64.c
index f35f396..e3c6554 100644
--- a/lib/jit_ia64.c
+++ b/lib/jit_ia64.c
@@ -762,10 +762,18 @@ _emit_code(jit_state_t *_jit)
     undo.patch_offset = 0;
 
     undo.prolog_offset = 0;
-    /* code may start with a jump so add an initial function descriptor */
-    word = _jit->pc.w + 16;
-    il(word);                  /* addr */
-    il(0);                     /* gp */
+    for (node = _jitc->head; node; node = node->next)
+       if (node->code != jit_code_label &&
+           node->code != jit_code_note &&
+           node->code != jit_code_name)
+           break;
+    if (node && (node->code != jit_code_prolog ||
+                !(_jitc->functions.ptr + node->w.w)->assume_frame)) {
+       /* code may start with a jump so add an initial function descriptor */
+       word = _jit->pc.w + 16;
+       il(word);               /* addr */
+       il(0);                  /* gp */
+    }
 #define case_rr(name, type)                                            \
            case jit_code_##name##r##type:                              \
                name##r##type(rn(node->u.w), rn(node->v.w));            \
diff --git a/lib/jit_ppc-cpu.c b/lib/jit_ppc-cpu.c
index 2f65d36..18f4096 100644
--- a/lib/jit_ppc-cpu.c
+++ b/lib/jit_ppc-cpu.c
@@ -2985,8 +2985,13 @@ _stxi_l(jit_state_t *_jit, jit_word_t i0, jit_int32_t 
r0, jit_int32_t r1)
 static void
 _jmpr(jit_state_t *_jit, jit_int32_t r0)
 {
+#if 0
     MTLR(r0);
     BLR();
+#else
+    MTCTR(r0);
+    BCTR();
+#endif
 }
 
 /* pc relative jump */
@@ -2995,11 +3000,16 @@ _jmpi(jit_state_t *_jit, jit_word_t i0)
 {
     jit_int32_t                reg;
     jit_word_t         w, d;
-    reg = jit_get_reg(jit_class_gpr|jit_class_nospill);
     w = _jit->pc.w;
     d = (i0 - w) & ~3;
-    B(d);
-    jit_unget_reg(reg);
+    if (can_sign_extend_jump_p(d))
+       B(d);
+    else {
+       reg = jit_get_reg(jit_class_gpr|jit_class_nospill);
+       w = movi_p(rn(reg), i0);
+       jmpr(rn(reg));
+       jit_unget_reg(reg);
+    }
     return (w);
 }
 
@@ -3238,6 +3248,47 @@ _patch_at(jit_state_t *_jit, jit_word_t instr, 
jit_word_t label)
            break;
        case 15:                                        /* LI */
 #if __WORDSIZE == 32
+#  define MTCTR_OFF            2
+#  define BCTR_OFF             3
+#else
+#  define MTCTR_OFF            6
+#  define BCTR_OFF             7
+#endif
+           /* movi reg label; jmpr reg */
+           if (_jitc->jump &&
+#if 0
+               /* check for MLTR(reg) */
+               (u.i[MTCTR_OFF] >> 26) == 31 &&
+               ((u.i[MTCTR_OFF] >> 16) & 0x3ff) == 8 &&
+               ((u.i[MTCTR_OFF] >> 1) & 0x3ff) == 467 &&
+               /* check for BLR */
+               u.i[BCTR_OFF] == 0x4e800020) {
+#else
+               /* check for MTCTR(reg) */
+               (u.i[MTCTR_OFF] >> 26) == 31 &&
+               ((u.i[MTCTR_OFF] >> 16) & 0x3ff) == 9 &&
+               ((u.i[MTCTR_OFF] >> 1) & 0x3ff) == 467 &&
+               /* check for BCTR */
+               u.i[BCTR_OFF] == 0x4e800420) {
+#endif
+               /* zero is used for toc and env, so, quick check
+                * if this is a "jmpi main" like initial jit
+                * instruction */
+               if (((long *)label)[1] == 0 && ((long *)label)[2] == 0) {
+                   for (d = 0; d < _jitc->prolog.offset; d++) {
+                       /* not so pretty, but hides powerpc
+                        * specific abi intrinsics and/or
+                        * implementation from user */
+                       if (_jitc->prolog.ptr[d] == label) {
+                           label += sizeof(void*) * 3;
+                           break;
+                       }
+                   }
+               }
+           }
+#undef BCTR_OFF
+#undef MTCTR_OFF
+#if __WORDSIZE == 32
            assert(!(u.i[0] & 0x1f0000));
            u.i[0] = (u.i[0] & ~0xffff) | ((label >> 16) & 0xffff);
            assert((u.i[1] & 0xfc000000) >> 26 == 24);  /* ORI */
diff --git a/lib/jit_ppc.c b/lib/jit_ppc.c
index cbc5dda..8ef6119 100644
--- a/lib/jit_ppc.c
+++ b/lib/jit_ppc.c
@@ -778,11 +778,19 @@ _emit_code(jit_state_t *_jit)
 
 #if __powerpc__
     undo.prolog_offset = 0;
-    /* code may start with a jump so add an initial function descriptor */
-    word = _jit->pc.w + sizeof(void*) * 3;
-    iw(word);                          /* addr */
-    iw(0);                             /* toc */
-    iw(0);                             /* env */
+    for (node = _jitc->head; node; node = node->next)
+       if (node->code != jit_code_label &&
+           node->code != jit_code_note &&
+           node->code != jit_code_name)
+           break;
+    if (node && (node->code != jit_code_prolog ||
+                !(_jitc->functions.ptr + node->w.w)->assume_frame)) {
+       /* code may start with a jump so add an initial function descriptor */
+       word = _jit->pc.w + sizeof(void*) * 3;
+       iw(word);                       /* addr */
+       iw(0);                          /* toc */
+       iw(0);                          /* env */
+    }
 #endif
 
 #define case_rr(name, type)                                            \
@@ -1262,7 +1270,7 @@ _emit_code(jit_state_t *_jit)
                    }
                }
                else
-                   jmpi(node->u.w);
+                   (void)jmpi_p(node->u.w);
                break;
            case jit_code_callr:
                callr(rn(node->u.w));