[Qemu-devel] [PATCH 5/8] target/ppc: Optimize emulation of vclzd instruction

[Stefan Brankovic <stefan.brankovic@rt-rk.com>]

Optimize Altivec instruction vclzd (Vector Count Leading Zeros Doubleword).
This instruction counts the number of leading zeros of each doubleword element
in source register and places result in the appropriate doubleword element of
destination register.

Using tcg-s count leading zeros instruction two times(once for each
doubleword element of source register vB) and placing result in
appropriate doubleword element of destination register vD.

Signed-off-by: Stefan Brankovic <stefan.brankovic@rt-rk.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/ppc/helper.h                 |  1 -
 target/ppc/int_helper.c             |  3 ---
 target/ppc/translate/vmx-impl.inc.c | 28 +++++++++++++++++++++++++++-
 3 files changed, 27 insertions(+), 5 deletions(-)

diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index 0aa1e05..3b92e3b 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -306,7 +306,6 @@ DEF_HELPER_4(vctsxs, void, env, avr, avr, i32)
 DEF_HELPER_2(vclzb, void, avr, avr)
 DEF_HELPER_2(vclzh, void, avr, avr)
 DEF_HELPER_2(vclzw, void, avr, avr)
-DEF_HELPER_2(vclzd, void, avr, avr)
 DEF_HELPER_2(vctzb, void, avr, avr)
 DEF_HELPER_2(vctzh, void, avr, avr)
 DEF_HELPER_2(vctzw, void, avr, avr)
diff --git a/target/ppc/int_helper.c b/target/ppc/int_helper.c
index 1e32549..3134798 100644
--- a/target/ppc/int_helper.c
+++ b/target/ppc/int_helper.c
@@ -1803,17 +1803,14 @@ VUPK(lsw, s64, s32, UPKLO)
 #define clzb(v) ((v) ? clz32((uint32_t)(v) << 24) : 8)
 #define clzh(v) ((v) ? clz32((uint32_t)(v) << 16) : 16)
 #define clzw(v) clz32((v))
-#define clzd(v) clz64((v))
 
 VGENERIC_DO(clzb, u8)
 VGENERIC_DO(clzh, u16)
 VGENERIC_DO(clzw, u32)
-VGENERIC_DO(clzd, u64)
 
 #undef clzb
 #undef clzh
 #undef clzw
-#undef clzd
 
 #define ctzb(v) ((v) ? ctz32(v) : 8)
 #define ctzh(v) ((v) ? ctz32(v) : 16)
diff --git a/target/ppc/translate/vmx-impl.inc.c b/target/ppc/translate/vmx-impl.inc.c
index a3467a5..c5bebfb 100644
--- a/target/ppc/translate/vmx-impl.inc.c
+++ b/target/ppc/translate/vmx-impl.inc.c
@@ -830,6 +830,32 @@ static void trans_vgbbd(DisasContext *ctx)
     tcg_temp_free_i64(avr[1]);
 }
 
+/*
+ * vclzd VRT,VRB - Vector Count Leading Zeros Doubleword
+ *
+ * Counting the number of leading zero bits of each doubleword element in source
+ * register and placing result in appropriate doubleword element of destination
+ * register.
+ */
+static void trans_vclzd(DisasContext *ctx)
+{
+    int VT = rD(ctx->opcode);
+    int VB = rB(ctx->opcode);
+    TCGv_i64 avr = tcg_temp_new_i64();
+
+    /* high doubleword */
+    get_avr64(avr, VB, true);
+    tcg_gen_clzi_i64(avr, avr, 64);
+    set_avr64(VT, avr, true);
+
+    /* low doubleword */
+    get_avr64(avr, VB, false);
+    tcg_gen_clzi_i64(avr, avr, 64);
+    set_avr64(VT, avr, false);
+
+    tcg_temp_free_i64(avr);
+}
+
 GEN_VXFORM(vmuloub, 4, 0);
 GEN_VXFORM(vmulouh, 4, 1);
 GEN_VXFORM(vmulouw, 4, 2);
@@ -1346,7 +1372,7 @@ GEN_VAFORM_PAIRED(vmaddfp, vnmsubfp, 23)
 GEN_VXFORM_NOA(vclzb, 1, 28)
 GEN_VXFORM_NOA(vclzh, 1, 29)
 GEN_VXFORM_NOA(vclzw, 1, 30)
-GEN_VXFORM_NOA(vclzd, 1, 31)
+GEN_VXFORM_TRANS(vclzd, 1, 31)
 GEN_VXFORM_NOA_2(vnegw, 1, 24, 6)
 GEN_VXFORM_NOA_2(vnegd, 1, 24, 7)
 GEN_VXFORM_NOA_2(vextsb2w, 1, 24, 16)
-- 
2.7.4