GCC emits the instruction pair...
mov r#, 0x####
movt r#, 0x####
for loading a 32-bit value into a register. When the compile-time value is less than 16-bits, the movt instruction is unnecessary since the mov (immediate) instruction will load the full value and zero the high bits.
For example, I find this pattern a lot in compiled code:
mov r#, 0x####
movt r#, 0x0
The emitted code for the movt is larger than necessary and performance takes a small hit.
GCC emits the instruction pair...
for loading a 32-bit value into a register. When the compile-time value is less than 16-bits, the movt instruction is unnecessary since the mov (immediate) instruction will load the full value and zero the high bits.
For example, I find this pattern a lot in compiled code:
The emitted code for the movt is larger than necessary and performance takes a small hit.