avcodec/mips: [loongson] reoptimize simple idct with mmi.

Performance of mpeg4 decoding improved about 23%(from 128fps to 158fps, tested on loongson 3A3000).
Reoptimized following functions with mmi.
1. ff_simple_idct_put_8_mmi
2. ff_simple_idct_add_8_mmi
3. ff_simple_idct_8_mmi
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/mips/idctdsp_init_mips.c

@@ -20,6 +20,7 @@
  */
 
 #include "idctdsp_mips.h"
+#include "xvididct_mips.h"
 
 #if HAVE_MSA
 static av_cold void idctdsp_init_msa(IDCTDSPContext *c, AVCodecContext *avctx,
@@ -48,8 +49,10 @@ static av_cold void idctdsp_init_mmi(IDCTDSPContext *c, AVCodecContext *avctx,
     if ((avctx->lowres != 1) && (avctx->lowres != 2) && (avctx->lowres != 3) &&
         (avctx->bits_per_raw_sample != 10) &&
         (avctx->bits_per_raw_sample != 12) &&
-        (avctx->idct_algo == FF_IDCT_AUTO)) {
-                c->idct = ff_simple_idct_mmi;
+        ((avctx->idct_algo == FF_IDCT_AUTO) || (avctx->idct_algo == FF_IDCT_SIMPLE))) {
+                c->idct_put = ff_simple_idct_put_8_mmi;
+                c->idct_add = ff_simple_idct_add_8_mmi;
+                c->idct = ff_simple_idct_8_mmi;
                 c->perm_type = FF_IDCT_PERM_NONE;
     }
 

libavcodec/mips/idctdsp_mips.h

@@ -46,8 +46,8 @@ void ff_put_signed_pixels_clamped_mmi(const int16_t *block,
         uint8_t *av_restrict pixels, ptrdiff_t line_size);
 void ff_add_pixels_clamped_mmi(const int16_t *block,
         uint8_t *av_restrict pixels, ptrdiff_t line_size);
-void ff_simple_idct_mmi(int16_t *block);
-void ff_simple_idct_put_mmi(uint8_t *dest, ptrdiff_t line_size, int16_t *block);
-void ff_simple_idct_add_mmi(uint8_t *dest, ptrdiff_t line_size, int16_t *block);
+void ff_simple_idct_8_mmi(int16_t *block);
+void ff_simple_idct_put_8_mmi(uint8_t *dest, ptrdiff_t line_size, int16_t *block);
+void ff_simple_idct_add_8_mmi(uint8_t *dest, ptrdiff_t line_size, int16_t *block);
 
 #endif  // #ifndef AVCODEC_MIPS_IDCTDSP_MIPS_H

libavutil/mips/mmiutils.h

@@ -201,6 +201,55 @@
 
 #endif /* HAVE_LOONGSON2 */
 
+/**
+ * backup register
+ */
+#define BACKUP_REG \
+  double temp_backup_reg[8];                                    \
+  if (_MIPS_SIM == _ABI64)                                      \
+    __asm__ volatile (                                          \
+      "gssqc1       $f25,      $f24,       0x00(%[temp])  \n\t" \
+      "gssqc1       $f27,      $f26,       0x10(%[temp])  \n\t" \
+      "gssqc1       $f29,      $f28,       0x20(%[temp])  \n\t" \
+      "gssqc1       $f31,      $f30,       0x30(%[temp])  \n\t" \
+      :                                                         \
+      : [temp]"r"(temp_backup_reg)                              \
+      : "memory"                                                \
+    );                                                          \
+  else                                                          \
+    __asm__ volatile (                                          \
+      "gssqc1       $f22,      $f20,       0x00(%[temp])  \n\t" \
+      "gssqc1       $f26,      $f24,       0x10(%[temp])  \n\t" \
+      "gssqc1       $f30,      $f28,       0x20(%[temp])  \n\t" \
+      :                                                         \
+      : [temp]"r"(temp_backup_reg)                              \
+      : "memory"                                                \
+    );
+
+/**
+ * recover register
+ */
+#define RECOVER_REG \
+  if (_MIPS_SIM == _ABI64)                                      \
+    __asm__ volatile (                                          \
+      "gslqc1       $f25,      $f24,       0x00(%[temp])  \n\t" \
+      "gslqc1       $f27,      $f26,       0x10(%[temp])  \n\t" \
+      "gslqc1       $f29,      $f28,       0x20(%[temp])  \n\t" \
+      "gslqc1       $f31,      $f30,       0x30(%[temp])  \n\t" \
+      :                                                         \
+      : [temp]"r"(temp_backup_reg)                              \
+      : "memory"                                                \
+    );                                                          \
+  else                                                          \
+    __asm__ volatile (                                          \
+      "gslqc1       $f22,      $f20,       0x00(%[temp])  \n\t" \
+      "gslqc1       $f26,      $f24,       0x10(%[temp])  \n\t" \
+      "gslqc1       $f30,      $f28,       0x20(%[temp])  \n\t" \
+      :                                                         \
+      : [temp]"r"(temp_backup_reg)                              \
+      : "memory"                                                \
+    );
+
 #define TRANSPOSE_4H(m1, m2, m3, m4, t1, t2, t3, t4, t5, r1, zero, shift) \
         "li         "#r1",  0x93                                    \n\t" \
         "xor        "#zero","#zero","#zero"                         \n\t" \