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Commit Graph

9 Commits

Author SHA1 Message Date
Chris Lattner
f44ffcbc2c make these less sensitive to temporary naming.
llvm-svn: 97799
2010-03-05 08:43:33 +00:00
Chris Lattner
3b060b2d41 Truncate GEP indexes larger than the pointer size down to pointer size
when doing this transform if the GEP is not inbounds.  No testcase because
it is very difficult to trigger this: instcombine already canonicalizes
GEP indices to pointer size, so it relies specific permutations of the
instcombine worklist.

Thanks to Duncan for pointing this possible problem out.

llvm-svn: 92495
2010-01-04 18:57:15 +00:00
Chris Lattner
647c629ee4 generalize the previous transformation to handle indexing into
arrays of structs and other arrays, so long as all the subsequent
indexes are constants.  This triggers frequently for stuff like:

@divisions = internal constant [29 x [2 x i32]] [[2 x i32] zeroinitializer, [2 x i32] [i32 0, i32 1], [2 x i32] [i32 0, i32 2], [2 x i32] [i32 0, i32 1], [2 x i32] zeroinitializer, [2 x i32] [i32 0, i32 1], [2 x i32] [i32 0, i32 1], [2 x i32] [i32 0, i32 2], [2 x i32] [i32 0, i32 2], [2 x i32] zeroinitializer, [2 x i32] zeroinitializer, [2 x i32] zeroinitializer, [2 x i32] [i32 0, i32 2], [2 x i32] [i32 0, i32 1], [2 x i32] zeroinitializer, [2 x i32] [i32 1, i32 0], [2 x i32] [i32 1, i32 1], [2 x i32] [i32 1, i32 1], [2 x i32] [i32 1, i32 2], [2 x i32] [i32 1, i32 1], [2 x i32] [i32 1, i32 0], [2 x i32] [i32 1, i32 2], [2 x i32] [i32 1, i32 2], [2 x i32] [i32 1, i32 0], [2 x i32] [i32 1, i32 0], [2 x i32] [i32 1, i32 0], [2 x i32] [i32 1, i32 1], [2 x i32] [i32 1, i32 2], [2 x i32] [i32 1, i32 2]], align 32 ; <[29 x [2 x i32]]*> [#uses=50]

	  %623 = getelementptr inbounds [29 x [2 x i32]]* @divisions, i64 0, i64 %619, i64 0 ; <i32*> [#uses=1]
	   %684 = icmp eq i32 %683, 999 

also for the "my_defs" table in 'gs', etc.

llvm-svn: 92444
2010-01-03 03:03:27 +00:00
Chris Lattner
acb0c133ec teach instcombine to optimize idioms like A[i]&42 == 0. This
occurs in 403.gcc in mode_mask_array, in safe-ctype.c (which
is copied in multiple apps) in _sch_istable, etc.

llvm-svn: 92427
2010-01-02 22:08:28 +00:00
Chris Lattner
4af67af013 Teach the table lookup optimization to generate range compares
when a consequtive sequence of elements all satisfies the 
predicate.  Like the double compare case, this generates better
code than the magic constant case and generalizes to more than
32/64 element array lookups.

Here are some examples where it triggers.  From 403.gcc, most
accesses to the rtx_class array are handled, e.g.:

@rtx_class = constant [153 x i8] c"xxxxxmmmmmmmmxxxxxxxxxxxxmxxxxxxiiixxxxxxxxxxxxxxxxxxxooxooooooxxoooooox3x2c21c2222ccc122222ccccaaaaaa<<<<<<<<<<<<<<<<<<111111111111bbooxxxxxxxxxxcc2211x", align 32 ; <[153 x i8]*> [#uses=547]
   %142 = icmp eq i8 %141, 105
@rtx_class = constant [153 x i8] c"xxxxxmmmmmmmmxxxxxxxxxxxxmxxxxxxiiixxxxxxxxxxxxxxxxxxxooxooooooxxoooooox3x2c21c2222ccc122222ccccaaaaaa<<<<<<<<<<<<<<<<<<111111111111bbooxxxxxxxxxxcc2211x", align 32 ; <[153 x i8]*> [#uses=543]
	   %165 = icmp eq i8 %164, 60      

Also, most of the 59-element arrays (mode_class/rid_to_yy, etc) 
optimized before are actually range compares.  This lets 32-bit
machines optimize them.

