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pan/bi: Decode M values in disasm 

This is rather complicated and mostly unused in real world code but
correct handling is required to disassemble branchy code.

Signed-off-by: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6793>
This commit is contained in:
Alyssa Rosenzweig 2020-09-19 16:06:22 -04:00 committed by Marge Bot
parent 9de34e16e0
commit 08a9e5e3e8
1 changed files with 59 additions and 0 deletions
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59
src/panfrost/bifrost/disassemble.c
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@ -386,6 +386,49 @@ dump_src(FILE *fp, unsigned src, struct bifrost_regs srcs, struct bi_constants *
}
}
/* Tables for decoding M0, or if M0 == 7, M1 respectively.
*
* XXX: It's not clear if the third entry of M1_table corresponding to (7, 2)
* should have PC_LO_HI in the EC1 slot, or it's a weird hybrid mode? I would
* say this needs testing but no code should ever actually use this mode.
*/
static const enum bi_constmod M1_table[7][2] = {
{ BI_CONSTMOD_NONE, BI_CONSTMOD_NONE },
{ BI_CONSTMOD_PC_LO, BI_CONSTMOD_NONE },
{ BI_CONSTMOD_PC_LO, BI_CONSTMOD_PC_LO },
{ ~0, ~0 },
{ BI_CONSTMOD_PC_HI, BI_CONSTMOD_NONE },
{ BI_CONSTMOD_PC_HI, BI_CONSTMOD_PC_HI },
{ BI_CONSTMOD_PC_LO, BI_CONSTMOD_NONE },
};
static const enum bi_constmod M2_table[4][2] = {
{ BI_CONSTMOD_PC_LO_HI, BI_CONSTMOD_NONE },
{ BI_CONSTMOD_PC_LO_HI, BI_CONSTMOD_PC_HI },
{ BI_CONSTMOD_PC_LO_HI, BI_CONSTMOD_PC_LO_HI },
{ BI_CONSTMOD_PC_LO_HI, BI_CONSTMOD_PC_HI },
};
static void
decode_M(enum bi_constmod *mod, unsigned M1, unsigned M2, bool single)
{
if (M1 >= 8) {
mod[0] = BI_CONSTMOD_NONE;
if (!single)
mod[1] = BI_CONSTMOD_NONE;
return;
} else if (M1 == 7) {
assert(M2 < 4);
memcpy(mod, M2_table[M2], sizeof(*mod) * (single ? 1 : 2));
} else {
assert(M1 != 3);
memcpy(mod, M1_table[M1], sizeof(*mod) * (single ? 1 : 2));
}
}
static bool dump_clause(FILE *fp, uint32_t *words, unsigned *size, unsigned offset, bool verbose)
{
// State for a decoded clause
@ -449,6 +492,7 @@ static bool dump_clause(FILE *fp, uint32_t *words, unsigned *size, unsigned offs
instrs[2].add_bits = bits(words[3], 0, 17) | bits(words[3], 29, 32) << 17;
instrs[2].fma_bits |= bits(words[2], 19, 32) << 10;
consts.raw[0] = const0;
decode_M(&consts.mods[0], bits(words[2], 4, 8), bits(words[2], 8, 12), true);
num_instrs = 3;
num_consts = 1;
done = stop;
@ -470,6 +514,7 @@ static bool dump_clause(FILE *fp, uint32_t *words, unsigned *size, unsigned offs
instrs[5].add_bits = bits(words[3], 0, 17) | bits(words[3], 29, 32) << 17;
instrs[5].fma_bits |= bits(words[2], 19, 32) << 10;
consts.raw[0] = const0;
decode_M(&consts.mods[0], bits(words[2], 4, 8), bits(words[2], 8, 12), true);
num_instrs = 6;
num_consts = 1;
done = stop;
@ -568,6 +613,20 @@ static bool dump_clause(FILE *fp, uint32_t *words, unsigned *size, unsigned offs
consts.raw[const_idx] = const0;
consts.raw[const_idx + 1] = const1;
/* Calculate M values from A, B and 4-bit
* unsigned arithmetic */
signed A1 = bits(words[2], 0, 4);
signed B1 = bits(words[3], 28, 32);
signed A2 = bits(words[1], 0, 4);
signed B2 = bits(words[2], 28, 32);
unsigned M1 = (A1 - B1) % 16;
unsigned M2 = (A2 - B2) % 16;
decode_M(&consts.mods[const_idx], M1, M2, false);
done = stop;
break;
}