target/ppc: Optimize emulation of vclzw instruction

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

Counting is to be performed in four iterations of for loop(one for each
word elemnt of source register vB). Every iteration consists of loading
appropriate word element from source register, counting leading zeros
with tcg_gen_clzi_i32, and saving the result in appropriate word element
of destination register.

Signed-off-by: Stefan Brankovic <stefan.brankovic@rt-rk.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <1563200574-11098-7-git-send-email-stefan.brankovic@rt-rk.com>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index e203f76bf119273cb091652ffb3bb3e03a7a9e7d..54ea9b95004528b5f589c843f76591ec724f0f43 100644 (file)
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -310,7 +310,6 @@ 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(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 b82765db3360681fffb7334ab3fde0e7c2168e82..46deb57a34369309574a044b97bea765e757f209 100644 (file)
--- a/target/ppc/int_helper.c
+++ b/target/ppc/int_helper.c
@@ -1819,15 +1819,12 @@ 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))
 
 VGENERIC_DO(clzb, u8)
 VGENERIC_DO(clzh, u16)
-VGENERIC_DO(clzw, u32)
 
 #undef clzb
 #undef clzh
-#undef clzw
 
 #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 3372c2c3d38dc0d98078cda2721ca95937dc9c44..0d71c10428603bff1ee8538bc17928d366d5cf3a 100644 (file)
--- a/target/ppc/translate/vmx-impl.inc.c
+++ b/target/ppc/translate/vmx-impl.inc.c
@@ -742,6 +742,32 @@ static void trans_vgbbd(DisasContext *ctx)
     tcg_temp_free_i64(avr[1]);
 }
 
+/*
+ * vclzw VRT,VRB - Vector Count Leading Zeros Word
+ *
+ * Counting the number of leading zero bits of each word element in source
+ * register and placing result in appropriate word element of destination
+ * register.
+ */
+static void trans_vclzw(DisasContext *ctx)
+{
+    int VT = rD(ctx->opcode);
+    int VB = rB(ctx->opcode);
+    TCGv_i32 tmp = tcg_temp_new_i32();
+    int i;
+
+    /* Perform count for every word element using tcg_gen_clzi_i32. */
+    for (i = 0; i < 4; i++) {
+        tcg_gen_ld_i32(tmp, cpu_env,
+            offsetof(CPUPPCState, vsr[32 + VB].u64[0]) + i * 4);
+        tcg_gen_clzi_i32(tmp, tmp, 32);
+        tcg_gen_st_i32(tmp, cpu_env,
+            offsetof(CPUPPCState, vsr[32 + VT].u64[0]) + i * 4);
+    }
+
+    tcg_temp_free_i32(tmp);
+}
+
 /*
  * vclzd VRT,VRB - Vector Count Leading Zeros Doubleword
  *
@@ -1283,7 +1309,7 @@ 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_TRANS(vclzw, 1, 30)
 GEN_VXFORM_TRANS(vclzd, 1, 31)
 GEN_VXFORM_NOA_2(vnegw, 1, 24, 6)
 GEN_VXFORM_NOA_2(vnegd, 1, 24, 7)