COMPMID-896: Replace legacy 4x4 u8 GEMM kernel with safe version.

It's not safe to accumulate two u8xu8 results into a u16 accumulator.
This changes the kernel to use uadalp after every single multiply.
Correct the test fixture as well.

Change-Id: I011b90033c4673e55b843d079e3f7d185b1df330
Reviewed-on: https://eu-gerrit-1.euhpc.arm.com/119096
Tested-by: Jenkins <bsgcomp@arm.com>
Reviewed-by: Georgios Pinitas <georgios.pinitas@arm.com>

2 files changed, 110 insertions, 294 deletions

diff --git a/arm_compute/core/NEON/kernels/assembly/kernels/a64_gemm_u8_4x4/generic.hpp b/arm_compute/core/NEON/kernels/assembly/kernels/a64_gemm_u8_4x4/generic.hpp
index e48c373f21..aff3faf666 100644
--- a/arm_compute/core/NEON/kernels/assembly/kernels/a64_gemm_u8_4x4/generic.hpp
+++ b/arm_compute/core/NEON/kernels/assembly/kernels/a64_gemm_u8_4x4/generic.hpp
@@ -31,7 +31,6 @@ inline void a64_gemm_u8_4x4(const uint8_t *Apanel, const uint8_t *Bpanel, uint32
     const uint8_t *a_ptr = Apanel;
     uint32_t *c_ptr = Cpanel;
     K /= 16;
-    int oddk = (K & 1);
 
     for (int yb=0; yb<ablocks; yb++) {
         const uint8_t *a_ptr0 = a_ptr;
@@ -40,16 +39,12 @@ inline void a64_gemm_u8_4x4(const uint8_t *Apanel, const uint8_t *Bpanel, uint32
         for (int xb=0; xb<bblocks; xb++) {
             a_ptr = a_ptr0;
 
-            int k = ((K+1)/2)-1;
+            int k = K-1;
 
             register uint8x16_t b0  asm("v4");
             register uint8x16_t b1  asm("v5");
             register uint8x16_t b2  asm("v6");
             register uint8x16_t b3  asm("v7");
-            register uint8x16_t b0a asm("v8");
-            register uint8x16_t b1a asm("v9");
-            register uint8x16_t b2a asm("v10");
-            register uint8x16_t b3a asm("v11");
 
             __asm __volatile (
                 "movi	v16.4s, #0x0\n"
@@ -85,377 +80,198 @@ inline void a64_gemm_u8_4x4(const uint8_t *Apanel, const uint8_t *Bpanel, uint32
                 "movi	v31.4s, #0x0\n"
                 ASM_PREFETCH("[%[a_ptr], #256]")
 
-                // Loop structure optimized for A57 (after r0).
-
-                // Unavoidably, the multiply will "dribble" if
-                // dual issued with an add.
-
-                // Minimize the effect of this by making sure
-                // there are 2 adds to run under the dribbled
-                // multiply.
-
-                // Pipeline in blocks of 8 multiplies - combine
-                // this iteration's multiplies with adds from
-                // the previous iteration.
-
-                // So the first block doesn't have any adds to
-                // do - but because all the adds are at the
-                // start of the block it's only the first couple
-                // of multiplies that need to be pulled out.
-
-                // Start of unroll 0 (first iteration)
                 "umull	v12.8h, v0.8b, %[b0].8b\n"
+                "add	%[a_ptr], %[a_ptr], #64\n"
                 "umull	v13.8h, v0.8b, %[b1].8b\n"
+                "umull	v14.8h, v0.8b, %[b2].8b\n"
+                "add	%[b_ptr], %[b_ptr], #64\n"
+                "umull	v15.8h, v0.8b, %[b3].8b\n"
 
                 // Skip loop if we are doing zero iterations of it.
-                "cbz	%w[k], 4f\n"
+                "cbz	%w[k], 2f\n"
 
