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-rw-r--r--erts/emulator/beam/big.c56
-rw-r--r--erts/emulator/beam/big.h1
-rw-r--r--erts/emulator/beam/erl_vm.h2
-rw-r--r--erts/emulator/beam/utils.c105
-rw-r--r--erts/emulator/test/float_SUITE.erl101
-rw-r--r--system/doc/reference_manual/expressions.xml14
6 files changed, 251 insertions, 28 deletions
diff --git a/erts/emulator/beam/big.c b/erts/emulator/beam/big.c
index d18de9ae5d..b90ea6b478 100644
--- a/erts/emulator/beam/big.c
+++ b/erts/emulator/beam/big.c
@@ -1584,6 +1584,62 @@ big_to_double(Wterm x, double* resp)
return 0;
}
+/*
+ * Logic has been copied from erl_bif_guard.c and slightly
+ * modified to use a static instead of dynamic heap
+ */
+Eterm
+double_to_big(double x, Eterm *heap)
+{
+ int is_negative;
+ int ds;
+ ErtsDigit* xp;
+ Eterm res;
+ int i;
+ size_t sz;
+ Eterm* hp;
+ double dbase;
+
+ if (x >= 0) {
+ is_negative = 0;
+ } else {
+ is_negative = 1;
+ x = -x;
+ }
+
+ /* Unscale & (calculate exponent) */
+ ds = 0;
+ dbase = ((double) (D_MASK) + 1);
+ while (x >= 1.0) {
+ x /= dbase; /* "shift" right */
+ ds++;
+ }
+ sz = BIG_NEED_SIZE(ds); /* number of words including arity */
+
+ hp = heap;
+ res = make_big(hp);
+ xp = (ErtsDigit*) (hp + 1);
+
+ for (i = ds - 1; i >= 0; i--) {
+ ErtsDigit d;
+
+ x *= dbase; /* "shift" left */
+ d = x; /* trunc */
+ xp[i] = d; /* store digit */
+ x -= d; /* remove integer part */
+ }
+ while ((ds & (BIG_DIGITS_PER_WORD - 1)) != 0) {
+ xp[ds++] = 0;
+ }
+
+ if (is_negative) {
+ *hp = make_neg_bignum_header(sz-1);
+ } else {
+ *hp = make_pos_bignum_header(sz-1);
+ }
+ return res;
+}
+
/*
** Estimate the number of decimal digits (include sign)
diff --git a/erts/emulator/beam/big.h b/erts/emulator/beam/big.h
index 2afc37004f..256f1c2b45 100644
--- a/erts/emulator/beam/big.h
+++ b/erts/emulator/beam/big.h
@@ -140,6 +140,7 @@ Eterm big_lshift(Eterm, Sint, Eterm*);
int big_comp (Wterm, Wterm);
int big_ucomp (Eterm, Eterm);
int big_to_double(Wterm x, double* resp);
+Eterm double_to_big(double, Eterm*);
Eterm small_to_big(Sint, Eterm*);
Eterm uint_to_big(Uint, Eterm*);
Eterm uword_to_big(UWord, Eterm*);
diff --git a/erts/emulator/beam/erl_vm.h b/erts/emulator/beam/erl_vm.h
index e7fd144ec3..f810392e60 100644
--- a/erts/emulator/beam/erl_vm.h
+++ b/erts/emulator/beam/erl_vm.h
@@ -55,7 +55,7 @@
heap data on the C stack or if we use the buffers in the scheduler data. */
#define TMP_HEAP_SIZE 128 /* Number of Eterm in the schedulers
small heap for transient heap data */
-#define CMP_TMP_HEAP_SIZE 2 /* cmp wants its own tmp-heap... */
+#define CMP_TMP_HEAP_SIZE 32 /* cmp wants its own tmp-heap... */
#define ERL_ARITH_TMP_HEAP_SIZE 4 /* as does erl_arith... */
#define BEAM_EMU_TMP_HEAP_SIZE 2 /* and beam_emu... */
diff --git a/erts/emulator/beam/utils.c b/erts/emulator/beam/utils.c
index 3f6accba2d..825cb140b2 100644
--- a/erts/emulator/beam/utils.c
+++ b/erts/emulator/beam/utils.c
@@ -2642,7 +2642,7 @@ tailrecur_ne:
FloatDef f1, f2;
Eterm big;
#if HEAP_ON_C_STACK
- Eterm big_buf[2]; /* If HEAP_ON_C_STACK */
+ Eterm big_buf[32]; /* If HEAP_ON_C_STACK */
#else
