From: Keith Whitwell <keith@tungstengraphics.com>
Date: Fri, 2 May 2008 14:02:18 +0000 (+0200)
Subject: tgsi: Implement fast rsqrtf. Not tested, inactive.
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=17058e07469f2dc5b47b4f820bd5a31b7ed9177c;p=mesa.git

tgsi: Implement fast rsqrtf. Not tested, inactive.
---

diff --git a/src/gallium/auxiliary/tgsi/exec/tgsi_exec.c b/src/gallium/auxiliary/tgsi/exec/tgsi_exec.c
index 5d5125f7cbe..826b432f09e 100644
--- a/src/gallium/auxiliary/tgsi/exec/tgsi_exec.c
+++ b/src/gallium/auxiliary/tgsi/exec/tgsi_exec.c
@@ -88,6 +88,10 @@
 #define TEMP_OUTPUT_C      TGSI_EXEC_TEMP_OUTPUT_C
 #define TEMP_PRIMITIVE_I   TGSI_EXEC_TEMP_PRIMITIVE_I
 #define TEMP_PRIMITIVE_C   TGSI_EXEC_TEMP_PRIMITIVE_C
+#define TEMP_3_I           TGSI_EXEC_TEMP_THREE_I
+#define TEMP_3_C           TGSI_EXEC_TEMP_THREE_C
+#define TEMP_HALF_I        TGSI_EXEC_TEMP_HALF_I
+#define TEMP_HALF_C        TGSI_EXEC_TEMP_HALF_C
 #define TEMP_R0            TGSI_EXEC_TEMP_R0
 
 #define FOR_EACH_CHANNEL(CHAN)\
@@ -262,6 +266,8 @@ tgsi_exec_machine_init(
       mach->Temps[TEMP_2_I].xyzw[TEMP_2_C].f[i] = 2.0f;
       mach->Temps[TEMP_128_I].xyzw[TEMP_128_C].f[i] = 128.0f;
       mach->Temps[TEMP_M128_I].xyzw[TEMP_M128_C].f[i] = -128.0f;
+      mach->Temps[TEMP_3_I].xyzw[TEMP_3_C].f[i] = 3.0f;
+      mach->Temps[TEMP_HALF_I].xyzw[TEMP_HALF_C].f[i] = 0.5f;
    }
 }
 
diff --git a/src/gallium/auxiliary/tgsi/exec/tgsi_exec.h b/src/gallium/auxiliary/tgsi/exec/tgsi_exec.h
index 92e2e5e9859..19bd78df3d3 100644
--- a/src/gallium/auxiliary/tgsi/exec/tgsi_exec.h
+++ b/src/gallium/auxiliary/tgsi/exec/tgsi_exec.h
@@ -133,9 +133,15 @@ struct tgsi_exec_labels
 #define TGSI_EXEC_TEMP_PRIMITIVE_I  34
 #define TGSI_EXEC_TEMP_PRIMITIVE_C  2
 
-#define TGSI_EXEC_TEMP_R0           35
+#define TGSI_EXEC_TEMP_THREE_I      34
+#define TGSI_EXEC_TEMP_THREE_C      3
 
-#define TGSI_EXEC_NUM_TEMPS   (32 + 4)
+#define TGSI_EXEC_TEMP_HALF_I       35
+#define TGSI_EXEC_TEMP_HALF_C       0
+
+#define TGSI_EXEC_TEMP_R0           36
+
+#define TGSI_EXEC_NUM_TEMPS   (32 + 5)
 #define TGSI_EXEC_NUM_ADDRS   1
 #define TGSI_EXEC_NUM_IMMEDIATES  256
 
diff --git a/src/gallium/auxiliary/tgsi/exec/tgsi_sse2.c b/src/gallium/auxiliary/tgsi/exec/tgsi_sse2.c
index 2fd76a3072d..dbf002130bb 100755
--- a/src/gallium/auxiliary/tgsi/exec/tgsi_sse2.c
+++ b/src/gallium/auxiliary/tgsi/exec/tgsi_sse2.c
@@ -36,7 +36,11 @@
 
 #ifdef PIPE_ARCH_X86
 
-#define HIGH_PRECISION 1  /* for 1/sqrt() */
+/* for 1/sqrt() 
+ * 
+ * This costs about 100fps (close to 10%) in gears:
+ */
+#define HIGH_PRECISION 1  
 
 
 #define FOR_EACH_CHANNEL( CHAN )\
@@ -794,20 +798,25 @@ emit_rsqrt(
     *
     * See: http://softwarecommunity.intel.com/articles/eng/1818.htm
     */
-   /* This is some code that woudl do the above for a scalar 'a'.  We
-    * obviously are interested in a vector version:
-    *
-    * movss   xmm3, a;
-    * movss   xmm1, half;
-    * movss   xmm2, three;
-    * rsqrtss xmm0, xmm3;
-    * mulss   xmm3, xmm0;
-    * mulss   xmm1, xmm0;
-    * mulss   xmm3, xmm0;
-    * subss   xmm2, xmm3;
-    * mulss   xmm1, xmm2;
-    * movss   x,    xmm1;
-    */
+   {
+      struct x86_reg dst = make_xmm( xmm_dst );
+      struct x86_reg src = make_xmm( xmm_src );
+      struct x86_reg tmp0 = make_xmm( 2 );
+      struct x86_reg tmp1 = make_xmm( 3 );
+
+      assert( xmm_dst != xmm_src );
+      assert( xmm_dst != 2 && xmm_dst != 3 );
+      assert( xmm_src != 2 && xmm_src != 3 );
+
+      sse_movaps(  func, dst,  get_temp( TGSI_EXEC_TEMP_HALF_I, TGSI_EXEC_TEMP_HALF_C ) );
+      sse_movaps(  func, tmp0, get_temp( TGSI_EXEC_TEMP_THREE_I, TGSI_EXEC_TEMP_THREE_C ) );
+      sse_rsqrtps( func, tmp1, src  );
+      sse_mulps(   func, src,  tmp1 );
+      sse_mulps(   func, dst,  tmp1 );
+      sse_mulps(   func, src,  tmp1 );
+      sse_subps(   func, tmp0, src  );
+      sse_mulps(   func, dst,  tmp0 );
+   }
 #endif
 #else
    /* On Intel CPUs at least, this is only accurate to 12 bits -- not
@@ -1295,9 +1304,9 @@ emit_instruction(
    case TGSI_OPCODE_RSQ:
    /* TGSI_OPCODE_RECIPSQRT */
       FETCH( func, *inst, 0, 0, CHAN_X );
-      emit_rsqrt( func, 0, 0 );
+      emit_rsqrt( func, 1, 0 );
       FOR_EACH_DST0_ENABLED_CHANNEL( *inst, chan_index ) {
-         STORE( func, *inst, 0, 0, chan_index );
+         STORE( func, *inst, 1, 0, chan_index );
       }
       break;