-                // Unroll 0 continuation (branch target)
                 "1:\n"
-                "umull	v14.8h, v0.8b, %[b2].8b\n"
-                "subs	%w[k], %w[k], #1\n"
-                "umull	v15.8h, v0.8b, %[b3].8b\n"
-                "ldr	%q[b0a], [%[b_ptr], #64]\n"
-                "umlal2	v12.8h, v0.16b, %[b0].16b\n"
-                "umlal2	v13.8h, v0.16b, %[b1].16b\n"
-                "ldr	%q[b1a], [%[b_ptr], #80]\n"
-                "umlal2	v14.8h, v0.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v0.16b, %[b3].16b\n"
-                "ldr 	q0, [%[a_ptr], #64]\n"
+                "uadalp	v16.4s, v12.8h\n"
+                "umull2	v12.8h, v0.16b, %[b0].16b\n"
+                "uadalp	v17.4s, v13.8h\n"
+                "umull2	v13.8h, v0.16b, %[b1].16b\n"
+                "uadalp	v18.4s, v14.8h\n"
+                "umull2	v14.8h, v0.16b, %[b2].16b\n"
+                "uadalp	v19.4s, v15.8h\n"
+                "umull2	v15.8h, v0.16b, %[b3].16b\n"
+                "ldr 	q0, [%[a_ptr]]\n"
 
                 "uadalp	v16.4s, v12.8h\n"
                 "umull	v12.8h, v1.8b, %[b0].8b\n"
                 "uadalp	v17.4s, v13.8h\n"
-                "uadalp	v18.4s, v14.8h\n"
                 "umull	v13.8h, v1.8b, %[b1].8b\n"
-                "uadalp	v19.4s, v15.8h\n"
+                "subs	%w[k], %w[k], #1\n"
+                "uadalp	v18.4s, v14.8h\n"
                 "umull	v14.8h, v1.8b, %[b2].8b\n"
-                "ldr	%q[b2a], [%[b_ptr], #96]\n"
+                "uadalp	v19.4s, v15.8h\n"
                 "umull	v15.8h, v1.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v1.16b, %[b0].16b\n"
-                "ldr	%q[b3a], [%[b_ptr], #112]\n"
-                "umlal2	v13.8h, v1.16b, %[b1].16b\n"
-                "add	%[b_ptr], %[b_ptr], #128\n"
-                "umlal2	v14.8h, v1.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v1.16b, %[b3].16b\n"
-                "ldr 	q1, [%[a_ptr], #80]\n"
 
                 "uadalp	v20.4s, v12.8h\n"
-                "umull	v12.8h, v2.8b, %[b0].8b\n"
+                "umull2	v12.8h, v1.16b, %[b0].16b\n"
                 "uadalp	v21.4s, v13.8h\n"
+                "umull2	v13.8h, v1.16b, %[b1].16b\n"
+                ASM_PREFETCH("[%[a_ptr], #256]")
                 "uadalp	v22.4s, v14.8h\n"
-                "umull	v13.8h, v2.8b, %[b1].8b\n"
+                "umull2	v14.8h, v1.16b, %[b2].16b\n"
                 "uadalp	v23.4s, v15.8h\n"
+                "umull2	v15.8h, v1.16b, %[b3].16b\n"
+                "ldr 	q1, [%[a_ptr], #16]\n"
+
+                "uadalp	v20.4s, v12.8h\n"
+                "umull	v12.8h, v2.8b, %[b0].8b\n"
+                "uadalp	v21.4s, v13.8h\n"
+                "umull	v13.8h, v2.8b, %[b1].8b\n"
+                ASM_PREFETCH("[%[b_ptr], #256]")
+                "uadalp	v22.4s, v14.8h\n"
                 "umull	v14.8h, v2.8b, %[b2].8b\n"
+                "uadalp	v23.4s, v15.8h\n"
                 "umull	v15.8h, v2.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v2.16b, %[b0].16b\n"
-                ASM_PREFETCH("[%[b_ptr], #192]")
-                "umlal2	v13.8h, v2.16b, %[b1].16b\n"
-                "umlal2	v14.8h, v2.16b, %[b2].16b\n"
-                ASM_PREFETCH("[%[a_ptr], #320]")
-                "umlal2	v15.8h, v2.16b, %[b3].16b\n"
-                "ldr 	q2, [%[a_ptr], #96]\n"
 
