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authorJose Maria Casanova Crespo <jmcasanova@igalia.com>2018-05-03 01:38:47 +0200
committerDylan Baker <dylan@pnwbakers.com>2018-05-03 10:55:43 -0700
commit0d15a443fae48210ba16e7a3b664619ca5f89519 (patch)
tree9da0afa7e0ee8095e8c7e73e933ca6d128c9e04e
parent1e5c3fa29b82633a1818f7f107e2384ab9ab03e2 (diff)
intel/compiler: fix brw_imm_w for negative 16-bit integers
16-bit immediates need to replicate the 16-bit immediate value in both words of the 32-bit value. This needs to be careful to avoid sign-extension, which the previous implementation was not handling properly. For example, with the previous implementation, storing the value -3 would generate imm.d = 0xfffffffd due to signed integer sign extension, which is not correct. Instead, we should cast to uint16_t, which gives us the correct result: imm.ud = 0xfffdfffd. We only had a couple of cases hitting this path in the driver until now, one with value -1, which would work since all bits are one in this case, and another with value -2 in brw_clip_tri(), which would hit the aforementioned issue (this case only affects gen4 although we are not aware of whether this was causing an actual bug somewhere). v2: Make explicit uint32_t casting for left shift (Jason Ekstrand) Reviewed-by: Jason Ekstrand <jason@jlekstrand.net> Cc: "18.0 18.1" <mesa-stable@lists.freedesktop.org> (cherry picked from commit f0e6dacee529661393964725bed561c45405bae4)
-rw-r--r--src/intel/compiler/brw_reg.h2
1 files changed, 1 insertions, 1 deletions
diff --git a/src/intel/compiler/brw_reg.h b/src/intel/compiler/brw_reg.h
index dff9b970b2f..ac12ab3d2dd 100644
--- a/src/intel/compiler/brw_reg.h
+++ b/src/intel/compiler/brw_reg.h
@@ -705,7 +705,7 @@ static inline struct brw_reg
brw_imm_w(int16_t w)
{
struct brw_reg imm = brw_imm_reg(BRW_REGISTER_TYPE_W);
- imm.d = w | (w << 16);
+ imm.ud = (uint16_t)w | (uint32_t)(uint16_t)w << 16;
return imm;
}