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llvm-project/llvm/test/Transforms/LowerBitSets/layout.ll

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LowerBitSets: Introduce global layout builder. The builder is based on a layout algorithm that tries to keep members of small bit sets together. The new layout compresses Chromium's bit sets to around 15% of their original size. Differential Revision: http://reviews.llvm.org/D7796 llvm-svn: 230394
2015-02-25 07:17:02 +08:00
; RUN: opt -S -lowerbitsets < %s | FileCheck %s
target datalayout = "e-p:32:32"
; Tests that this set of globals is laid out according to our layout algorithm
; (see GlobalLayoutBuilder in include/llvm/Transforms/IPO/LowerBitSets.h).
; The chosen layout in this case is a, e, b, d, c.
LowerBitSets: Align referenced globals. This change aligns globals to the next highest power of 2 bytes, up to a maximum of 128. This makes it more likely that we will be able to compress bit sets with a greater alignment. In many more cases, we can now take advantage of a new optimization also introduced in this patch that removes bit set checks if the bit set is all ones. The 128 byte maximum was found to provide the best tradeoff between instruction overhead and data overhead in a recent build of Chromium. It allows us to remove ~2.4MB of instructions at the cost of ~250KB of data. Differential Revision: http://reviews.llvm.org/D7873 llvm-svn: 230540
2015-02-26 04:42:41 +08:00
; CHECK: private constant { i32, [0 x i8], i32, [0 x i8], i32, [0 x i8], i32, [0 x i8], i32 } { i32 1, [0 x i8] zeroinitializer, i32 5, [0 x i8] zeroinitializer, i32 2, [0 x i8] zeroinitializer, i32 4, [0 x i8] zeroinitializer, i32 3 }
LowerBitSets: Introduce global layout builder. The builder is based on a layout algorithm that tries to keep members of small bit sets together. The new layout compresses Chromium's bit sets to around 15% of their original size. Differential Revision: http://reviews.llvm.org/D7796 llvm-svn: 230394
2015-02-25 07:17:02 +08:00
@a = constant i32 1
@b = constant i32 2
@c = constant i32 3
@d = constant i32 4
@e = constant i32 5
!0 = !{!"bitset1", i32* @a, i32 0}
!1 = !{!"bitset1", i32* @b, i32 0}
!2 = !{!"bitset1", i32* @c, i32 0}
!3 = !{!"bitset2", i32* @b, i32 0}
!4 = !{!"bitset2", i32* @d, i32 0}
!5 = !{!"bitset3", i32* @a, i32 0}
!6 = !{!"bitset3", i32* @e, i32 0}
!llvm.bitsets = !{ !0, !1, !2, !3, !4, !5, !6 }
declare i1 @llvm.bitset.test(i8* %ptr, metadata %bitset) nounwind readnone
define void @foo() {
%x = call i1 @llvm.bitset.test(i8* undef, metadata !"bitset1")
%y = call i1 @llvm.bitset.test(i8* undef, metadata !"bitset2")
%z = call i1 @llvm.bitset.test(i8* undef, metadata !"bitset3")
ret void
}