[glibc] Set Prefer_No_AVX512 flag for hygon platform

H.J. Lu hjl@sourceware.org
Tue Nov 11 02:53:10 GMT 2025


https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1707b233822a503f787ae1b4abdd07949c3ee691

commit 1707b233822a503f787ae1b4abdd07949c3ee691
Author: Xie jiamei <xiejiamei@hygon.cn>
Date:   Tue Nov 11 10:28:54 2025 +0800

    Set Prefer_No_AVX512 flag for hygon platform
    
    Benchmarks indicate evex can be more profitable on Hygon hardware
    than AVX512. So add Prefer_No_AVX512 to make it run with evex.
    
    Change-Id: Icc59492f71fde7a783a8bd315714ffd6f7ecaf29
    Signed-off-by: Li jing <lijing@hygon.cn>
    Signed-off-by: Xie jiamei <xiejiamei@hygon.cn>

Diff:
---
 sysdeps/x86/cpu-features.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/sysdeps/x86/cpu-features.c b/sysdeps/x86/cpu-features.c
index 5d4437ffdf..ecf10ce44d 100644
--- a/sysdeps/x86/cpu-features.c
+++ b/sysdeps/x86/cpu-features.c
@@ -1129,6 +1129,13 @@ disable_tsx:
 	  cpu_features->preferred[index_arch_AVX_Fast_Unaligned_Load]
 	    &= ~bit_arch_AVX_Fast_Unaligned_Load;
 	}
+      else if (model == 0x7)
+	{
+	  /* Benchmarks indicate evex can be more profitable on Hygon
+	     hardware than AVX512.  */
+	  cpu_features->preferred[index_arch_Prefer_No_AVX512]
+	    |= bit_arch_Prefer_No_AVX512;
+	}
     }
   else
     {


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