aboutsummaryrefslogtreecommitdiffstats
path: root/lib/Target/Alpha/README.txt
blob: 2d1909a42c57e60fdffe74ed85aeb2d3d9694e70 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
Fix Ordered/Unordered FP stuff


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
improve bytezap opertunities
ulong %foo(ulong %y) {
entry:
        %tmp = and ulong %y,  65535
        %tmp2 = shr ulong %tmp,  ubyte 3
        ret ulong %tmp2
}


compiles to a 3 instruction sequence without instcombine
        zapnot $16,3,$0
        srl $0,3,$0
        ret $31,($26),1
 
After instcombine you get
ulong %foo(ulong %y) {
entry:
        %tmp = shr ulong %y, ubyte 3            ; <ulong> [#uses=1]
        %tmp2 = and ulong %tmp, 8191            ; <ulong> [#uses=1]
        ret ulong %tmp2
}

which compiles to
        lda $0,8191($31)
        srl $16,3,$1
        and $1,$0,$0
        ret $31,($26),1