File 1261-emulator-Remove-vestiges-of-special-handling-of-x-0.patch of Package erlang
From f53c6f4fc8da66fadd90f6a2d85b317cc52641e8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Gustavsson?= <bjorn@erlang.org>
Date: Sat, 10 Jun 2023 13:21:55 +0200
Subject: [PATCH] emulator: Remove vestiges of special handling of x(0)
In the BEAM emulator, X register 0 (`x(0)`) used to be specially
handled by the macro `r(0)` so that it could be placed in a CPU
register.
That made sense for platforms with many registers such as Sparc and
PowerPC. For the register-starved x86_64 platform it is not possible
to allocate a CPU register for `x(0)`. Therefore, in
1f996cc46a8c93 (part of Erlang/OTP 19), the special handling of `x(0)`
was removed. Removing that special case simplified the code in many
places.
Get rid of the vestiges of the special handling of `x(0)`. While at
it, also re-introduce the `REG_xregs` attribute for the variable
holding the pointer to the X registers.
---
erts/emulator/beam/beam_common.h | 1 -
erts/emulator/beam/emu/beam_emu.c | 8 ++++----
erts/emulator/beam/emu/bif_instrs.tab | 22 +++++++++++-----------
erts/emulator/beam/emu/bs_instrs.tab | 2 +-
erts/emulator/beam/emu/instrs.tab | 16 ++++++++--------
erts/emulator/beam/emu/msg_instrs.tab | 2 +-
erts/emulator/beam/emu/trace_instrs.tab | 6 +++---
erts/emulator/utils/beam_makeops | 2 +-
8 files changed, 29 insertions(+), 30 deletions(-)
diff --git a/erts/emulator/beam/beam_common.h b/erts/emulator/beam/beam_common.h
index ee7a41c9b8..3c93d580a6 100644
--- a/erts/emulator/beam/beam_common.h
+++ b/erts/emulator/beam/beam_common.h
@@ -111,7 +111,6 @@ do { \
#define x(N) reg[N]
#define y(N) E[N]
-#define r(N) x(N)
#define Q(N) (N*sizeof(Eterm *))
#define l(N) (freg[N].fd)
diff --git a/erts/emulator/beam/emu/beam_emu.c b/erts/emulator/beam/emu/beam_emu.c
index 0c91c1ec83..c2081ab3d0 100644
--- a/erts/emulator/beam/emu/beam_emu.c
+++ b/erts/emulator/beam/emu/beam_emu.c
@@ -266,10 +266,10 @@ void process_main(ErtsSchedulerData *esdp)
ERTS_DECLARE_DUMMY(Eterm pid);
#endif
- /* Pointer to X registers: x(1)..x(N); reg[0] is used when doing GC,
- * in all other cases x0 is used.
+ /*
+ * Pointer to X registers: x(0)..x(N).
*/
- register Eterm* reg = NULL;
+ register Eterm* reg REG_xregs = NULL;
/*
* Top of heap (next free location); grows upwards.
@@ -552,7 +552,7 @@ void process_main(ErtsSchedulerData *esdp)
if (I == 0) {
goto do_schedule;
} else {
- ASSERT(!is_value(r(0)));
+ ASSERT(!is_value(x(0)));
SWAPIN;
Goto(*I);
}
diff --git a/erts/emulator/beam/emu/bif_instrs.tab b/erts/emulator/beam/emu/bif_instrs.tab
index d1ec68168a..ef26fd4756 100644
--- a/erts/emulator/beam/emu/bif_instrs.tab
+++ b/erts/emulator/beam/emu/bif_instrs.tab
@@ -281,8 +281,8 @@ call_light_bif(Bif, Exp) {
}
ERTS_MSACC_SET_STATE_CACHED_M_X(ERTS_MSACC_STATE_EMULATOR);
if (ERTS_LIKELY(is_value(result))) {
- r(0) = result;
- CHECK_TERM(r(0));
+ x(0) = result;
+ CHECK_TERM(x(0));
$NEXT0();
} else if (c_p->freason == TRAP) {
/*
@@ -385,8 +385,8 @@ call_light_bif_only(Bif, Exp) {
/*
* Success. Store the result and return to the caller.
