[Qemu-devel] [PATCH v3 3/8] target/ppc: Optimize emulation of vpkpx instruction

[Stefan Brankovic]

Optimize altivec instruction vpkpx (Vector Pack Pixel).
Rearranges 8 pixels coded in 6-5-5 pattern (4 from each source register)
into contigous array of bits in the destination register.

In each iteration of outer loop, the instruction is to be done with
the 6-5-5 pack for 2 pixels of each doubleword element of each
source register. The first thing to be done in outer loop is
choosing which doubleword element of which register is to be used
in current iteration and it is to be placed in avr variable. The
next step is to perform 6-5-5 pack of pixels on avr variable in inner
for loop(2 iterations, 1 for each pixel) and save result in tmp variable.
In the end of outer for loop, the result is merged in variable called
result and saved in appropriate doubleword element of vD if the whole
doubleword is finished(every second iteration). The outer loop has 4
iterations.

Signed-off-by: Stefan Brankovic <address@hidden>
---
 target/ppc/helper.h                 |  1 -
 target/ppc/int_helper.c             | 21 ---------
 target/ppc/translate/vmx-impl.inc.c | 93 ++++++++++++++++++++++++++++++++++++-
 3 files changed, 92 insertions(+), 23 deletions(-)

diff --git a/target/ppc/helper.h b/target/ppc/helper.h
index 33dad6a..7a3d68d 100644
--- a/target/ppc/helper.h
+++ b/target/ppc/helper.h
@@ -254,7 +254,6 @@ DEF_HELPER_4(vpkudus, void, env, avr, avr, avr)
 DEF_HELPER_4(vpkuhum, void, env, avr, avr, avr)
 DEF_HELPER_4(vpkuwum, void, env, avr, avr, avr)
 DEF_HELPER_4(vpkudum, void, env, avr, avr, avr)
-DEF_HELPER_3(vpkpx, void, avr, avr, avr)
 DEF_HELPER_5(vmhaddshs, void, env, avr, avr, avr, avr)
 DEF_HELPER_5(vmhraddshs, void, env, avr, avr, avr, avr)
 DEF_HELPER_5(vmsumuhm, void, env, avr, avr, avr, avr)
diff --git a/target/ppc/int_helper.c b/target/ppc/int_helper.c
index a23853e..f397380 100644
--- a/target/ppc/int_helper.c
+++ b/target/ppc/int_helper.c
@@ -1536,27 +1536,6 @@ void helper_vpmsumd(ppc_avr_t *r, ppc_avr_t *a, 
ppc_avr_t *b)
 #else
 #define PKBIG 0
 #endif
-void helper_vpkpx(ppc_avr_t *r, ppc_avr_t *a, ppc_avr_t *b)
-{
-    int i, j;
-    ppc_avr_t result;
-#if defined(HOST_WORDS_BIGENDIAN)
-    const ppc_avr_t *x[2] = { a, b };
-#else
-    const ppc_avr_t *x[2] = { b, a };
-#endif
-
-    VECTOR_FOR_INORDER_I(i, u64) {
-        VECTOR_FOR_INORDER_I(j, u32) {
-            uint32_t e = x[i]->u32[j];
-
-            result.u16[4 * i + j] = (((e >> 9) & 0xfc00) |
-                                     ((e >> 6) & 0x3e0) |
-                                     ((e >> 3) & 0x1f));
-        }
-    }
-    *r = result;
-}
 
 #define VPK(suffix, from, to, cvt, dosat)                               \
     void helper_vpk##suffix(CPUPPCState *env, ppc_avr_t *r,             \
diff --git a/target/ppc/translate/vmx-impl.inc.c 
b/target/ppc/translate/vmx-impl.inc.c
index cc11d21..30dd7e1 100644
--- a/target/ppc/translate/vmx-impl.inc.c
+++ b/target/ppc/translate/vmx-impl.inc.c
@@ -579,6 +579,97 @@ static void trans_lvsr(DisasContext *ctx)
 }
 
