target/arm: Convert PMULL.64 to gvec

The gvec form will be needed for implementing SVE2.

Tested-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20200216214232.4230-4-richard.henderson@linaro.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 33 insertions, 0 deletions

diff --git a/target/arm/vec_helper.c b/target/arm/vec_helper.c
index 854de0e..79d2624 100644
--- a/target/arm/vec_helper.c
+++ b/target/arm/vec_helper.c
@@ -1164,3 +1164,36 @@ void HELPER(gvec_pmul_b)(void *vd, void *vn, void *vm, uint32_t desc)
     }
     clear_tail(d, opr_sz, simd_maxsz(desc));
 }
+
+/*
+ * 64x64->128 polynomial multiply.
+ * Because of the lanes are not accessed in strict columns,
+ * this probably cannot be turned into a generic helper.
+ */
+void HELPER(gvec_pmull_q)(void *vd, void *vn, void *vm, uint32_t desc)
+{
+    intptr_t i, j, opr_sz = simd_oprsz(desc);
+    intptr_t hi = simd_data(desc);
+    uint64_t *d = vd, *n = vn, *m = vm;
+
+    for (i = 0; i < opr_sz / 8; i += 2) {
+        uint64_t nn = n[i + hi];
+        uint64_t mm = m[i + hi];
+        uint64_t rhi = 0;
+        uint64_t rlo = 0;
+
+        /* Bit 0 can only influence the low 64-bit result.  */
+        if (nn & 1) {
+            rlo = mm;
+        }
+
+        for (j = 1; j < 64; ++j) {
+            uint64_t mask = -((nn >> j) & 1);
+            rlo ^= (mm << j) & mask;
+            rhi ^= (mm >> (64 - j)) & mask;
+        }
+        d[i] = rlo;
+        d[i + 1] = rhi;
+    }
+    clear_tail(d, opr_sz, simd_maxsz(desc));
+}