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authorPeter Maydell <peter.maydell@linaro.org>2021-06-17 13:16:28 +0100
committerPeter Maydell <peter.maydell@linaro.org>2021-06-21 17:12:52 +0100
commitd93a468d1302f29afcb1e368fb39da3fe024fc39 (patch)
tree8fc675bf353a29557f5298ceff549866c2b6f24c /target/arm/translate-vfp.c
parent3e6d6e88d915d0fea1fbbf530801e2aec9df2d0d (diff)
downloadqemu-arm-d93a468d1302f29afcb1e368fb39da3fe024fc39.tar.gz
target/arm: Make VMOV scalar <-> gpreg beatwise for MVE
In a CPU with MVE, the VMOV (vector lane to general-purpose register) and VMOV (general-purpose register to vector lane) insns are not predicated, but they are subject to beatwise execution if they are not in an IT block. Since our implementation always executes all 4 beats in one tick, this means only that we need to handle PSR.ECI: * we must do the usual check for bad ECI state * we must advance ECI state if the insn succeeds * if ECI says we should not be executing the beat corresponding to the lane of the vector register being accessed then we should skip performing the move Note that if PSR.ECI is non-zero then we cannot be in an IT block. Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Reviewed-by: Richard Henderson <richard.henderson@linaro.org> Message-id: 20210617121628.20116-45-peter.maydell@linaro.org
Diffstat (limited to 'target/arm/translate-vfp.c')
-rw-r--r--target/arm/translate-vfp.c77
1 files changed, 71 insertions, 6 deletions
diff --git a/target/arm/translate-vfp.c b/target/arm/translate-vfp.c
index 86e43c02dc..b2991e21ec 100644
--- a/target/arm/translate-vfp.c
+++ b/target/arm/translate-vfp.c
@@ -581,6 +581,48 @@ static bool trans_VCVT(DisasContext *s, arg_VCVT *a)
return true;
}
+static bool mve_skip_vmov(DisasContext *s, int vn, int index, int size)
+{
+ /*
+ * In a CPU with MVE, the VMOV (vector lane to general-purpose register)
+ * and VMOV (general-purpose register to vector lane) insns are not
+ * predicated, but they are subject to beatwise execution if they are
+ * not in an IT block.
+ *
+ * Since our implementation always executes all 4 beats in one tick,
+ * this means only that if PSR.ECI says we should not be executing
+ * the beat corresponding to the lane of the vector register being
+ * accessed then we should skip performing the move, and that we need
+ * to do the usual check for bad ECI state and advance of ECI state.
+ *
+ * Note that if PSR.ECI is non-zero then we cannot be in an IT block.
+ *
+ * Return true if this VMOV scalar <-> gpreg should be skipped because
+ * the MVE PSR.ECI state says we skip the beat where the store happens.
+ */
+
+ /* Calculate the byte offset into Qn which we're going to access */
+ int ofs = (index << size) + ((vn & 1) * 8);
+
+ if (!dc_isar_feature(aa32_mve, s)) {
+ return false;
+ }
+
+ switch (s->eci) {
+ case ECI_NONE:
+ return false;
+ case ECI_A0:
+ return ofs < 4;
+ case ECI_A0A1:
+ return ofs < 8;
+ case ECI_A0A1A2:
+ case ECI_A0A1A2B0:
+ return ofs < 12;
+ default:
+ g_assert_not_reached();
+ }
+}
+
static bool trans_VMOV_to_gp(DisasContext *s, arg_VMOV_to_gp *a)
{
/* VMOV scalar to general purpose register */
@@ -603,14 +645,26 @@ static bool trans_VMOV_to_gp(DisasContext *s, arg_VMOV_to_gp *a)
return false;
}
+ if (dc_isar_feature(aa32_mve, s)) {
+ if (!mve_eci_check(s)) {
+ return true;
+ }
+ }
+
if (!vfp_access_check(s)) {
return true;
}
- tmp = tcg_temp_new_i32();
- read_neon_element32(tmp, a->vn, a->index, a->size | (a->u ? 0 : MO_SIGN));
- store_reg(s, a->rt, tmp);
+ if (!mve_skip_vmov(s, a->vn, a->index, a->size)) {
+ tmp = tcg_temp_new_i32();
+ read_neon_element32(tmp, a->vn, a->index,
+ a->size | (a->u ? 0 : MO_SIGN));
+ store_reg(s, a->rt, tmp);
+ }
+ if (dc_isar_feature(aa32_mve, s)) {
+ mve_update_and_store_eci(s);
+ }
return true;
}
@@ -636,14 +690,25 @@ static bool trans_VMOV_from_gp(DisasContext *s, arg_VMOV_from_gp *a)
return false;
}
+ if (dc_isar_feature(aa32_mve, s)) {
+ if (!mve_eci_check(s)) {
+ return true;
+ }
+ }
+
if (!vfp_access_check(s)) {
return true;
}
- tmp = load_reg(s, a->rt);
- write_neon_element32(tmp, a->vn, a->index, a->size);
- tcg_temp_free_i32(tmp);
+ if (!mve_skip_vmov(s, a->vn, a->index, a->size)) {
+ tmp = load_reg(s, a->rt);
+ write_neon_element32(tmp, a->vn, a->index, a->size);
+ tcg_temp_free_i32(tmp);
+ }
+ if (dc_isar_feature(aa32_mve, s)) {
+ mve_update_and_store_eci(s);
+ }
return true;
}