6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2025-07-25 13:24:46 +00:00
Code Issues Projects Releases Wiki Activity

LowerBitSets: Align referenced globals.

Browse Source 
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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@230540 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Peter Collingbourne
2015-02-25 20:42:41 +00:00
parent 814efef67f
commit d63e5ad9c5
6 changed files with 101 additions and 73 deletions
Download Patch File Download Diff File Expand all files Collapse all files

2
test/Transforms/LowerBitSets/layout.ll
View File

@@ -6,7 +6,7 @@ target datalayout = "e-p:32:32"
; (see GlobalLayoutBuilder in include/llvm/Transforms/IPO/LowerBitSets.h).
; The chosen layout in this case is a, e, b, d, c.
; CHECK: private constant { i32, i32, i32, i32, i32 } { i32 1, i32 5, i32 2, i32 4, i32 3 }
; 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 }
@a = constant i32 1
@b = constant i32 2
@c = constant i32 3