400.perlbmk has stuff like this:

400.perlbmk: PL_regkind, even for 32-bit:
@PL_regkind = constant [62 x i8] c"\00\00\02\02\02\06\06\06\06\09\09\0B\0B\0D\0E\0E\0E\11\12\12\14\14\16\16\18\18\1A\1A\1C\1C\1E\1F !!!$$&'((((,-.///88886789:;8$", align 32 ; <[62 x i8]*> [#uses=4]
	   %811 = icmp ne i8 %810, 33 

@PL_utf8skip = constant [256 x i8] c"\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\01\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\02\03\03\03\03\03\03\03\03\03\03\03\03\03\03\03\03\04\04\04\04\04\04\04\04\05\05\05\05\06\06\07\0D", align 32 ; <[256 x i8]*> [#uses=94]
	   %12 = icmp ult i8 %10, 2
           
etc.

llvm-svn: 92426
2010-01-02 21:50:18 +00:00
Chris Lattner
e1a2489017 Generalize the previous xform to handle cases where exactly
two elements match or don't match with two comparisons.  For
example, the testcase compiles into:

define i1 @test5(i32 %X) {
  %1 = icmp eq i32 %X, 2                          ; <i1> [#uses=1]
  %2 = icmp eq i32 %X, 7                          ; <i1> [#uses=1]
  %R = or i1 %1, %2                               ; <i1> [#uses=1]
  ret i1 %R
}

This generalizes the previous xforms when the array is larger than
64 elements (and this case matches) and generates better code for
cases where it overlaps with the magic bitshift case.

This generalizes more cases than you might expect.  For example,
400.perlbmk has:

@PL_utf8skip = constant [256 x i8] c"\01\01\01\...
%15 = icmp ult i8 %7, 7

403.gcc has:
@rid_to_yy = internal constant [114 x i16] [i16 259, i16 260, ...
%18 = icmp eq i16 %16, 295 

and xalancbmk has a bunch of examples, such as 
_ZN11xercesc_2_5L15gCombiningCharsE and _ZN11xercesc_2_5L10gBaseCharsE.

llvm-svn: 92417
2010-01-02 09:35:17 +00:00
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
Chris Lattner
59136ba5ad enhance the previous optimization to work with fcmp in addition
to icmp.

llvm-svn: 92412
2010-01-02 08:20:51 +00:00
Chris Lattner
f3f6c10218 Teach instcombine to fold compares of loads from constant
arrays with variable indices into a comparison of the index
with a constant.  The most common occurrence of this that
I see by far is stuff like:

if ("foobar"[i] == '\0') ...

which we compile into: if (i == 6), saving a load and 
materialization of the global address.  This also exposes 
loop trip count information to later passes in many cases.

This triggers hundreds of times in xalancbmk, which is where I first
noticed it, but it also triggers in many other apps.  Here are a few 
interesting ones from various apps:

@must_be_connected_without = internal constant [8 x i8*] [i8* getelementptr inbounds ([3 x i8]* @.str64320, i64 0, i64 0), i8* getelementptr inbounds ([3 x i8]* @.str27283, i64 0, i64 0), i8* getelementptr inbounds ([4 x i8]* @.str71327, i64 0, i64 0), i8* getelementptr inbounds ([4 x i8]* @.str72328, i64 0, i64 0), i8* getelementptr inbounds ([3 x i8]* @.str18274, i64 0, i64 0), i8* getelementptr inbounds ([6 x i8]* @.str11267, i64 0, i64 0), i8* getelementptr inbounds ([3 x i8]* @.str32288, i64 0, i64 0), i8* null], align 32 ; <[8 x i8*]*> [#uses=2]
  %scevgep.i = getelementptr [8 x i8*]* @must_be_connected_without, i64 0, i64 %indvar.i ; <i8**> [#uses=1]
  %17 = load ...
  %18 = icmp eq i8* %17, null                     ; <i1> [#uses=1]
-> icmp eq i64 %indvar.i, 7 


@yytable1095 = internal constant [84 x i8] c"\12\01(\05\06\07\08\09\0A\0B\0C\0D\0E1\0F\10\11266\1D: \10\11,-,0\03'\10\11B6\04\17&\18\1945\05\06\07\08\09\0A\0B\0C\0D\0E\1E\0F\10\11*\1A\1B\1C$3+>#%;<IJ=ADFEGH9KL\00\00\00C", align 32 ; <[84 x i8]*> [#uses=2]
  %57 = getelementptr inbounds [84 x i8]* @yytable1095, i64 0, i64 %56 ; <i8*> [#uses=1]
   %mode.0.in = getelementptr inbounds [9 x i32]* @mb_mode_table, i64 0, i64 %.pn ; <i32*> [#uses=1]
load ...
   %64 = icmp eq i8 %58, 4                         ; <i1> [#uses=1]
-> icmp eq i64 %.pn, 35             ; <i1> [#uses=0]


@gsm_DLB = internal constant [4 x i16] [i16 6554, i16 16384, i16 26214, i16 32767]
%scevgep.i = getelementptr [4 x i16]* @gsm_DLB, i64 0, i64 %indvar.i ; <i16*> [#uses=1]
%425 = load %scevgep.i
%426 = icmp eq i16 %425, -32768                 ; <i1> [#uses=0]
-> false

llvm-svn: 92411
2010-01-02 08:12:04 +00:00