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10d514ee58
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 :)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@92415 91177308-0d34-0410-b5e6-96231b3b80d8
48 lines
1.2 KiB
LLVM
48 lines
1.2 KiB
LLVM
; RUN: opt < %s -instcombine -S | FileCheck %s
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@G16 = internal constant [10 x i16] [i16 35, i16 82, i16 69, i16 81, i16 85,
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i16 73, i16 82, i16 69, i16 68, i16 0]
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@GD = internal constant [3 x double] [double 1.0, double 4.0, double -20.0]
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define i1 @test1(i32 %X) {
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%P = getelementptr [10 x i16]* @G16, i32 0, i32 %X
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%Q = load i16* %P
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%R = icmp eq i16 %Q, 0
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ret i1 %R
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; CHECK: @test1
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; CHECK-NEXT: %R = icmp eq i32 %X, 9
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; CHECK-NEXT: ret i1 %R
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}
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define i1 @test2(i32 %X) {
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%P = getelementptr [10 x i16]* @G16, i32 0, i32 %X
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%Q = load i16* %P
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%R = icmp slt i16 %Q, 85
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ret i1 %R
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; CHECK: @test2
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; CHECK-NEXT: %R = icmp ne i32 %X, 4
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; CHECK-NEXT: ret i1 %R
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}
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define i1 @test3(i32 %X) {
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%P = getelementptr [3 x double]* @GD, i32 0, i32 %X
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%Q = load double* %P
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%R = fcmp oeq double %Q, 1.0
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ret i1 %R
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; CHECK: @test3
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; CHECK-NEXT: %R = icmp eq i32 %X, 0
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; CHECK-NEXT: ret i1 %R
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}
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define i1 @test4(i32 %X) {
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%P = getelementptr [10 x i16]* @G16, i32 0, i32 %X
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%Q = load i16* %P
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%R = icmp sle i16 %Q, 73
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ret i1 %R
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; CHECK: @test4
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; CHECK-NEXT: lshr i32 933, %X
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; CHECK-NEXT: and i32 {{.*}}, 1
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; CHECK-NEXT: %R = icmp ne i32 {{.*}}, 0
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; CHECK-NEXT: ret i1 %R
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}
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