                 "uadalp	v24.4s, v12.8h\n"
-                "umull	v12.8h, v3.8b, %[b0].8b\n"
+                "umull2	v12.8h, v2.16b, %[b0].16b\n"
                 "uadalp	v25.4s, v13.8h\n"
+                "umull2	v13.8h, v2.16b, %[b1].16b\n"
                 "uadalp	v26.4s, v14.8h\n"
-                "umull	v13.8h, v3.8b, %[b1].8b\n"
+                "umull2	v14.8h, v2.16b, %[b2].16b\n"
                 "uadalp	v27.4s, v15.8h\n"
+                "umull2	v15.8h, v2.16b, %[b3].16b\n"
+                "ldr	q2, [%[a_ptr], #32]\n"
+
+                "uadalp	v24.4s, v12.8h\n"
+                "umull	v12.8h, v3.8b, %[b0].8b\n"
+                "uadalp	v25.4s, v13.8h\n"
+                "umull	v13.8h, v3.8b, %[b1].8b\n"
+                "uadalp	v26.4s, v14.8h\n"
                 "umull	v14.8h, v3.8b, %[b2].8b\n"
+                "uadalp	v27.4s, v15.8h\n"
                 "umull	v15.8h, v3.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v3.16b, %[b0].16b\n"
-                "ldr 	%q[b0], [%[b_ptr], #0]\n"
-                "umlal2	v13.8h, v3.16b, %[b1].16b\n"
-                "umlal2	v14.8h, v3.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v3.16b, %[b3].16b\n"
-                "ldr 	q3, [%[a_ptr], #112]\n"
 
