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

[Jeff Law <law@redhat.com>]

On 6/4/19 7:11 AM, Jozef Lawrynowicz wrote:
> 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?
> 
> 
> 0002-MSP430-Force-the-src-operand-of-a-HImode-shift-into-.patch
> 
> From e609f63d49227ce385316896dde6a476f5f27db7 Mon Sep 17 00:00:00 2001
> From: Jozef Lawrynowicz <jozef.l@mittosystems.com>
> Date: Mon, 13 May 2019 17:48:00 +0100
> Subject: [PATCH 2/4] MSP430: Force the src operand of a HImode shift into a
>  register if it is in memory
> 
> gcc/ChangeLog
> 
> 2019-06-04  Jozef Lawrynowicz  <jozef.l@mittosystems.com>
> 
> 	* config/msp430/msp430.md (ashlhi3): Force shift src operand into a
> 	register if it is in memory, so the shift can be emulated with a rotate
> 	instruction.
> 	(ashrhi3): Likewise.
> 	(lshrhi3): Likewise.
> 
> gcc/testsuite/ChangeLog
> 
> 2019-06-04  Jozef Lawrynowicz  <jozef.l@mittosystems.com>
> 
> 	* gcc.target/msp430/emulate-slli.c: New test.
> 	* gcc.target/msp430/emulate-srai.c: New test.
> 	* gcc.target/msp430/emulate-srli.c: New test.
OK
jeff
> ---