Eterm *big_buf = erts_get_scheduler_data()->cmp_tmp_heap;
#endif
@@ -2653,41 +2653,108 @@ tailrecur_ne:
Eterm aw = a;
Eterm bw = b;
#endif
+#define MAX_LOSSLESS_FLOAT ((double)((1LL << 53) - 2))
+#define MIN_LOSSLESS_FLOAT ((double)(((1LL << 53) - 2)*-1))
b_tag = tag_val_def(bw);
switch(_NUMBER_CODE(a_tag, b_tag)) {
case SMALL_BIG:
- big = small_to_big(signed_val(a), big_buf);
- j = big_comp(big, bw);
+ j = big_sign(bw) ? 1 : -1;
+ break;
+ case BIG_SMALL:
+ j = big_sign(aw) ? -1 : 1;
break;
case SMALL_FLOAT:
- f1.fd = signed_val(a);
GET_DOUBLE(bw, f2);
- j = float_comp(f1.fd, f2.fd);
- break;
- case BIG_SMALL:
- big = small_to_big(signed_val(b), big_buf);
- j = big_comp(aw, big);
+ if (f2.fd < MAX_LOSSLESS_FLOAT && f2.fd > MIN_LOSSLESS_FLOAT) {
+ // Float is within the no loss limit
+ f1.fd = signed_val(aw);
+ j = float_comp(f1.fd, f2.fd);
+#if ERTS_SIZEOF_ETERM == 8
+ } else if (f2.fd > (double) (MAX_SMALL + 1)) {
+ // Float is a positive bignum, i.e. bigger
+ j = -1;
+ } else if (f2.fd < (double) (MIN_SMALL - 1)) {
+ // Float is a negative bignum, i.e. smaller
+ j = 1;
+ } else { // Float is a Sint but less precise
+ j = signed_val(aw) - (Sint) f2.fd;
+ }
+#else
+ } else {
+ // If float is positive it is bigger than small
+ j = (f2.fd > 0.0) ? -1 : 1;
+ }
+#endif // ERTS_SIZEOF_ETERM == 8
break;
case BIG_FLOAT:
- if (big_to_double(aw, &f1.fd) < 0) {
- j = big_sign(a) ? -1 : 1;
+ GET_DOUBLE(bw, f2);
+ if ((f2.fd < (double) (MAX_SMALL + 1))
+ && (f2.fd > (double) (MIN_SMALL - 1))) {
+ // Float is a Sint
+ j = big_sign(aw) ? -1 : 1;
+ } else if ((pow(2.0,(big_arity(aw)-1.0)*D_EXP)-1.0) > fabs(f2.fd)) {
+ // If bignum size shows that it is bigger than the abs float
+ j = big_sign(aw) ? -1 : 1;
+ } else if ((pow(2.0,(big_arity(aw))*D_EXP)-1.0) < fabs(f2.fd)) {
+ // If bignum size shows that it is smaller than the abs float
+ j = f2.fd < 0 ? 1 : -1;
+ } else if (f2.fd < MAX_LOSSLESS_FLOAT && f2.fd > MIN_LOSSLESS_FLOAT) {
+ // Float is within the no loss limit
+ if (big_to_double(aw, &f1.fd) < 0) {
+ j = big_sign(aw) ? -1 : 1;
+ } else {
+ j = float_comp(f1.fd, f2.fd);
+ }
} else {
- GET_DOUBLE(bw, f2);
- j = float_comp(f1.fd, f2.fd);
+ big = double_to_big(f2.fd, big_buf);
+ j = big_comp(aw, big);
}
break;
case FLOAT_SMALL:
GET_DOUBLE(aw, f1);
- f2.fd = signed_val(b);
- j = float_comp(f1.fd, f2.fd);
+ if (f1.fd < MAX_LOSSLESS_FLOAT && f1.fd > MIN_LOSSLESS_FLOAT) {
+ // Float is within the no loss limit
+ f2.fd = signed_val(bw);
+ j = float_comp(f1.fd, f2.fd);
+#if ERTS_SIZEOF_ETERM == 8
+ } else if (f1.fd > (double) (MAX_SMALL + 1)) {
+ // Float is a positive bignum, i.e. bigger
+ j = 1;
+ } else if (f1.fd < (double) (MIN_SMALL - 1)) {
+ // Float is a negative bignum, i.e. smaller
+ j = -1;
+ } else { // Float is a Sint but less precise it
+ j = (Sint) f1.fd - signed_val(bw);
+ }
+#else
+ } else {
+ // If float is positive it is bigger than small
+ j = (f1.fd > 0.0) ? 1 : -1;
+ }
+#endif // ERTS_SIZEOF_ETERM == 8
break;
case FLOAT_BIG:
- if (big_to_double(bw, &f2.fd) < 0) {
- j = big_sign(b) ? 1 : -1;
+ GET_DOUBLE(aw, f1);
+ if ((f1.fd < (double) (MAX_SMALL + 1))