-                // Unroll 1
                 "uadalp	v28.4s, v12.8h\n"
-                "umull	v12.8h, v0.8b, %[b0a].8b\n"
+                "umull2	v12.8h, v3.16b, %[b0].16b\n"
+                "ldr	%q[b0], [%[b_ptr]]\n"
                 "uadalp	v29.4s, v13.8h\n"
+                "umull2	v13.8h, v3.16b, %[b1].16b\n"
+                "ldr	%q[b1], [%[b_ptr], #16]\n"
                 "uadalp	v30.4s, v14.8h\n"
-                "umull	v13.8h, v0.8b, %[b1a].8b\n"
+                "umull2	v14.8h, v3.16b, %[b2].16b\n"
+                "ldr	%q[b2], [%[b_ptr], #32]\n"
                 "uadalp	v31.4s, v15.8h\n"
-                "umull	v14.8h, v0.8b, %[b2a].8b\n"
-                "umull	v15.8h, v0.8b, %[b3a].8b\n"
-                "ldr 	%q[b1], [%[b_ptr], #16]\n"
-                "umlal2	v12.8h, v0.16b, %[b0a].16b\n"
-                "umlal2	v13.8h, v0.16b, %[b1a].16b\n"
-                "ldr 	%q[b2], [%[b_ptr], #32]\n"
-                "umlal2	v14.8h, v0.16b, %[b2a].16b\n"
-                "umlal2	v15.8h, v0.16b, %[b3a].16b\n"
-                "ldr 	q0, [%[a_ptr], #128]\n"
-
-                "uadalp	v16.4s, v12.8h\n"
-                "umull	v12.8h, v1.8b, %[b0a].8b\n"
-                "uadalp	v17.4s, v13.8h\n"
-                "uadalp	v18.4s, v14.8h\n"
-                "umull	v13.8h, v1.8b, %[b1a].8b\n"
-                "uadalp	v19.4s, v15.8h\n"
-                "add	%[a_ptr], %[a_ptr], #128\n"
-                "umull	v14.8h, v1.8b, %[b2a].8b\n"
-                "umull	v15.8h, v1.8b, %[b3a].8b\n"
-                "ldr 	%q[b3], [%[b_ptr], #48]\n"
-                "umlal2	v12.8h, v1.16b, %[b0a].16b\n"
-                "umlal2	v13.8h, v1.16b, %[b1a].16b\n"
-                "umlal2	v14.8h, v1.16b, %[b2a].16b\n"
-                "umlal2	v15.8h, v1.16b, %[b3a].16b\n"
-                "ldr 	q1, [%[a_ptr], #16]\n"
-
-                "uadalp	v20.4s, v12.8h\n"
-                "umull	v12.8h, v2.8b, %[b0a].8b\n"
-                "uadalp	v21.4s, v13.8h\n"
-                "uadalp	v22.4s, v14.8h\n"
-                "umull	v13.8h, v2.8b, %[b1a].8b\n"
-                "uadalp	v23.4s, v15.8h\n"
-                "umull	v14.8h, v2.8b, %[b2a].8b\n"
-                "umull	v15.8h, v2.8b, %[b3a].8b\n"
-                "umlal2	v12.8h, v2.16b, %[b0a].16b\n"
-                ASM_PREFETCH("[%[b_ptr], #256]")
-                "umlal2	v13.8h, v2.16b, %[b1a].16b\n"
-                "umlal2	v14.8h, v2.16b, %[b2a].16b\n"
-                ASM_PREFETCH("[%[a_ptr], #256]")
-                "umlal2	v15.8h, v2.16b, %[b3a].16b\n"
-                "ldr 	q2, [%[a_ptr], #32]\n"
-
-                "uadalp	v24.4s, v12.8h\n"
-                "umull	v12.8h, v3.8b, %[b0a].8b\n"
-                "uadalp	v25.4s, v13.8h\n"
-                "uadalp	v26.4s, v14.8h\n"
-                "umull	v13.8h, v3.8b, %[b1a].8b\n"
-                "uadalp	v27.4s, v15.8h\n"
-                "umull	v14.8h, v3.8b, %[b2a].8b\n"
-                "umull	v15.8h, v3.8b, %[b3a].8b\n"
-                "umlal2	v12.8h, v3.16b, %[b0a].16b\n"
-                "umlal2	v13.8h, v3.16b, %[b1a].16b\n"
-                "umlal2	v14.8h, v3.16b, %[b2a].16b\n"
-                "umlal2	v15.8h, v3.16b, %[b3a].16b\n"
-                "ldr 	q3, [%[a_ptr], #48]\n"
+                "umull2	v15.8h, v3.16b, %[b3].16b\n"
+                "ldr	%q[b3], [%[b_ptr], #48]\n"
 
-                // Start of unroll 0 for next iteration.
                 "uadalp	v28.4s, v12.8h\n"
                 "umull	v12.8h, v0.8b, %[b0].8b\n"
+                "add	%[b_ptr], %[b_ptr], #64\n"
                 "uadalp	v29.4s, v13.8h\n"
-                "uadalp	v30.4s, v14.8h\n"
                 "umull	v13.8h, v0.8b, %[b1].8b\n"
+                "ldr	q3, [%[a_ptr], #48]\n"
+                "uadalp	v30.4s, v14.8h\n"
+                "umull	v14.8h, v0.8b, %[b2].8b\n"
+                "add	%[a_ptr], %[a_ptr], #64\n"
                 "uadalp	v31.4s, v15.8h\n"
+                "umull	v15.8h, v0.8b, %[b3].8b\n"
                 "bne	1b\n"
 
