[Mesa-stable] [PATCH v3] intel/compiler: fix 16-bit int brw_negate_immediate and brw_abs_immediate

[Jose Maria Casanova Crespo]

>From Intel Skylake PRM, vol 07, "Immediate" section (page 768):

"For a word, unsigned word, or half-float immediate data,
software must replicate the same 16-bit immediate value to both
the lower word and the high word of the 32-bit immediate field
in a GEN instruction."

This fixes the int16/uint16 negate and abs immediates that weren't
taking into account the replication in lower and upper words.

v2: Integer cases are different to Float cases. (Jason Ekstrand)
    Included reference to PRM (Jose Maria Casanova)
v3: Make explicit uint32_t casting for left shift (Jason Ekstrand)
    Split half float implementation. (Jason Ekstrand)
    Fix brw_abs_immediate (Jose Maria Casanova)

Cc: "18 . 0 18 . 1" <mesa-stable at lists.freedesktop.org>
---
 src/intel/compiler/brw_shader.cpp | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/src/intel/compiler/brw_shader.cpp b/src/intel/compiler/brw_shader.cpp
index 9cdf9fcb23d..284c2e8233c 100644
--- a/src/intel/compiler/brw_shader.cpp
+++ b/src/intel/compiler/brw_shader.cpp
@@ -580,9 +580,11 @@ brw_negate_immediate(enum brw_reg_type type, struct brw_reg *reg)
       reg->d = -reg->d;
       return true;
    case BRW_REGISTER_TYPE_W:
-   case BRW_REGISTER_TYPE_UW:
-      reg->d = -(int16_t)reg->ud;
+   case BRW_REGISTER_TYPE_UW: {
+      uint16_t value = -(int16_t)reg->ud;
+      reg->ud = value | (uint32_t)value << 16;
       return true;
+   }
    case BRW_REGISTER_TYPE_F:
       reg->f = -reg->f;
       return true;
@@ -618,9 +620,11 @@ brw_abs_immediate(enum brw_reg_type type, struct brw_reg *reg)
    case BRW_REGISTER_TYPE_D:
       reg->d = abs(reg->d);
       return true;
-   case BRW_REGISTER_TYPE_W:
-      reg->d = abs((int16_t)reg->ud);
+   case BRW_REGISTER_TYPE_W: {
+      uint16_t value = abs((int16_t)reg->ud);
+      reg->ud = value | (uint32_t)value << 16;
       return true;
+   }
    case BRW_REGISTER_TYPE_F:
       reg->f = fabsf(reg->f);
       return true;
-- 
2.14.3