+ && (f1.fd > (double) (MIN_SMALL - 1))) { // Float is a Sint
+ j = big_sign(bw) ? 1 : -1;
+ } else if ((pow(2.0, (big_arity(bw) - 1.0) * D_EXP) - 1.0) > fabs(f1.fd)) {
+ // If bignum size shows that it is bigger than the abs float
+ j = big_sign(bw) ? 1 : -1;
+ } else if ((pow(2.0,(big_arity(bw))*D_EXP)-1.0) < fabs(f1.fd)) {
+ // If bignum size shows that it is smaller than the abs float
+ j = f1.fd < 0 ? -1 : 1;
+ } else if (f1.fd < MAX_LOSSLESS_FLOAT && f1.fd > MIN_LOSSLESS_FLOAT) {
+ // Float is within the no loss limit
+ if (big_to_double(bw, &f2.fd) < 0) {
+ j = big_sign(bw) ? 1 : -1;
+ } else {
+ j = float_comp(f1.fd, f2.fd);
+ }
} else {
- GET_DOUBLE(aw, f1);
- j = float_comp(f1.fd, f2.fd);
+ big = double_to_big(f1.fd, big_buf);
+ j = big_comp(big, bw);
}
break;
default:
diff --git a/erts/emulator/test/float_SUITE.erl b/erts/emulator/test/float_SUITE.erl
index 736510339f..46466427c5 100644
--- a/erts/emulator/test/float_SUITE.erl
+++ b/erts/emulator/test/float_SUITE.erl
@@ -25,7 +25,7 @@
init_per_group/2,end_per_group/2,
init_per_testcase/2,end_per_testcase/2,
fpe/1,fp_drv/1,fp_drv_thread/1,denormalized/1,match/1,
- bad_float_unpack/1]).
+ bad_float_unpack/1,cmp_zero/1, cmp_integer/1, cmp_bignum/1]).
-export([otp_7178/1]).
@@ -41,10 +41,10 @@ suite() -> [{ct_hooks,[ts_install_cth]}].
all() ->
[fpe, fp_drv, fp_drv_thread, otp_7178, denormalized,
- match, bad_float_unpack].
+ match, bad_float_unpack, {group, comparison}].
groups() ->
- [].
+ [{comparison, [parallel], [cmp_zero, cmp_integer, cmp_bignum]}].
init_per_suite(Config) ->
Config.
@@ -187,6 +187,101 @@ bad_float_unpack(Config) when is_list(Config) ->
bad_float_unpack_match(<<F:64/float>>) -> F;
bad_float_unpack_match(<<I:64/integer-signed>>) -> I.
+cmp_zero(_Config) ->
+ cmp(0.5e-323,0).
+
+cmp_integer(_Config) ->
+ Axis = (1 bsl 53)-2.0, %% The point where floating points become unprecise
+ span_cmp(Axis,2,200),
+ cmp(Axis*Axis,round(Axis)).
+
+cmp_bignum(_Config) ->
+ span_cmp((1 bsl 58) - 1.0),%% Smallest bignum float
+
+ %% Test when the big num goes from I to I+1 in size
+ [span_cmp((1 bsl (32*I)) - 1.0) || I <- lists:seq(2,30)],
+
+ %% Test bignum greater then largest float
+ cmp((1 bsl (64*16)) - 1, (1 bsl (64*15)) * 1.0),
+ %% Test when num is much larger then float
+ [cmp((1 bsl (32*I)) - 1, (1 bsl (32*(I-2))) * 1.0) || I <- lists:seq(3,30)],
+ %% Test when float is much larger than num
+ [cmp((1 bsl (64*15)) * 1.0, (1 bsl (32*(I)))) || I <- lists:seq(1,29)],
+
+ %% Test that all int == float works as they should
+ [true = 1 bsl N == (1 bsl N)*1.0 || N <- lists:seq(0, 1023)],
+ [true = (1 bsl N)*-1 == (1 bsl N)*-1.0 || N <- lists:seq(0, 1023)].
+
+span_cmp(Axis) ->
+ span_cmp(Axis, 25).
+span_cmp(Axis, Length) ->
+ span_cmp(Axis, round(Axis) bsr 52, Length).
+span_cmp(Axis, Incr, Length) ->
+ [span_cmp(Axis, Incr, Length, 1 bsl (1 bsl I)) || I <- lists:seq(0,6)].
+%% This function creates tests around number axis. Both <, > and == is tested
+%% for both negative and positive numbers.
+%%
+%% Axis: The number around which to do the tests eg. (1 bsl 58) - 1.0
+%% Incr: How much to increment the test numbers inbetween each test.