-                // Target to use when K=1 or 2 (i.e. zero iterations of main loop)
-                "4:\n"
-
-                // Branch to alternative tail for odd K
-                "cbnz	%w[oddk], 2f\n"
-
-                // Detached final iteration (even K)
-                "umull	v14.8h, v0.8b, %[b2].8b\n"
-                "umull	v15.8h, v0.8b, %[b3].8b\n"
-                "ldr	%q[b0a], [%[b_ptr], #64]\n"
-                "umlal2	v12.8h, v0.16b, %[b0].16b\n"
-                "umlal2	v13.8h, v0.16b, %[b1].16b\n"
-                "ldr	%q[b1a], [%[b_ptr], #80]\n"
-                "umlal2	v14.8h, v0.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v0.16b, %[b3].16b\n"
-                "ldr 	q0, [%[a_ptr], #64]\n"
+                // Branch target
+                "2:\n"
+                "uadalp	v16.4s, v12.8h\n"
+                "umull2	v12.8h, v0.16b, %[b0].16b\n"
+                "uadalp	v17.4s, v13.8h\n"
+                "umull2	v13.8h, v0.16b, %[b1].16b\n"
+                "uadalp	v18.4s, v14.8h\n"
+                "umull2	v14.8h, v0.16b, %[b2].16b\n"
+                "uadalp	v19.4s, v15.8h\n"
+                "umull2	v15.8h, v0.16b, %[b3].16b\n"
 
                 "uadalp	v16.4s, v12.8h\n"
                 "umull	v12.8h, v1.8b, %[b0].8b\n"
                 "uadalp	v17.4s, v13.8h\n"
-                "uadalp	v18.4s, v14.8h\n"
                 "umull	v13.8h, v1.8b, %[b1].8b\n"
-                "uadalp	v19.4s, v15.8h\n"
+                "uadalp	v18.4s, v14.8h\n"
                 "umull	v14.8h, v1.8b, %[b2].8b\n"
-                "ldr	%q[b2a], [%[b_ptr], #96]\n"
+                "uadalp	v19.4s, v15.8h\n"
                 "umull	v15.8h, v1.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v1.16b, %[b0].16b\n"
-                "ldr	%q[b3a], [%[b_ptr], #112]\n"
-                "umlal2	v13.8h, v1.16b, %[b1].16b\n"
-                "add	%[b_ptr], %[b_ptr], #128\n"
-                "umlal2	v14.8h, v1.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v1.16b, %[b3].16b\n"
-                "ldr 	q1, [%[a_ptr], #80]\n"
 
                 "uadalp	v20.4s, v12.8h\n"
-                "umull	v12.8h, v2.8b, %[b0].8b\n"
+                "umull2	v12.8h, v1.16b, %[b0].16b\n"
                 "uadalp	v21.4s, v13.8h\n"
+                "umull2	v13.8h, v1.16b, %[b1].16b\n"
                 "uadalp	v22.4s, v14.8h\n"
-                "umull	v13.8h, v2.8b, %[b1].8b\n"
+                "umull2	v14.8h, v1.16b, %[b2].16b\n"
                 "uadalp	v23.4s, v15.8h\n"
+                "umull2	v15.8h, v1.16b, %[b3].16b\n"
+
+                "uadalp	v20.4s, v12.8h\n"
+                "umull	v12.8h, v2.8b, %[b0].8b\n"
+                "uadalp	v21.4s, v13.8h\n"
+                "umull	v13.8h, v2.8b, %[b1].8b\n"
+                "uadalp	v22.4s, v14.8h\n"
                 "umull	v14.8h, v2.8b, %[b2].8b\n"
+                "uadalp	v23.4s, v15.8h\n"
                 "umull	v15.8h, v2.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v2.16b, %[b0].16b\n"
-                "umlal2	v13.8h, v2.16b, %[b1].16b\n"
-                "umlal2	v14.8h, v2.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v2.16b, %[b3].16b\n"
-                "ldr 	q2, [%[a_ptr], #96]\n"
 
