Merge branch 'lukas/erts/large_float_cmp/OTP-9497'

* lukas/erts/large_float_cmp/OTP-9497:
  Update documentation after changes in integer and float comparison
  Do small optimisation on platforms with 32 bit Eterm
  Add tests for equality checking
  Optimize comparison of huge floats and smaller bignums
  Add tests for comparing large floats and small bignums
  Cleanup double_to_bignum conversion code
  Update size of tmp cmp bignum buffer
  Expand tests for float and number comparison
  Update heauristic to work on halfword
  Add heauristics bignum vs float checks
  Optimise bugnum and small comparison
  Add float vs integer comparison tests
  Update integer and floating point number comparisons

1 files changed, 98 insertions, 3 deletions

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) ->