From 80a9d720ca0ae21e124a69ee4608306af5aa151c Mon Sep 17 00:00:00 2001
From: Gino Lu <gino.lu@amd.com>
Date: Wed, 30 Jul 2025 22:29:04 +0800
Subject: [PATCH] add constexpr to pk_fp4::pack/unpack() (#2586)

[ROCm/composable_kernel commit: b25d512e8abbd2eb6a12171d12739a144307d809]
---
 include/ck_tile/core/numeric/pk_fp4.hpp | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/include/ck_tile/core/numeric/pk_fp4.hpp b/include/ck_tile/core/numeric/pk_fp4.hpp
index b7dca9dd0a..0dee750b69 100644
--- a/include/ck_tile/core/numeric/pk_fp4.hpp
+++ b/include/ck_tile/core/numeric/pk_fp4.hpp
@@ -55,8 +55,8 @@ struct pk_float4_e2m1_t
     CK_TILE_HOST_DEVICE constexpr operator bf16x2_t() const;
 
     template <index_t I>
-    CK_TILE_HOST_DEVICE raw_type unpack(number<I>) const;
-    CK_TILE_HOST_DEVICE static pk_float4_e2m1_t pack(const type x0, const type x1)
+    CK_TILE_HOST_DEVICE constexpr raw_type unpack(number<I>) const;
+    CK_TILE_HOST_DEVICE constexpr static pk_float4_e2m1_t pack(const type x0, const type x1)
     {
         return (x1 << 4) | (x0 & 0b00001111);
     }
@@ -130,7 +130,7 @@ struct numeric<pk_fp4_t>
 };
 
 template <index_t I>
-CK_TILE_HOST_DEVICE pk_fp4_raw_t pk_fp4_t::unpack(number<I>) const
+CK_TILE_HOST_DEVICE constexpr pk_fp4_raw_t pk_fp4_t::unpack(number<I>) const
 {
     static_assert(I < 2, "Index is out of range.");
     if constexpr(I == 1)
@@ -147,7 +147,6 @@ namespace impl {
 template <typename T>
 CK_TILE_DEVICE T _from_f4(pk_fp4_raw_t src, float scale = 1.0f)
 {
-    // TODO: check the order
     if constexpr(std::is_same_v<T, fp32_t>)
         return fp32x2_t(__builtin_amdgcn_cvt_scalef32_pk_f32_fp4(src, scale, 0))[0];
     else if constexpr(std::is_same_v<T, fp32x2_t>)
@@ -167,7 +166,6 @@ CK_TILE_DEVICE T _from_f4(pk_fp4_raw_t src, float scale = 1.0f)
 template <typename T>
 CK_TILE_DEVICE pk_fp4_raw_t _to_f4(T src, float scale = 1.0f)
 {
-    // TODO: check the order
     union
     {
         uint32_t u32;