tcg: Adjust simd_desc size encoding

With larger vector sizes, it turns out oprsz == maxsz, and we only
need to represent mismatch for oprsz <= 32.  We do, however, need
to represent larger oprsz and do so without reducing SIMD_DATA_BITS.

Reduce the size of the oprsz field and increase the maxsz field.
Steal the oprsz value of 24 to indicate equality with maxsz.

Tested-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Frank Chang <frank.chang@sifive.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 27 insertions, 8 deletions

diff --git a/tcg/tcg-op-gvec.c b/tcg/tcg-op-gvec.c
index 7ebd9e8298..ddbe06b71a 100644
--- a/tcg/tcg-op-gvec.c
+++ b/tcg/tcg-op-gvec.c
@@ -37,11 +37,21 @@ static const TCGOpcode vecop_list_empty[1] = { 0 };
    of the operand offsets so that we can check them all at once.  */
 static void check_size_align(uint32_t oprsz, uint32_t maxsz, uint32_t ofs)
 {
-    uint32_t opr_align = oprsz >= 16 ? 15 : 7;
-    uint32_t max_align = maxsz >= 16 || oprsz >= 16 ? 15 : 7;
-    tcg_debug_assert(oprsz > 0);
-    tcg_debug_assert(oprsz <= maxsz);
-    tcg_debug_assert((oprsz & opr_align) == 0);
+    uint32_t max_align;
+
+    switch (oprsz) {
+    case 8:
+    case 16:
+    case 32:
+        tcg_debug_assert(oprsz <= maxsz);
+        break;
+    default:
+        tcg_debug_assert(oprsz == maxsz);
+        break;
+    }
+    tcg_debug_assert(maxsz <= (8 << SIMD_MAXSZ_BITS));
+
+    max_align = maxsz >= 16 ? 15 : 7;
     tcg_debug_assert((maxsz & max_align) == 0);
     tcg_debug_assert((ofs & max_align) == 0);
 }
@@ -77,12 +87,21 @@ uint32_t simd_desc(uint32_t oprsz, uint32_t maxsz, int32_t data)
 {
     uint32_t desc = 0;
 
-    assert(oprsz % 8 == 0 && oprsz <= (8 << SIMD_OPRSZ_BITS));
-    assert(maxsz % 8 == 0 && maxsz <= (8 << SIMD_MAXSZ_BITS));
-    assert(data == sextract32(data, 0, SIMD_DATA_BITS));
+    check_size_align(oprsz, maxsz, 0);
+    tcg_debug_assert(data == sextract32(data, 0, SIMD_DATA_BITS));
 
     oprsz = (oprsz / 8) - 1;
     maxsz = (maxsz / 8) - 1;
+
+    /*
+     * We have just asserted in check_size_align that either
+     * oprsz is {8,16,32} or matches maxsz.  Encode the final
+     * case with '2', as that would otherwise map to 24.
+     */
+    if (oprsz == maxsz) {
+        oprsz = 2;
+    }
+
     desc = deposit32(desc, SIMD_OPRSZ_SHIFT, SIMD_OPRSZ_BITS, oprsz);
     desc = deposit32(desc, SIMD_MAXSZ_SHIFT, SIMD_MAXSZ_BITS, maxsz);
     desc = deposit32(desc, SIMD_DATA_SHIFT, SIMD_DATA_BITS, data);