Files
llvm/test/CodeGen/PowerPC
QingShan Zhang d59be50a0a [DAGCombine] Match a pattern where a wide type scalar value is stored by several narrow stores
This opportunity is found from spec 2017 557.xz_r. And it is used by the sha encrypt/decrypt. See sha-2/sha512.c

static void store64(u64 x, unsigned char* y)
{
    for(int i = 0; i != 8; ++i)
        y[i] = (x >> ((7-i) * 8)) & 255;
}

static u64 load64(const unsigned char* y)
{
    u64 res = 0;
    for(int i = 0; i != 8; ++i)
        res |= (u64)(y[i]) << ((7-i) * 8);
    return res;
}
The load64 has been implemented by https://reviews.llvm.org/D26149
This patch is trying to implement the store pattern.

Match a pattern where a wide type scalar value is stored by several narrow
stores. Fold it into a single store or a BSWAP and a store if the targets
supports it.

Assuming little endian target:
i8 *p = ...
i32 val = ...
p[0] = (val >> 0) & 0xFF;
p[1] = (val >> 8) & 0xFF;
p[2] = (val >> 16) & 0xFF;
p[3] = (val >> 24) & 0xFF;

>
*((i32)p) = val;

i8 *p = ...
i32 val = ...
p[0] = (val >> 24) & 0xFF;
p[1] = (val >> 16) & 0xFF;
p[2] = (val >> 8) & 0xFF;
p[3] = (val >> 0) & 0xFF;

>
*((i32)p) = BSWAP(val);

Differential Revision: https://reviews.llvm.org/D61843



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@362472 91177308-0d34-0410-b5e6-96231b3b80d8
2019-06-04 08:53:53 +00:00
..
2018-09-07 07:56:05 +00:00
2019-05-14 03:11:24 +00:00
2019-04-29 23:25:33 +00:00
2019-03-29 17:35:56 +00:00
2017-10-10 08:46:10 +00:00
2018-12-19 15:21:07 +00:00
2017-01-22 20:28:56 +00:00
2019-05-16 12:50:39 +00:00