Re: [X86 PATCH] Implement doubleword shift left by 1 bit using add+adc.

2023-10-05 Thread Uros Bizjak
On Thu, Oct 5, 2023 at 1:45 PM Roger Sayle wrote: > > Doh! ENOPATCH. > > > -Original Message- > > From: Roger Sayle > > Sent: 05 October 2023 12:44 > > To: 'gcc-patches@gcc.gnu.org' > > Cc: 'Uros Bizjak' > > Subject: [X86 PATCH] Implement d

RE: [X86 PATCH] Implement doubleword shift left by 1 bit using add+adc.

2023-10-05 Thread Roger Sayle
Doh! ENOPATCH. > -Original Message- > From: Roger Sayle > Sent: 05 October 2023 12:44 > To: 'gcc-patches@gcc.gnu.org' > Cc: 'Uros Bizjak' > Subject: [X86 PATCH] Implement doubleword shift left by 1 bit using add+adc. > > > This patch tweaks the i386

[X86 PATCH] Implement doubleword shift left by 1 bit using add+adc.

2023-10-05 Thread Roger Sayle
This patch tweaks the i386 back-end's ix86_split_ashl to implement doubleword left shifts by 1 bit, using an add followed by an add-with-carry (i.e. a doubleword x+x) instead of using the x86's shld instruction. The replacement sequence both requires fewer bytes and is faster on both Intel and