                 "uadalp	v24.4s, v12.8h\n"
-                "umull	v12.8h, v3.8b, %[b0].8b\n"
+                "umull2	v12.8h, v2.16b, %[b0].16b\n"
                 "uadalp	v25.4s, v13.8h\n"
+                "umull2	v13.8h, v2.16b, %[b1].16b\n"
                 "uadalp	v26.4s, v14.8h\n"
-                "umull	v13.8h, v3.8b, %[b1].8b\n"
+                "umull2	v14.8h, v2.16b, %[b2].16b\n"
                 "uadalp	v27.4s, v15.8h\n"
+                "umull2	v15.8h, v2.16b, %[b3].16b\n"
+
+                "uadalp	v24.4s, v12.8h\n"
+                "umull	v12.8h, v3.8b, %[b0].8b\n"
+                "uadalp	v25.4s, v13.8h\n"
+                "umull	v13.8h, v3.8b, %[b1].8b\n"
+                "uadalp	v26.4s, v14.8h\n"
                 "umull	v14.8h, v3.8b, %[b2].8b\n"
+                "uadalp	v27.4s, v15.8h\n"
                 "umull	v15.8h, v3.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v3.16b, %[b0].16b\n"
-                "umlal2	v13.8h, v3.16b, %[b1].16b\n"
-                "umlal2	v14.8h, v3.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v3.16b, %[b3].16b\n"
-                "ldr 	q3, [%[a_ptr], #112]\n"
 
-                // Unroll 1
                 "uadalp	v28.4s, v12.8h\n"
-                "umull	v12.8h, v0.8b, %[b0a].8b\n"
+                "umull2	v12.8h, v3.16b, %[b0].16b\n"
                 "uadalp	v29.4s, v13.8h\n"
+                "umull2	v13.8h, v3.16b, %[b1].16b\n"
                 "uadalp	v30.4s, v14.8h\n"
-                "umull	v13.8h, v0.8b, %[b1a].8b\n"
+                "umull2	v14.8h, v3.16b, %[b2].16b\n"
                 "uadalp	v31.4s, v15.8h\n"
-                "umull	v14.8h, v0.8b, %[b2a].8b\n"
-                "add	%[a_ptr], %[a_ptr], #128\n"
-                "umull	v15.8h, v0.8b, %[b3a].8b\n"
-                "umlal2	v12.8h, v0.16b, %[b0a].16b\n"
-                "umlal2	v13.8h, v0.16b, %[b1a].16b\n"
-                "umlal2	v14.8h, v0.16b, %[b2a].16b\n"
-                "umlal2	v15.8h, v0.16b, %[b3a].16b\n"
+                "umull2	v15.8h, v3.16b, %[b3].16b\n"
 
-                "uadalp	v16.4s, v12.8h\n"
-                "umull	v12.8h, v1.8b, %[b0a].8b\n"
-                "uadalp	v17.4s, v13.8h\n"
-                "uadalp	v18.4s, v14.8h\n"
-                "umull	v13.8h, v1.8b, %[b1a].8b\n"
-                "uadalp	v19.4s, v15.8h\n"
-                "umull	v14.8h, v1.8b, %[b2a].8b\n"
-                "umull	v15.8h, v1.8b, %[b3a].8b\n"
-                "umlal2	v12.8h, v1.16b, %[b0a].16b\n"
-                "addp	v16.4s, v16.4s, v17.4s\n"
-                "umlal2	v13.8h, v1.16b, %[b1a].16b\n"
-                "addp	v17.4s, v18.4s, v19.4s\n"
-                "umlal2	v14.8h, v1.16b, %[b2a].16b\n"
-                "umlal2	v15.8h, v1.16b, %[b3a].16b\n"
+                "uadalp	v28.4s, v12.8h\n"
+                "uadalp	v29.4s, v13.8h\n"
+                "uadalp	v30.4s, v14.8h\n"
+                "uadalp	v31.4s, v15.8h\n"
 