*/
- r(0) = result;
- CHECK_TERM(r(0));
+ x(0) = result;
+ CHECK_TERM(x(0));
$return();
} else if (c_p->freason == TRAP) {
/*
@@ -426,15 +426,15 @@ send() {
PRE_BIF_SWAPOUT(c_p);
c_p->fcalls = FCALLS - 1;
- result = erl_send(c_p, r(0), x(1));
+ result = erl_send(c_p, x(0), x(1));
ERTS_VERIFY_UNUSED_TEMP_ALLOC(c_p);
ERTS_REQ_PROC_MAIN_LOCK(c_p);
PROCESS_MAIN_CHK_LOCKS(c_p);
HTOP = HEAP_TOP(c_p);
FCALLS = c_p->fcalls;
if (ERTS_LIKELY(is_value(result))) {
- r(0) = result;
- CHECK_TERM(r(0));
+ x(0) = result;
+ CHECK_TERM(x(0));
} else if (c_p->freason == TRAP) {
$SAVE_CONTINUATION_POINTER($NEXT_INSTRUCTION);
SET_I(c_p->i);
@@ -605,8 +605,8 @@ nif_bif.epilogue() {
FCALLS = c_p->fcalls;
ERTS_DBG_CHK_REDS(c_p, FCALLS);
if (ERTS_LIKELY(is_value(nif_bif_result))) {
- r(0) = nif_bif_result;
- CHECK_TERM(r(0));
+ x(0) = nif_bif_result;
+ CHECK_TERM(x(0));
$RETURN();
Goto(*I);
} else if (c_p->freason == TRAP) {
@@ -632,13 +632,13 @@ i_load_nif() {
Eterm result;
PRE_BIF_SWAPOUT(c_p);
- result = erts_load_nif(c_p, I, r(0), r(1));
+ result = erts_load_nif(c_p, I, x(0), x(1));
erts_release_code_mod_permission();
ERTS_REQ_PROC_MAIN_LOCK(c_p);
SWAPIN;
if (ERTS_LIKELY(is_value(result))) {
- r(0) = result;
+ x(0) = result;
$NEXT0();
} else {
static ErtsCodeMFA mfa = {am_erlang, am_load_nif, 2};
diff --git a/erts/emulator/beam/emu/bs_instrs.tab b/erts/emulator/beam/emu/bs_instrs.tab
index a42c2eb331..9a1360c26e 100644
--- a/erts/emulator/beam/emu/bs_instrs.tab
+++ b/erts/emulator/beam/emu/bs_instrs.tab
@@ -738,7 +738,7 @@ i_bs_private_append(Fail, Unit, Size, Src, Dst) {
bs_init_writable() {
HEAVY_SWAPOUT;
- r(0) = erts_bs_init_writable(c_p, r(0));
+ x(0) = erts_bs_init_writable(c_p, x(0));
HEAVY_SWAPIN;
}
diff --git a/erts/emulator/beam/emu/instrs.tab b/erts/emulator/beam/emu/instrs.tab
index 88e6da9bf1..e675eadf99 100644
--- a/erts/emulator/beam/emu/instrs.tab
+++ b/erts/emulator/beam/emu/instrs.tab
@@ -311,7 +311,7 @@ apply_last(Arity, Deallocate) {
APPLY_FUN(Next) {
HEAVY_SWAPOUT;
- $Next = apply_fun(c_p, r(0), x(1), reg);
+ $Next = apply_fun(c_p, x(0), x(1), reg);
HEAVY_SWAPIN;
if (ERTS_UNLIKELY(next == NULL)) {
@@ -378,7 +378,7 @@ return() {
//| -no_next
DTRACE_RETURN_FROM_PC(c_p, I);
$RETURN();
- CHECK_TERM(r(0));
+ CHECK_TERM(x(0));
HEAP_SPACE_VERIFIED(0);
$DISPATCH_RETURN();
@@ -1129,11 +1129,11 @@ catch_end(Y) {
* x3 = Exception class
