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From e522b1d09d3536ddc15459b4259150f4a53ee65a Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers@google.com>
Date: Thu, 4 Apr 2024 20:16:33 -0400
Subject: [PATCH] lib/x86: increase AVX-VNNI gcc prerequisite to 12.1
Although gcc 11.1 supports AVX-VNNI, a popular distro pairs it with a
binutils version that does not. Require gcc 12 instead.
Resolves https://github.com/ebiggers/libdeflate/issues/365
---
lib/x86/adler32_impl.h | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
--- a/lib/x86/adler32_impl.h
+++ b/lib/x86/adler32_impl.h
@@ -52,8 +52,15 @@
/*
* AVX-VNNI implementation. This is used on CPUs that have AVX2 and AVX-VNNI
* but don't have AVX-512, for example Intel Alder Lake.
+ *
+ * Unusually for a new CPU feature, gcc added support for the AVX-VNNI
+ * intrinsics (in gcc 11.1) slightly before binutils added support for
+ * assembling AVX-VNNI instructions (in binutils 2.36). Distros can reasonably
+ * have gcc 11 with binutils 2.35. Because of this issue, we check for gcc 12
+ * instead of gcc 11. (libdeflate supports direct compilation without a
+ * configure step, so checking the binutils version is not always an option.)
*/
-#if GCC_PREREQ(11, 1) || CLANG_PREREQ(12, 0, 13000000) || MSVC_PREREQ(1930)
+#if GCC_PREREQ(12, 1) || CLANG_PREREQ(12, 0, 13000000) || MSVC_PREREQ(1930)
# define adler32_x86_avx2_vnni adler32_x86_avx2_vnni
# define SUFFIX _avx2_vnni
# define ATTRIBUTES _target_attribute("avx2,avxvnni")
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