-                "uadalp	v20.4s, v12.8h\n"
-                "umull	v12.8h, v2.8b, %[b0a].8b\n"
-                "uadalp	v21.4s, v13.8h\n"
-                "uadalp	v22.4s, v14.8h\n"
-                "umull	v13.8h, v2.8b, %[b1a].8b\n"
-                "uadalp	v23.4s, v15.8h\n"
                 "addp	v16.4s, v16.4s, v17.4s\n"
-                "umull	v14.8h, v2.8b, %[b2a].8b\n"
+                "addp	v17.4s, v18.4s, v19.4s\n"
                 "addp	v18.4s, v20.4s, v21.4s\n"
                 "addp	v19.4s, v22.4s, v23.4s\n"
-                "umull	v15.8h, v2.8b, %[b3a].8b\n"
-                "umlal2	v12.8h, v2.16b, %[b0a].16b\n"
-                "str	q16, [%[c_ptr]]\n"
-                "umlal2	v13.8h, v2.16b, %[b1a].16b\n"
-                "umlal2	v14.8h, v2.16b, %[b2a].16b\n"
-                "umlal2	v15.8h, v2.16b, %[b3a].16b\n"
-
-                "uadalp	v24.4s, v12.8h\n"
-                "umull	v12.8h, v3.8b, %[b0a].8b\n"
-                "uadalp	v25.4s, v13.8h\n"
-                "uadalp	v26.4s, v14.8h\n"
-                "umull	v13.8h, v3.8b, %[b1a].8b\n"
-                "uadalp	v27.4s, v15.8h\n"
-                "addp	v17.4s, v18.4s, v19.4s\n"
-                "umull	v14.8h, v3.8b, %[b2a].8b\n"
                 "addp	v20.4s, v24.4s, v25.4s\n"
                 "addp	v21.4s, v26.4s, v27.4s\n"
-                "umull	v15.8h, v3.8b, %[b3a].8b\n"
-                "umlal2	v12.8h, v3.16b, %[b0a].16b\n"
-                "str	q17, [%[c_ptr], #16]\n"
-                "umlal2	v13.8h, v3.16b, %[b1a].16b\n"
-                "umlal2	v14.8h, v3.16b, %[b2a].16b\n"
-                "addp	v18.4s, v20.4s, v21.4s\n"
-                "umlal2	v15.8h, v3.16b, %[b3a].16b\n"
-                "b	3f\n"
-
-                // Detached final iteration (odd K)
-                "2:\n"
-                "umull	v14.8h, v0.8b, %[b2].8b\n"
-                "add	%[a_ptr], %[a_ptr], #64\n"
-                "umull	v15.8h, v0.8b, %[b3].8b\n"
-                "add	%[b_ptr], %[b_ptr], #64\n"
-                "umlal2	v12.8h, v0.16b, %[b0].16b\n"
-                "umlal2	v13.8h, v0.16b, %[b1].16b\n"
-                "umlal2	v14.8h, v0.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v0.16b, %[b3].16b\n"
+                "addp	v22.4s, v28.4s, v29.4s\n"
+                "addp	v23.4s, v30.4s, v31.4s\n"
 
-                "uadalp	v16.4s, v12.8h\n"
-                "umull	v12.8h, v1.8b, %[b0].8b\n"
-                "uadalp	v17.4s, v13.8h\n"
-                "uadalp	v18.4s, v14.8h\n"
-                "umull	v13.8h, v1.8b, %[b1].8b\n"
-                "uadalp	v19.4s, v15.8h\n"
-                "umull	v14.8h, v1.8b, %[b2].8b\n"
-                "umull	v15.8h, v1.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v1.16b, %[b0].16b\n"
                 "addp	v16.4s, v16.4s, v17.4s\n"
-                "umlal2	v13.8h, v1.16b, %[b1].16b\n"
                 "addp	v17.4s, v18.4s, v19.4s\n"
-                "umlal2	v14.8h, v1.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v1.16b, %[b3].16b\n"
-
-                "uadalp	v20.4s, v12.8h\n"
-                "umull	v12.8h, v2.8b, %[b0].8b\n"
-                "uadalp	v21.4s, v13.8h\n"
-                "uadalp	v22.4s, v14.8h\n"
-                "umull	v13.8h, v2.8b, %[b1].8b\n"
-                "uadalp	v23.4s, v15.8h\n"
-                "addp	v16.4s, v16.4s, v17.4s\n"
-                "umull	v14.8h, v2.8b, %[b2].8b\n"
                 "addp	v18.4s, v20.4s, v21.4s\n"
                 "addp	v19.4s, v22.4s, v23.4s\n"
-                "umull	v15.8h, v2.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v2.16b, %[b0].16b\n"
-                "str	q16, [%[c_ptr]]\n"
-                "umlal2	v13.8h, v2.16b, %[b1].16b\n"
-                "umlal2	v14.8h, v2.16b, %[b2].16b\n"
-                "umlal2	v15.8h, v2.16b, %[b3].16b\n"
 
