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intel/fs: Fix lowering of dword multiplication by 16-bit constant 

Existing code was ignoring whether the type of the immediate source
was signed or not.  If the source was signed, it would ignore small
negative values but it also would wrongly accept values between
INT16_MAX and UINT16_MAX, causing the atual value to later be
reinterpreted as a negative number (under 16-bits).

Fixes tests/shaders/glsl-mul-const.shader_test in Piglit for platforms
that don't support MUL with 32x32 types, including ICL and TGL.

Closes: https://gitlab.freedesktop.org/mesa/mesa/issues/2186
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>
This commit is contained in:
Caio Marcelo de Oliveira Filho 2019-12-16 13:37:41 -08:00
parent 66013cb1be
commit 2137be22fa
1 changed files with 4 additions and 2 deletions
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6
src/intel/compiler/brw_fs.cpp
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@ -3908,7 +3908,10 @@ fs_visitor::lower_mul_dword_inst(fs_inst *inst, bblock_t *block)
{
const fs_builder ibld(this, block, inst);
if (inst->src[1].file == IMM && inst->src[1].ud < (1 << 16)) {
const bool ud = (inst->src[1].type == BRW_REGISTER_TYPE_UD);
if (inst->src[1].file == IMM &&
(( ud && inst->src[1].ud <= UINT16_MAX) ||
(!ud && inst->src[1].d <= INT16_MAX && inst->src[1].d >= INT16_MIN))) {
/* The MUL instruction isn't commutative. On Gen <= 6, only the low
* 16-bits of src0 are read, and on Gen >= 7 only the low 16-bits of
* src1 are used.
@ -3921,7 +3924,6 @@ fs_visitor::lower_mul_dword_inst(fs_inst *inst, bblock_t *block)
ibld.MOV(imm, inst->src[1]);
ibld.MUL(inst->dst, imm, inst->src[0]);
} else {
const bool ud = (inst->src[1].type == BRW_REGISTER_TYPE_UD);
ibld.MUL(inst->dst, inst->src[0],
ud ? brw_imm_uw(inst->src[1].ud)
: brw_imm_w(inst->src[1].d));