aco: shrink ssa_info

Reorder members so that it's 16 bytes instead of 24.

Signed-off-by: Rhys Perry <pendingchaos02@gmail.com>
Reviewed-by: Daniel Schürmann <daniel@schuermann.dev>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/5281>

src/amd/compiler/aco_optimizer.cpp

@@ -102,11 +102,11 @@ static constexpr uint32_t val_labels = label_constant_32bit | label_constant_64b
 
 struct ssa_info {
    uint32_t val;
+   uint32_t label;
    union {
       Temp temp;
       Instruction* instr;
    };
-   uint32_t label;
 
    ssa_info() : label(0) {}