-                "uadalp	v24.4s, v12.8h\n"
-                "umull	v12.8h, v3.8b, %[b0].8b\n"
-                "uadalp	v25.4s, v13.8h\n"
-                "uadalp	v26.4s, v14.8h\n"
-                "umull	v13.8h, v3.8b, %[b1].8b\n"
-                "uadalp	v27.4s, v15.8h\n"
-                "addp	v17.4s, v18.4s, v19.4s\n"
-                "umull	v14.8h, v3.8b, %[b2].8b\n"
-                "addp	v20.4s, v24.4s, v25.4s\n"
-                "addp	v21.4s, v26.4s, v27.4s\n"
-                "umull	v15.8h, v3.8b, %[b3].8b\n"
-                "umlal2	v12.8h, v3.16b, %[b0].16b\n"
+                "str	q16, [%[c_ptr]]\n"
                 "str	q17, [%[c_ptr], #16]\n"
-                "umlal2	v13.8h, v3.16b, %[b1].16b\n"
-                "umlal2	v14.8h, v3.16b, %[b2].16b\n"
-                "addp	v18.4s, v20.4s, v21.4s\n"
-                "umlal2	v15.8h, v3.16b, %[b3].16b\n"
-
-                "3:\n"
-
-                // Final additions
-                "uadalp	v28.4s, v12.8h\n"
                 "str	q18, [%[c_ptr], #32]\n"
-                "uadalp	v29.4s, v13.8h\n"
-                "uadalp	v30.4s, v14.8h\n"
-                "uadalp	v31.4s, v15.8h\n"
-
-                // Horizontal reduction, phase 1
-                "addp	v22.4s, v28.4s, v29.4s\n"
-                "addp	v23.4s, v30.4s, v31.4s\n"
-
-                // Horizontal reduction, phase 2
-                "addp	v19.4s, v22.4s, v23.4s\n"
                 "str	q19, [%[c_ptr], #48]\n"
                 "add	%[c_ptr], %[c_ptr], #64\n"
 
             :
               [a_ptr] "+r" (a_ptr), [b_ptr] "+r" (b_ptr), [c_ptr] "+r" (c_ptr),
               [b0] "+w" (b0), [b1] "+w" (b1), [b2] "+w" (b2), [b3] "+w" (b3),
-              [b0a] "+w" (b0a), [b1a] "+w" (b1a), [b2a] "+w" (b2a), [b3a] "+w" (b3a),
               [k] "+r" (k)
-            : [oddk] "r" (oddk)
+            :
             : "x20", "x21", "v0","v1","v2","v3","v12","v13","v14","v15","v16","v17","v18","v19",
               "v20","v21","v22","v23","v24","v25","v26","v27","v28","v29","v30","v31", "cc");
         }
diff --git a/tests/validation/fixtures/GEMMLowpAssemblyFixture.h b/tests/validation/fixtures/GEMMLowpAssemblyFixture.h
index ff33c9db39..d6b94a197d 100644
--- a/tests/validation/fixtures/GEMMLowpAssemblyFixture.h
+++ b/tests/validation/fixtures/GEMMLowpAssemblyFixture.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 ARM Limited.
+ * Copyright (c) 2017-2018 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -98,8 +98,8 @@ protected:
         }
         else
         {
-            fill(AccessorType(a), 0, 0, 128);
-            fill(AccessorType(b), 1, 0, 128);
+            fill(AccessorType(a), 0, 0, 255);
+            fill(AccessorType(b), 1, 0, 255);
         }
         fill(AccessorType(c), 2, 0, 0);
 
@@ -124,8 +124,8 @@ protected:
         }
         else
         {
-            fill(a, 0, 0, 128);
-            fill(b, 1, 0, 128);
+            fill(a, 0, 0, 255);
+            fill(b, 1, 0, 255);
         }
 
         return reference::gemmlowp<int32_t, T2>(a, b);