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Age	Commit message (Collapse)	Author
2018-06-18	Update copyright year	Henrik Nord

2017-09-28	Eliminate MY_IS_SSMALL()	Björn Gustavsson
	For a long time, there has been the two macros IS_SSMALL() and MY_IS_SSMALL() that do exactly the same thing. There should only be one, and it should be called IS_SSMALL(). However, we must decide which implementation to use. When MY_IS_SSMALL() was introduced a long time ago, it was the most efficient. In a modern C compiler, there might not be any difference. To find out, I used the following small C program to examine the code generation: #include <stdio.h> typedef unsigned int Uint32; typedef unsigned long Uint64; typedef long Sint; #define SWORD_CONSTANT(Const) Const##L #define SMALL_BITS (64-4) #define MAX_SMALL ((SWORD_CONSTANT(1) << (SMALL_BITS-1))-1) #define MIN_SMALL (-(SWORD_CONSTANT(1) << (SMALL_BITS-1))) #define MY_IS_SSMALL32(x) (((Uint32) ((((x)) >> (SMALL_BITS-1)) + 1)) < 2) #define MY_IS_SSMALL64(x) (((Uint64) ((((x)) >> (SMALL_BITS-1)) + 1)) < 2) #define MY_IS_SSMALL(x) (sizeof(x) == sizeof(Uint32) ? MY_IS_SSMALL32(x) : MY_IS_SSMALL64(x)) #define IS_SSMALL(x) (((x) >= MIN_SMALL) && ((x) <= MAX_SMALL)) void original(Sint n) { if (IS_SSMALL(n)) { printf("yes\n"); } } void enhanced(Sint n) { if (MY_IS_SSMALL(n)) { printf("yes\n"); } } gcc 7.2 produced the following code for the original() function: .LC0: .string "yes" original(long): movabs rax, 576460752303423488 add rdi, rax movabs rax, 1152921504606846975 cmp rdi, rax jbe .L4 rep ret .L4: mov edi, OFFSET FLAT:.LC0 jmp puts clang 5.0.0 produced the following code which is slightly better: original(long): movabs rax, 576460752303423488 add rax, rdi shr rax, 60 jne .LBB0_1 mov edi, .Lstr jmp puts # TAILCALL .LBB0_1: ret .Lstr: .asciz "yes" However, in the context of beam_emu.c, clang could produce similar to what gcc produced. gcc 7.2 produced the following code when MY_IS_SSMALL() was used: .LC0: .string "yes" enhanced(long): sar rdi, 59 add rdi, 1 cmp rdi, 1 jbe .L4 rep ret .L4: mov edi, OFFSET FLAT:.LC0 jmp puts clang produced similar code. This code seems to be the cheapest. There are four instructions, and there is no loading of huge integer constants.
2017-08-11	Make '0 bsl BigNumber' consistently succeed	Björn Gustavsson
	'0 bsl 134217728' would fail with a system limit exception on a 32-bit BEAM machine, but not on a 64-bit BEAM machine. Smaller values on the right would always work. Make erlang:bsl(0, BigNumber) always return 0 to make for consistency. (The previous commit accidentally did that change for '0 bsl BigNumber'.)
2016-03-15	update copyright-year	Henrik Nord

2015-07-01	erts: Remove halfword !HEAP_ON_C_STACK	Björn-Egil Dahlberg

2015-06-18	Change license text to APLv2	Bruce Yinhe

2015-05-06	erts: Don't let the compiler optimize pos. zero fix	Björn-Egil Dahlberg

2011-10-26	Use the proper macros in all BIFs	Björn Gustavsson
	As a preparation for changing the calling convention for BIFs, make sure that all BIFs use the macros. Also, eliminate all calls from one BIF to another, since that also breaks the calling convention abstraction.
2010-03-10	Fit all heap data into the 32-bit address range	Patrik Nyblom
	This is the first step in the implementation of the half-word emulator, a 64-bit emulator where all pointers to heap data will be stored in 32-bit words. Code specific for this emulator variant is conditionally compiled when the HALFWORD_HEAP define has a non-zero value. First force all pointers to heap data to fall into a single 32-bit range, but still store them in 64-bit words. Temporary term data stored on C stack is moved into scheduler specific storage (allocated as heaps) and macros are added to make this happen only in emulators where this is needed. For a vanilla VM the temporary terms are still stored on the C stack.
2010-01-13	OTP-8240 Improved GC performance after BIF/NIF call when a lot of heap	Sverker Eriksson
	fragments was created. This will mainly benefit NIFs that return large compound terms.
2009-11-20	The R13B03 release.OTP_R13B03	Erlang/OTP