Mesa (master): aco: fix adjust_vertex_fetch_alpha

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Module: Mesa
Branch: master
Commit: f7575fa71fb026003800bc5e376393d1cfab7113
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=f7575fa71fb026003800bc5e376393d1cfab7113

Author: Rhys Perry <pendingchaos02 at gmail.com>
Date:   Tue Feb  9 21:33:43 2021 +0000

aco: fix adjust_vertex_fetch_alpha

These offsets were wrong and didn't match the old behaviour.

Signed-off-by: Rhys Perry <pendingchaos02 at gmail.com>
Reviewed-by: Daniel Schürmann <daniel at schuermann.dev>
Fixes: e8220e106bf ("aco: optimize AC_FETCH_FORMAT_SNORM alpha adjust")
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8935>

---

 src/amd/compiler/aco_instruction_selection.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/amd/compiler/aco_instruction_selection.cpp b/src/amd/compiler/aco_instruction_selection.cpp
index e21b71b99ff..7eb95bc43f7 100644
--- a/src/amd/compiler/aco_instruction_selection.cpp
+++ b/src/amd/compiler/aco_instruction_selection.cpp
@@ -4854,7 +4854,7 @@ Temp adjust_vertex_fetch_alpha(isel_context *ctx, unsigned adjustment, Temp alph
     * and happen to contain 0, 1, 2, 3 as the two LSBs of the
     * exponent.
     */
-   unsigned offset = adjustment == AC_FETCH_FORMAT_SNORM ? 7u : 30u;
+   unsigned offset = adjustment == AC_FETCH_FORMAT_SNORM ? 23u : 0u;
    alpha = bld.vop3(aco_opcode::v_bfe_i32, bld.def(v1), alpha, Operand(offset), Operand(2u));
 
    /* Convert back to the right type. */