tcg: Remove CONFIG_VECTOR16

The comment in tcg-runtime-gvec.c about CONFIG_VECTOR16 says that
tcg-op-gvec.c has eliminated size 8 vectors, and only passes on
multiples of 16.  This may have been true of the first few operations,
but is not true of all operations.

In particular, multiply, shift by scalar, and compare of 8- and 16-bit
elements are not expanded inline if host vector operations are not
supported.

For an x86_64 host that does not support AVX, this means that we will
fall back to the helper, which will attempt to use SSE instructions,
which will SEGV on an invalid 8-byte aligned memory operation.

This patch simply removes the CONFIG_VECTOR16 code and configuration
without further simplification.

Buglink: https://bugs.launchpad.net/bugs/1863508
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

diff --git a/accel/tcg/tcg-runtime-gvec.c b/accel/tcg/tcg-runtime-gvec.c
index 5b1902d5919b3342a831bd6ca4a3d529e2ea9a82..00da0938a5af29472c99028af20be49d3d26f9a1 100644 (file)
--- a/accel/tcg/tcg-runtime-gvec.c
+++ b/accel/tcg/tcg-runtime-gvec.c
@@ -24,32 +24,6 @@
 #include "tcg/tcg-gvec-desc.h"
 
 
-/* Virtually all hosts support 16-byte vectors.  Those that don't can emulate
- * them via GCC's generic vector extension.  This turns out to be simpler and
- * more reliable than getting the compiler to autovectorize.
- *
- * In tcg-op-gvec.c, we asserted that both the size and alignment of the data
- * are multiples of 16.
- *
- * When the compiler does not support all of the operations we require, the
- * loops are written so that we can always fall back on the base types.
- */
-#ifdef CONFIG_VECTOR16
-typedef uint8_t vec8 __attribute__((vector_size(16)));
-typedef uint16_t vec16 __attribute__((vector_size(16)));
-typedef uint32_t vec32 __attribute__((vector_size(16)));
-typedef uint64_t vec64 __attribute__((vector_size(16)));
-
-typedef int8_t svec8 __attribute__((vector_size(16)));
-typedef int16_t svec16 __attribute__((vector_size(16)));
-typedef int32_t svec32 __attribute__((vector_size(16)));
-typedef int64_t svec64 __attribute__((vector_size(16)));
-
-#define DUP16(X)  { X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X }
-#define DUP8(X)   { X, X, X, X, X, X, X, X }
-#define DUP4(X)   { X, X, X, X }
-#define DUP2(X)   { X, X }
-#else
 typedef uint8_t vec8;
 typedef uint16_t vec16;
 typedef uint32_t vec32;
@@ -64,7 +38,6 @@ typedef int64_t svec64;
 #define DUP8(X)   X
 #define DUP4(X)   X
 #define DUP2(X)   X
-#endif /* CONFIG_VECTOR16 */
 
 static inline void clear_high(void *d, intptr_t oprsz, uint32_t desc)
 {
@@ -917,13 +890,7 @@ void HELPER(gvec_sar64v)(void *d, void *a, void *b, uint32_t desc)
     clear_high(d, oprsz, desc);
 }
 
-/* If vectors are enabled, the compiler fills in -1 for true.
-   Otherwise, we must take care of this by hand.  */
-#ifdef CONFIG_VECTOR16
-# define DO_CMP0(X)  X
-#else
-# define DO_CMP0(X)  -(X)
-#endif
+#define DO_CMP0(X)  -(X)
 
 #define DO_CMP1(NAME, TYPE, OP)                                            \
 void HELPER(NAME)(void *d, void *a, void *b, uint32_t desc)                \

diff --git a/configure b/configure
index eb49bb6680c1863afe74505c42ccc1e71885186a..47b8dea78a1ecd4ddfcfb930478fd7192a02a76c 100755 (executable)
--- a/configure
+++ b/configure
@@ -5711,58 +5711,6 @@ if  test "$plugins" = "yes" &&
       "for this purpose. You can't build with --static."
 fi
 
-########################################
-# See if 16-byte vector operations are supported.
-# Even without a vector unit the compiler may expand these.
-# There is a bug in old GCC for PPC that crashes here.
-# Unfortunately it's the system compiler for Centos 7.
-
-cat > $TMPC << EOF
-typedef unsigned char U1 __attribute__((vector_size(16)));
-typedef unsigned short U2 __attribute__((vector_size(16)));
-typedef unsigned int U4 __attribute__((vector_size(16)));
-typedef unsigned long long U8 __attribute__((vector_size(16)));
-typedef signed char S1 __attribute__((vector_size(16)));
-typedef signed short S2 __attribute__((vector_size(16)));
-typedef signed int S4 __attribute__((vector_size(16)));
-typedef signed long long S8 __attribute__((vector_size(16)));
-static U1 a1, b1;
-static U2 a2, b2;
-static U4 a4, b4;
-static U8 a8, b8;
-static S1 c1;
-static S2 c2;
-static S4 c4;
-static S8 c8;
-static int i;
-void helper(void *d, void *a, int shift, int i);
-void helper(void *d, void *a, int shift, int i)
-{
-  *(U1 *)(d + i) = *(U1 *)(a + i) << shift;
-  *(U2 *)(d + i) = *(U2 *)(a + i) << shift;
-  *(U4 *)(d + i) = *(U4 *)(a + i) << shift;
-  *(U8 *)(d + i) = *(U8 *)(a + i) << shift;
-}
-int main(void)
-{
-  a1 += b1; a2 += b2; a4 += b4; a8 += b8;
-  a1 -= b1; a2 -= b2; a4 -= b4; a8 -= b8;
-  a1 *= b1; a2 *= b2; a4 *= b4; a8 *= b8;
-  a1 &= b1; a2 &= b2; a4 &= b4; a8 &= b8;
-  a1 |= b1; a2 |= b2; a4 |= b4; a8 |= b8;
-  a1 ^= b1; a2 ^= b2; a4 ^= b4; a8 ^= b8;
-  a1 <<= i; a2 <<= i; a4 <<= i; a8 <<= i;
-  a1 >>= i; a2 >>= i; a4 >>= i; a8 >>= i;
-  c1 >>= i; c2 >>= i; c4 >>= i; c8 >>= i;
-  return 0;
-}
-EOF
-
-vector16=no
-if compile_prog "" "" ; then
-  vector16=yes
-fi
-
 ########################################
 # See if __attribute__((alias)) is supported.
 # This false for Xcode 9, but has been remedied for Xcode 10.
@@ -7383,10 +7331,6 @@ if test "$atomic64" = "yes" ; then
   echo "CONFIG_ATOMIC64=y" >> $config_host_mak
 fi
 
-if test "$vector16" = "yes" ; then
-  echo "CONFIG_VECTOR16=y" >> $config_host_mak
-fi
-
 if test "$attralias" = "yes" ; then
   echo "CONFIG_ATTRIBUTE_ALIAS=y" >> $config_host_mak
 fi