*/
$try_end($Y);
- if (is_non_value(r(0))) {
+ if (is_non_value(x(0))) {
ASSERT(c_p->fvalue == NIL);
ASSERT(c_p->ftrace == NIL);
if (x(3) == am_throw) {
- r(0) = x(1);
+ x(0) = x(1);
} else {
if (x(3) == am_error) {
SWAPOUT;
@@ -1150,11 +1150,11 @@ catch_end(Y) {
SWAPIN;
$MAYBE_EXIT_AFTER_GC();
}
- r(0) = TUPLE2(HTOP, am_EXIT, x(1));
+ x(0) = TUPLE2(HTOP, am_EXIT, x(1));
HTOP += 3;
}
}
- CHECK_TERM(r(0));
+ CHECK_TERM(x(0));
}
try_end(Y) {
@@ -1164,10 +1164,10 @@ try_end(Y) {
try_case(Y) {
$try_end($Y);
- ASSERT(is_non_value(r(0)));
+ ASSERT(is_non_value(x(0)));
ASSERT(c_p->fvalue == NIL);
ASSERT(c_p->ftrace == NIL);
- r(0) = x(3);
+ x(0) = x(3);
}
try_case_end(Src) {
diff --git a/erts/emulator/beam/emu/msg_instrs.tab b/erts/emulator/beam/emu/msg_instrs.tab
index ef733ae80a..00c7291257 100644
--- a/erts/emulator/beam/emu/msg_instrs.tab
+++ b/erts/emulator/beam/emu/msg_instrs.tab
@@ -136,7 +136,7 @@ i_loop_rec(Dest) {
ASSERT(msgp == erts_msgq_peek_msg(c_p));
ASSERT(ERTS_SIG_IS_INTERNAL_MSG(msgp));
- r(0) = ERL_MESSAGE_TERM(msgp);
+ x(0) = ERL_MESSAGE_TERM(msgp);
}
remove_message() {
diff --git a/erts/emulator/beam/emu/trace_instrs.tab b/erts/emulator/beam/emu/trace_instrs.tab
index 9b0b377ed7..14ac98a311 100644
--- a/erts/emulator/beam/emu/trace_instrs.tab
+++ b/erts/emulator/beam/emu/trace_instrs.tab
@@ -24,7 +24,7 @@ return_trace() {
SWAPOUT; /* Needed for shared heap */
ERTS_UNREQ_PROC_MAIN_LOCK(c_p);
- erts_trace_return(c_p, mfa, r(0), ERTS_TRACER_FROM_ETERM(E+2)/* tracer */);
+ erts_trace_return(c_p, mfa, x(0), ERTS_TRACER_FROM_ETERM(E+2)/* tracer */);
ERTS_REQ_PROC_MAIN_LOCK(c_p);
SWAPIN;
E += 1 + BEAM_RETURN_TRACE_FRAME_SZ;
@@ -135,10 +135,10 @@ i_perf_counter() {
ts = erts_sys_perf_counter();
if (IS_SSMALL(ts)) {
- r(0) = make_small((Sint)ts);
+ x(0) = make_small((Sint)ts);
} else {
$GC_TEST(0, ERTS_SINT64_HEAP_SIZE(ts), 0);
- r(0) = make_big(HTOP);
+ x(0) = make_big(HTOP);
#if defined(ARCH_32)
if (ts >= (((Uint64) 1) << 32)) {
*HTOP = make_pos_bignum_header(2);
diff --git a/erts/emulator/utils/beam_makeops b/erts/emulator/utils/beam_makeops
index 796fff7182..a3d18bfbe0 100755
--- a/erts/emulator/utils/beam_makeops
+++ b/erts/emulator/utils/beam_makeops
@@ -1728,7 +1728,7 @@ sub code_gen {
last SWITCH;
};
/r/ and do {
- push(@f, "r(0)");
+ push(@f, "x(0)");
last SWITCH;
};
/[lxyS]/ and do {
--
2.35.3
