SSE instructions

[Bin Meng]

Hi Simon,

On Thu, Sep 28, 2023 at 10:41 AM Simon Glass <sjg at chromium.org> wrote:
>
> Hi Bin,
>
> U-Boot 64-bit on x86 disables sse, but when enabling Truetype I get a
> compiler error:
>
> drivers/video/console_truetype.c: In function 'frac':
> drivers/video/console_truetype.c:30:15: error: SSE register return
> with SSE disabled
> 30 | static double frac(double val)
>
> Do you know how to enable SSE for 64-bit?
>

The following patch could enable SSE for 64-bit:

diff --git a/arch/x86/config.mk b/arch/x86/config.mk
index 26ec1af2f0..250d7c9948 100644
--- a/arch/x86/config.mk
+++ b/arch/x86/config.mk
@@ -27,7 +27,7 @@ ifeq ($(IS_32BIT),y)
 PLATFORM_CPPFLAGS += -march=i386 -m32
 else
 PLATFORM_CPPFLAGS += $(if $(CONFIG_SPL_BUILD),,-fpic) -fno-common
-march=core2 -m64
-PLATFORM_CPPFLAGS += -mno-mmx -mno-sse
+PLATFORM_CPPFLAGS += -mno-mmx
 endif

However as Heinrich mentioned, U-Boot codes should be written in a
"floating point free" way.

The fix should really be updating console_truetype.c to use integers
instead of using float/double.

Regards,
Bin