Optimize addition of a small integer to a variable

Introduce a new i_increment/4 to optimize the addition of
a register and a small integer. This instruction saves two
instruction words compared to the standard instructions
(an i_fetch/2 instruction followed by a i_plus/3 instruction)
and will also be slightly faster.

1 files changed, 35 insertions, 2 deletions

diff --git a/erts/emulator/test/beam_literals_SUITE.erl b/erts/emulator/test/beam_literals_SUITE.erl
index f56d7ac1c5..1eda939cf8 100644
--- a/erts/emulator/test/beam_literals_SUITE.erl
+++ b/erts/emulator/test/beam_literals_SUITE.erl
@@ -23,7 +23,8 @@
 	 matching_bigs/1, matching_more_bigs/1,
 	 matching_bigs_and_smalls/1, badmatch/1, case_clause/1,
 	 receiving/1, literal_type_tests/1,
-	 put_list/1, fconv/1, literal_case_expression/1]).
+	 put_list/1, fconv/1, literal_case_expression/1,
+	 increment/1]).
 
 -include("test_server.hrl").
 
@@ -32,7 +33,7 @@ all(suite) ->
      matching_bigs, matching_more_bigs,
      matching_bigs_and_smalls, badmatch, case_clause,
      receiving, literal_type_tests,
-     put_list, fconv, literal_case_expression].
+     put_list, fconv, literal_case_expression, increment].
 
 putting(doc) -> "Test creating lists and tuples containing big number literals.";
 putting(Config) when is_list(Config) ->
@@ -419,6 +420,38 @@ literal_case_expression(Config) when is_list(Config) ->
     ?line code:purge(Mod),
     ok.
 
+%% Test the i_increment instruction.
+increment(Config) when is_list(Config) ->
+    %% In the 32-bit emulator, Neg32 can be represented as a small,
+    %% but -Neg32 cannot. Therefore the i_increment instruction must
+    %% not be used in the subtraction that follows (since i_increment
+    %% cannot handle a bignum literal).
+    Neg32 = -(1 bsl 27),
+    Big32 = id(1 bsl 32),
+    Result32 = (1 bsl 32) + (1 bsl 27),
+    ?line Result32 = Big32 + (1 bsl 27),
+    ?line Result32 = Big32 - Neg32,
+
+    %% Same thing, but for the 64-bit emulator.
+    Neg64 = -(1 bsl 59),
+    Big64 = id(1 bsl 64),
+    Result64 = (1 bsl 64) + (1 bsl 59),
+    ?line Result64 = Big64 + (1 bsl 59),
+    ?line Result64 = Big64 - Neg64,
+
+    %% Test error handling for the i_increment instruction.
+    Bad = id(bad),
+    ?line {'EXIT',{badarith,_}} = (catch Bad + 42),
+
+    %% Small operands, but a big result.
+    Res32 = 1 bsl 27,
+    Small32 = id(Res32-1),
+    ?line Res32 = Small32 + 1,
+    Res64 = 1 bsl 59,
+    Small64 = id(Res64-1),
+    ?line Res64 = Small64 + 1,
+    ok.
+
 %% Help functions.
 
 chksum(Term) ->