Validate gfx1201 WMMA layout and compile first K kernel

tools/windows/wmma_gfx1201.hip

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+// Independent gfx12 WMMA layout probe. This deliberately does not use d4r fragments.
+// A and B are row-major [logical row/column][K]; the intrinsic receives B,A
+// so its output is row=A, column=B, as in AMD's RDNA 4 WMMA guide.
+using h8 = _Float16 __attribute__((ext_vector_type(8)));
+using f8 = float __attribute__((ext_vector_type(8)));
+#include "../../kernels/common/wmma_backend.h"
+
+extern "C" __attribute__((global)) void d4r_wmma_swap_test(float* output)
+{
+    const unsigned int lane = __builtin_amdgcn_workitem_id_x();
+    if (lane < 32u) {
+        output[lane] = d4r_wmma_other_half(static_cast<float>(lane));
+        output[32u + lane] = static_cast<float>(__builtin_amdgcn_mbcnt_lo(~0u, 0u));
+    }
+}
+
+extern "C" __attribute__((global)) void d4r_wmma_gfx1201(
+    const unsigned short* a_bits, const unsigned short* b_bits,
+    const float* initial_c, float* output, unsigned int steps)
+{
+    const unsigned int lane = __builtin_amdgcn_workitem_id_x();
+    if (lane >= 32u) return;
+    const unsigned int row = lane & 15u;
+    const unsigned int group = lane >> 4;
+    const _Float16* a = reinterpret_cast<const _Float16*>(a_bits);
+    const _Float16* b = reinterpret_cast<const _Float16*>(b_bits);
+    h8 a_frag, b_frag;
+    f8 c_frag;
+    for (unsigned int i = 0; i < 8u; ++i) {
+        a_frag[i] = a[row * 16u + group * 8u + i];
+        b_frag[i] = b[row * 16u + group * 8u + i];
+        c_frag[i] = initial_c[row * 16u + group * 8u + i];
+    }
+    f8 result = __builtin_amdgcn_wmma_f32_16x16x16_f16_w32_gfx12(
+        b_frag, a_frag, c_frag);
+    if (steps == 2u)
+        result = __builtin_amdgcn_wmma_f32_16x16x16_f16_w32_gfx12(
+            b_frag, a_frag, result);
+    for (unsigned int i = 0; i < 8u; ++i)
+        output[row * 16u + group * 8u + i] = result[i];
+}
+
+// d4r's original gfx11 fragment contract, exercised independently of K/M.
+extern "C" __attribute__((global)) void d4r_wmma_legacy_contract(
+    const unsigned short* a_bits, const unsigned short* b_bits,
+    const float* initial_c, float* output, unsigned int steps)
+{
+    const unsigned int lane = __builtin_amdgcn_workitem_id_x();
+    if (lane >= 32u) return;
+    const unsigned int token = lane & 15u;
+    const unsigned int group = lane >> 4;
+    const _Float16* a = reinterpret_cast<const _Float16*>(a_bits);
+    const _Float16* b = reinterpret_cast<const _Float16*>(b_bits);
+    d4r_wmma_h16 a_frag, b_frag;
+    d4r_wmma_f8 c_frag;
+    for (unsigned int i = 0; i < 16u; ++i) {
+        a_frag[i] = a[token * 16u + i];
+        b_frag[i] = b[token * 16u + i];
+    }
+    for (unsigned int i = 0; i < 8u; ++i)
+        c_frag[i] = initial_c[(2u * i + group) * 16u + token];
+    d4r_wmma_f8 result = d4r_wmma_legacy_layout(a_frag, b_frag, c_frag);
+    if (steps == 2u)
+        result = d4r_wmma_legacy_layout(a_frag, b_frag, result);
+    for (unsigned int i = 0; i < 8u; ++i)
+        output[(2u * i + group) * 16u + token] = result[i];
+}