gh-160333: remove SIMD support for HACL* BLAKE-2

The vectorized BLAKE-2 implementations were only enabled on some x86-64
platforms and caused build failures on many others. `_blake2` and `_hmac`
now always use the portable HACL* implementations.

The SIMD sources are no longer vendored; their headers are kept since
`Hacl_Streaming_HMAC.c` includes them unconditionally.

Author: picnixz

Doc/whatsnew/3.16.rst

@@ -1299,6 +1299,14 @@ Build changes
 
   (Contributed by Stan Ulbrych, Florian Mayer and AnnaAr321 in :gh:`156049`.)
 
+* Remove SIMD support for the HACL\* implementation of BLAKE-2 used by
+  :mod:`hashlib` and :mod:`hmac`. The vectorized implementations were only
+  enabled on some x86-64 platforms and caused build failures on many others.
+  The :program:`configure` script no longer checks for the compiler flags
+  needed to build them.
+
+  (Contributed by Bénédikt Tran in :gh:`160333`.)
+
 
 C API changes
 =============

Makefile.pre.in

@@ -238,8 +238,6 @@ LIBEXPAT_A= Modules/expat/libexpat.a
 # HACL* build configuration
 LIBHACL_CFLAGS=@LIBHACL_CFLAGS@
 LIBHACL_LDFLAGS=@LIBHACL_LDFLAGS@
-LIBHACL_BLAKE2_SIMD128_CFLAGS=@LIBHACL_SIMD128_FLAGS@ -DHACL_CAN_COMPILE_VEC128
-LIBHACL_BLAKE2_SIMD256_CFLAGS=@LIBHACL_SIMD256_FLAGS@ -DHACL_CAN_COMPILE_VEC256
 
 # Module state, compiler flags and linker flags
 # Empty CFLAGS and LDFLAGS are omitted.
@@ -673,14 +671,10 @@ LIBHACL_SHA3_OBJS= \
 LIBHACL_SHA3_LIB_STATIC=Modules/_hacl/libHacl_Hash_SHA3.a
 LIBHACL_SHA3_LIB_SHARED=$(LIBHACL_SHA3_OBJS)
 
-LIBHACL_BLAKE2_SIMD128_OBJS=@LIBHACL_BLAKE2_SIMD128_OBJS@
-LIBHACL_BLAKE2_SIMD256_OBJS=@LIBHACL_BLAKE2_SIMD256_OBJS@
 LIBHACL_BLAKE2_OBJS= \
 		Modules/_hacl/Hacl_Hash_Blake2s.o \
 		Modules/_hacl/Hacl_Hash_Blake2b.o \
-		Modules/_hacl/Lib_Memzero0.o \
-		$(LIBHACL_BLAKE2_SIMD128_OBJS) \
-		$(LIBHACL_BLAKE2_SIMD256_OBJS)
+		Modules/_hacl/Lib_Memzero0.o
 LIBHACL_BLAKE2_LIB_STATIC=Modules/_hacl/libHacl_Hash_BLAKE2.a
 LIBHACL_BLAKE2_LIB_SHARED=$(LIBHACL_BLAKE2_OBJS)
 
@@ -1530,14 +1524,6 @@ Modules/_hacl/Hacl_Hash_Blake2s.o: $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2s.c $
 	$(CC) -c $(LIBHACL_CFLAGS) -o $@ $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2s.c
 Modules/_hacl/Hacl_Hash_Blake2b.o: $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2b.c $(LIBHACL_BLAKE2_HEADERS)
 	$(CC) -c $(LIBHACL_CFLAGS) -o $@ $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2b.c
-Modules/_hacl/Hacl_Hash_Blake2s_Simd128.o: $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2s_Simd128.c $(LIBHACL_BLAKE2_HEADERS)
-	$(CC) -c $(LIBHACL_CFLAGS) $(LIBHACL_BLAKE2_SIMD128_CFLAGS) -o $@ $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2s_Simd128.c
-Modules/_hacl/Hacl_Hash_Blake2s_Simd128_universal2.o: $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2s_Simd128_universal2.c $(LIBHACL_BLAKE2_HEADERS)
-	$(CC) -c $(LIBHACL_CFLAGS) $(LIBHACL_BLAKE2_SIMD128_CFLAGS) -o $@ $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2s_Simd128_universal2.c
-Modules/_hacl/Hacl_Hash_Blake2b_Simd256.o: $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2b_Simd256.c $(LIBHACL_BLAKE2_HEADERS)
-	$(CC) -c $(LIBHACL_CFLAGS) $(LIBHACL_BLAKE2_SIMD256_CFLAGS) -o $@ $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2b_Simd256.c
-Modules/_hacl/Hacl_Hash_Blake2b_Simd256_universal2.o: $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2b_Simd256_universal2.c $(LIBHACL_BLAKE2_HEADERS)
-	$(CC) -c $(LIBHACL_CFLAGS) $(LIBHACL_BLAKE2_SIMD256_CFLAGS) -o $@ $(srcdir)/Modules/_hacl/Hacl_Hash_Blake2b_Simd256_universal2.c
 $(LIBHACL_BLAKE2_LIB_STATIC): $(LIBHACL_BLAKE2_OBJS)
 	-rm -f $@
 	$(AR) $(ARFLAGS) $@ $(LIBHACL_BLAKE2_OBJS)

Misc/NEWS.d/next/Build/2026-10-22-13-09-58.gh-issue-160333.QqQUOt.rst

@@ -0,0 +1,4 @@
+Remove SIMD support for the HACL\* implementation of BLAKE-2 used by
+:mod:`hashlib` and :mod:`hmac`. The vectorized implementations were only
+enabled on some x86-64 platforms and caused build failures on many others.
+Patch by Bénédikt Tran.