[PATCH][MSP430][2/4] Emulate 16-bit shifts with rotate insn when src operand is originally in memory

Jozef Lawrynowicz jozef.l@mittosystems.com
Tue Jun 4 13:11:00 GMT 2019


This patch reduces code size by enabling the emulation of some 16-bit shift
instructions with the native rotate instructions, when the source operand is in
memory. This is achieved by forcing the source operand into a register.

For the following program, the below code size reduction is observed:
  int a;

  int
  main (void)
  {
    a = a << 4;
    return 0;
  }

With shift patch 1:
   text    data     bss     dec     hex filename
    484      12      20     516     204 a.out
With new patch:
   text    data     bss     dec     hex filename
    452      12      20     484     1e4 a.out

Ok for trunk?
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