additional optimizations for POWER9 (#454)

Makefile

@@ -156,7 +156,8 @@ endif
 ifneq ($(filter ppc64%,$(UNAME_M)),)
 	POWER9_M := $(shell grep "POWER9" /proc/cpuinfo)
 	ifneq (,$(findstring POWER9,$(POWER9_M)))
-		CFLAGS += -mpower9-vector
+		CFLAGS += -mcpu=power9
+		CXXFLAGS += -mcpu=power9
 	endif
 	# Require c++23's std::byteswap for big-endian support.
 	ifeq ($(UNAME_M),ppc64)

ggml.c

@@ -175,6 +175,39 @@ typedef double ggml_float;
 #define GGML_COMPUTE_FP16_TO_FP32(x) _cvtsh_ss(x)
 #define GGML_COMPUTE_FP32_TO_FP16(x) _cvtss_sh(x, 0)
 
+#elif defined(__POWER9_VECTOR__)
+
+#define GGML_COMPUTE_FP16_TO_FP32(x) ggml_compute_fp16_to_fp32(x)
+#define GGML_COMPUTE_FP32_TO_FP16(x) ggml_compute_fp32_to_fp16(x)
+/* the inline asm below is about 12% faster than the lookup method */
+#define GGML_FP16_TO_FP32(x) GGML_COMPUTE_FP16_TO_FP32(x)
+#define GGML_FP32_TO_FP16(x) GGML_COMPUTE_FP32_TO_FP16(x)
+
+static inline float ggml_compute_fp16_to_fp32(ggml_fp16_t h) {
+    register float f;
+    register double d;
+    __asm__(
+        "mtfprd %0,%2\n"
+        "xscvhpdp %0,%0\n"
+        "frsp %1,%0\n" :
+        /* temp */ "=d"(d),
+        /* out */  "=f"(f):
+        /* in */   "r"(h));
+    return f;
+}
+
+static inline ggml_fp16_t ggml_compute_fp32_to_fp16(float f) {
+    register double d;
+    register ggml_fp16_t r;
+    __asm__( /* xscvdphp can work on double or single precision */
+        "xscvdphp %0,%2\n"
+        "mffprd %1,%0\n" :
+        /* temp */ "=d"(d),
+        /* out */  "=r"(r):
+        /* in */   "f"(f));
+    return r;
+}
+
 #else
 
 // FP16 <-> FP32
@@ -272,6 +305,7 @@ static float table_f32_f16[1 << 16];
 
 // On ARM NEON, it's quicker to directly convert x -> x instead of calling into ggml_lookup_fp16_to_fp32,
 // so we define GGML_FP16_TO_FP32 and GGML_FP32_TO_FP16 elsewhere for NEON.
+// This is also true for POWER9.
 #if !defined(GGML_FP16_TO_FP32) || !defined(GGML_FP32_TO_FP16)
 
 inline static float ggml_lookup_fp16_to_fp32(ggml_fp16_t f) {
@@ -462,7 +496,7 @@ static void quantize_row_q4_0_reference(const float * restrict x, void * restric
 void quantize_row_q4_0(const float * restrict x, void * restrict y, int k) {
     assert(k % QK == 0);
 
-#if __ARM_NEON || defined(__AVX2__) || defined(__wasm_simd128__)
+#if __ARM_NEON || defined(__AVX2__) || defined(__wasm_simd128__) || defined(__POWER9_VECTOR__)
     const int nb = k / QK;
     const size_t bs = sizeof(float) + QK/2;
 
@@ -472,7 +506,52 @@ void quantize_row_q4_0(const float * restrict x, void * restrict y, int k) {
     uint8_t pp[QK/2];
 #endif
 
-#if __ARM_NEON
+#if defined(__POWER9_VECTOR__)
+#if QK == 32
+    const vector float v85 = vec_splats(8.5f);
+    for (int i = 0; i < nb; i++) {
+        float amax = 0.0f; // absolute max
+
+        vector float srcv [8];
+        vector float asrcv[8];
+        vector float amaxv[8];
+
+        for (int l = 0; l < 8; l++) srcv[l]  = *(vector float *)(x + i*32 + 4*l);
+        for (int l = 0; l < 8; l++) asrcv[l] = vec_abs(srcv[l]);
+
+        for (int l = 0; l < 4; l++) amaxv[2*l] = vec_max(asrcv[2*l], asrcv[2*l+1]);
+        //for (int l = 0; l < 2; l++) amaxv[4*l] = vec_max(amaxv[4*l], amaxv[4*l+2]);
+        amaxv[0] = vec_max(amaxv[0], amaxv[2]);
+        amaxv[4] = vec_max(amaxv[4], amaxv[6]);
+        //for (int l = 0; l < 1; l++) amaxv[8*l] = vec_max(amaxv[8*l], amaxv[8*l+4]);
+        amaxv[0] = vec_max(amaxv[0], amaxv[4]);
+
+        amax = MAX(
+                MAX(vec_extract(amaxv[0], 0), vec_extract(amaxv[0], 1)),
+                MAX(vec_extract(amaxv[0], 2), vec_extract(amaxv[0], 3)));
+
+        const float d = amax / ((1 << 3) - 1);
+        const float id = d ? 1.0/d : 0.0;
+
+        *(float *)pd = d;
+        pd += bs;
+
+        const vector float vid = vec_splats(id);
+        for (int l = 0; l < 8; l++) {
+            const vector float vf  = vec_madd(srcv[l], vid, v85);
+            const vector signed int vi = vec_signed(vf);
+
+            pb[2*l + 0] = vec_extract(vi, 0) | (vec_extract(vi, 1) << 4);
+            pb[2*l + 1] = vec_extract(vi, 2) | (vec_extract(vi, 3) << 4);
+        }
+
+        //memcpy(pb, pp, sizeof(pp));
+        pb += bs;
+    }
+#else
+#error "not implemented for QK"
+#endif
+#elif __ARM_NEON
 #if QK == 32
     for (int i = 0; i < nb; i++) {
         float amax = 0.0f; // absolute max