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mirror of https://github.com/RPCS3/llvm-mirror.git synced 2024-11-26 04:32:44 +01:00
llvm-mirror/lib
Chris Lattner 1cdc77b8da enhance the compare/load/index optimization to work on *any* load
from a global with 32/64 elements or less (depending on whether
i64 is native on the target), generating a bitshift idiom to 
determine the result.  For example, on test4 we produce:

define i1 @test4(i32 %X) {
  %1 = lshr i32 933, %X                           ; <i32> [#uses=1]
  %2 = and i32 %1, 1                              ; <i32> [#uses=1]
  %R = icmp ne i32 %2, 0                          ; <i1> [#uses=1]
  ret i1 %R
}

This triggers in a number of interesting cases, for example, here's an
fp case:
@A.3255 = internal constant [4 x double] [double 4.100000e+00, double -3.900000e+00, double -1.000000e+00, double 1.000000e+00], align 32 ; <[4 x double]*> [#uses=7]
...
	   %7 = fcmp olt double %3, 0.000000e+00

In this case we make the slen2_tab global dead, which is nice:
@slen2_tab = internal constant [16 x i32] [i32 0, i32 1, i32 2, i32 3, i32 0, i32 1, i32 2, i32 3, i32 1, i32 2, i32 3, i32 1, i32 2, i32 3, i32 2, i32 3], align 32 ; <[16 x i32]*> [#uses=1]
...
	   %204 = icmp eq i32 %46, 0     

Perl has a bunch of these, also on the 'Perl_regkind' array:
@Perl_yygindex = internal constant [51 x i16] [i16 0, i16 0, i16 0, i16 0, i16 374, i16 351, i16 0, i16 -12, i16 0, i16 946, i16 413, i16 -83, i16 0, i16 0, i16 0, i16 -311, i16 -13, i16 4007, i16 2893, i16 0, i16 0, i16 0, i16 0, i16 0, i16 372, i16 -8, i16 0, i16 0, i16 246, i16 -131, i16 43, i16 86, i16 208, i16 -45, i16 -169, i16 987, i16 0, i16 0, i16 0, i16 0, i16 308, i16 0, i16 -271, i16 0, i16 0, i16 0, i16 0, i16 0, i16 0, i16 0, i16 0], align 32 ; <[51 x i16]*> [#uses=1]
...
  %1364 = icmp eq i16 %1361, 0

186.crafty really likes this on 64-bit machines, because it triggers on a bunch of globals like this:
@white_outpost = internal constant [64 x i8] c"\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\02\02\00\00\00\00\00\04\05\05\04\00\00\00\00\03\06\06\03\00\00\00\00\00\01\01\00\00\00\00\00\00\00\00\00\00\00", align 32 ; <[64 x i8]*> [#uses=2]

However the big winner is 403.gcc, which triggers hundreds of times, eliminating all the accesses to the 57-element arrays 'mode_class', mode_unit_size, mode_bitsize, regclass_map, etc.

go 64-bit machines :)

llvm-svn: 92415
2010-01-02 08:56:52 +00:00
..
Analysis constant fold nasty constant expressions formed by llvm-gcc, 2010-01-02 01:22:23 +00:00
Archive
AsmParser remove some fixme's 2009-12-30 06:00:36 +00:00
Bitcode Remove derelict serialization code. 2009-12-31 23:40:17 +00:00
CodeGen Teach codegen to handle: 2010-01-02 00:00:03 +00:00
CompilerDriver Make Path use StringRef instead of std::string where possible. 2009-12-17 21:02:39 +00:00
ExecutionEngine Remove dead store and simplify code. 2009-12-28 01:53:00 +00:00
Linker rename "elements" of metadata to "operands". "Elements" are 2009-12-31 01:22:29 +00:00
MC Pass StringRef by value. 2009-11-06 10:58:06 +00:00
Support Document the edit-distance algorithm used in StringRef, switch it over 2009-12-31 04:24:34 +00:00
System Alternative fix to make sure that the extern declarations used by 2009-12-23 19:12:50 +00:00
Target Teach codegen to lower llvm.powi to an efficient (but not optimal) 2010-01-01 03:32:16 +00:00
Transforms enhance the compare/load/index optimization to work on *any* load 2010-01-02 08:56:52 +00:00
VMCore fix refactoro 2009-12-31 08:23:09 +00:00
Makefile