+%% Length: Length/2 is the number of Incr away from Axis to test on the
+%% negative and positive plane.
+%% Diff: How much the float and int should differ when comparing
+span_cmp(Axis, Incr, Length, Diff) ->
+ [begin
+ cmp(round(Axis*-1.0)+Diff+I*Incr,Axis*-1.0+I*Incr),
+ cmp(Axis*-1.0+I*Incr,round(Axis*-1.0)-Diff+I*Incr)
+ end || I <- lists:seq((Length div 2)*-1,(Length div 2))],
+ [begin
+ cmp(round(Axis)+Diff+I*Incr,Axis+I*Incr),
+ cmp(Axis+I*Incr,round(Axis)-Diff+I*Incr)
+ end || I <- lists:seq((Length div 2)*-1,(Length div 2))].
+
+cmp(Big,Small) when is_float(Big) ->
+ BigGtSmall = lists:flatten(
+ io_lib:format("~f > ~p",[Big,Small])),
+ BigLtSmall = lists:flatten(
+ io_lib:format("~f < ~p",[Big,Small])),
+ BigEqSmall = lists:flatten(
+ io_lib:format("~f == ~p",[Big,Small])),
+ SmallGtBig = lists:flatten(
+ io_lib:format("~p > ~f",[Small,Big])),
+ SmallLtBig = lists:flatten(
+ io_lib:format("~p < ~f",[Small,Big])),
+ SmallEqBig = lists:flatten(
+ io_lib:format("~p == ~f",[Small,Big])),
+ cmp(Big,Small,BigGtSmall,BigLtSmall,SmallGtBig,SmallLtBig,
+ SmallEqBig,BigEqSmall);
+cmp(Big,Small) when is_float(Small) ->
+ BigGtSmall = lists:flatten(
+ io_lib:format("~p > ~f",[Big,Small])),
+ BigLtSmall = lists:flatten(
+ io_lib:format("~p < ~f",[Big,Small])),
+ BigEqSmall = lists:flatten(
+ io_lib:format("~p == ~f",[Big,Small])),
+ SmallGtBig = lists:flatten(
+ io_lib:format("~f > ~p",[Small,Big])),
+ SmallLtBig = lists:flatten(
+ io_lib:format("~f < ~p",[Small,Big])),
+ SmallEqBig = lists:flatten(
+ io_lib:format("~f == ~p",[Small,Big])),
+ cmp(Big,Small,BigGtSmall,BigLtSmall,SmallGtBig,SmallLtBig,
+ SmallEqBig,BigEqSmall).
+
+cmp(Big,Small,BigGtSmall,BigLtSmall,SmallGtBig,SmallLtBig,
+ SmallEqBig,BigEqSmall) ->
+ {_,_,_,true} = {Big,Small,BigGtSmall,
+ Big > Small},
+ {_,_,_,false} = {Big,Small,BigLtSmall,
+ Big < Small},
+ {_,_,_,false} = {Big,Small,SmallGtBig,
+ Small > Big},
+ {_,_,_,true} = {Big,Small,SmallLtBig,
+ Small < Big},
+ {_,_,_,false} = {Big,Small,SmallEqBig,
+ Small == Big},
+ {_,_,_,false} = {Big,Small,BigEqSmall,
+ Big == Small}.
+
id(I) -> I.
start_node(Config) when is_list(Config) ->
diff --git a/system/doc/reference_manual/expressions.xml b/system/doc/reference_manual/expressions.xml
index 644896cd7f..c24b1110a4 100644
--- a/system/doc/reference_manual/expressions.xml
+++ b/system/doc/reference_manual/expressions.xml
@@ -561,11 +561,15 @@ number &lt; atom &lt; reference &lt; fun &lt; port &lt; pid &lt; tuple &lt; list
<p>Lists are compared element by element. Tuples are ordered by
size, two tuples with the same size are compared element by
element.</p>
- <p>If one of the compared terms is an integer and the other a
- float, the integer is first converted into a float, unless the
- operator is one of =:= and =/=. If the integer is too big to fit
- in a float no conversion is done, but the order is determined by
- inspecting the sign of the numbers.</p>
+ <p>When comparing an integer to a float, the term with the lesser
+ precision will be converted into the other term's type, unless the
+ operator is one of =:= and =/=. A float is more precise than
+ an integer until all significant figures of the float are to the left of
+ the decimal point. This happens when the float is larger/smaller then
+ +/-9007199254740992.0. The conversion strategy is changed
+ depending on the size of the float because otherwise comparison of large
+ floats and integers would loose their transitivity.</p>
+
<p>Returns the Boolean value of the expression, <c>true</c> or
<c>false</c>.</p>
<p>Examples:</p>
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-24 09:04:29 +0000