 /*
+ * vpkpx VRT,VRA,VRB - Vector Pack Pixel
+ *
+ * Rearranges 8 pixels coded in 6-5-5 pattern (4 from each source register)
+ * into contigous array of bits in the destination register.
+ */
+static void trans_vpkpx(DisasContext *ctx)
+{
+    int VT = rD(ctx->opcode);
+    int VA = rA(ctx->opcode);
+    int VB = rB(ctx->opcode);
+    TCGv_i64 tmp = tcg_temp_new_i64();
+    TCGv_i64 shifted = tcg_temp_new_i64();
+    TCGv_i64 avr = tcg_temp_new_i64();
+    TCGv_i64 result = tcg_temp_new_i64();
+    int64_t mask1 = 0x1fULL;
+    int64_t mask2 = 0x1fULL << 5;
+    int64_t mask3 = 0x3fULL << 10;
+    int i, j;
+    /*
+     * In each iteration do the 6-5-5 pack for 2 pixels of each doubleword
+     * element of each source register.
+     */
+    for (i = 0; i < 4; i++) {
+        switch (i) {
+        case 0:
+            /*
+             * Get high doubleword of vA to perfrom 6-5-5 pack of pixels
+             * 1 and 2.
+             */
+            get_avr64(avr, VA, true);
+            tcg_gen_movi_i64(result, 0x0ULL);
+            break;
+        case 1:
+            /*
+             * Get low doubleword of vA to perfrom 6-5-5 pack of pixels
+             * 3 and 4.
+             */
+            get_avr64(avr, VA, false);
+            break;
+        case 2:
+            /*
+             * Get high doubleword of vB to perfrom 6-5-5 pack of pixels
+             * 5 and 6.
+             */
+            get_avr64(avr, VB, true);
+            tcg_gen_movi_i64(result, 0x0ULL);
+            break;
+        case 3:
+            /*
+             * Get low doubleword of vB to perfrom 6-5-5 pack of pixels
+             * 7 and 8.
+             */
+            get_avr64(avr, VB, false);
+            break;
+        }
+        /* Perform the packing for 2 pixels(each iteration for 1). */
+        tcg_gen_movi_i64(tmp, 0x0ULL);
+        for (j = 0; j < 2; j++) {
+            tcg_gen_shri_i64(shifted, avr, (j * 16 + 3));
+            tcg_gen_andi_i64(shifted, shifted, mask1 << (j * 16));
+            tcg_gen_or_i64(tmp, tmp, shifted);
+
+            tcg_gen_shri_i64(shifted, avr, (j * 16 + 6));
+            tcg_gen_andi_i64(shifted, shifted, mask2 << (j * 16));
+            tcg_gen_or_i64(tmp, tmp, shifted);
+
+            tcg_gen_shri_i64(shifted, avr, (j * 16 + 9));
+            tcg_gen_andi_i64(shifted, shifted, mask3 << (j * 16));
+            tcg_gen_or_i64(tmp, tmp, shifted);
+        }
+        if ((i == 0) || (i == 2)) {
+            tcg_gen_shli_i64(tmp, tmp, 32);
+        }
+        tcg_gen_or_i64(result, result, tmp);
+        if (i == 1) {
+            /* Place packed pixels 1:4 to high doubleword of vD. */
+            set_avr64(VT, result, true);
+        }
+        if (i == 3) {
+            /* Place packed pixels 5:8 to low doubleword of vD. */
+            set_avr64(VT, result, false);
+        }
+    }
+
+    tcg_temp_free_i64(tmp);
+    tcg_temp_free_i64(shifted);
+    tcg_temp_free_i64(avr);
+    tcg_temp_free_i64(result);
+}
+
+/*
  * vsl VRT,VRA,VRB - Vector Shift Left
  *
  * Shifting left 128 bit value of vA by value specified in bits 125-127 of vB.
@@ -802,7 +893,7 @@ GEN_VXFORM_ENV(vpksdus, 7, 21);
 GEN_VXFORM_ENV(vpkshss, 7, 6);
 GEN_VXFORM_ENV(vpkswss, 7, 7);
 GEN_VXFORM_ENV(vpksdss, 7, 23);
-GEN_VXFORM(vpkpx, 7, 12);
+GEN_VXFORM_TRANS(vpkpx, 7, 12);
 GEN_VXFORM_ENV(vsum4ubs, 4, 24);
 GEN_VXFORM_ENV(vsum4sbs, 4, 28);
 GEN_VXFORM_ENV(vsum4shs, 4, 25);
-- 
2.7.4