From dcda42e7dcdb5e260013757763bf5dbf67d69568 Mon Sep 17 00:00:00 2001 From: "James Helferty (NVIDIA)" Date: Fri, 15 Aug 2025 09:21:48 -0700 Subject: Use 64bit int instead of emulation on metal (#8180) Metal's popcount prototype is `T popcount(T x)` but we want to use it to implement `countbits` where the prototype always returns `uint`. Using `popcount` directly would implicitly cast successfully to the 32-bit return value in all cases except when the argument is a 64-bit type. Thus, this change always explicitly casts the result to `$TR`, which should be one of the `uint[N]` types, and should always be able to hold the number of bits in the type. Addresses #6877 --- source/slang/hlsl.meta.slang | 24 ++---------------------- 1 file changed, 2 insertions(+), 22 deletions(-) (limited to 'source/slang') diff --git a/source/slang/hlsl.meta.slang b/source/slang/hlsl.meta.slang index 78f6a4eb8..0d5b8cb1f 100644 --- a/source/slang/hlsl.meta.slang +++ b/source/slang/hlsl.meta.slang @@ -8190,19 +8190,7 @@ uint countbits(T value) __intrinsic_asm "bitCount"; } case metal: - if (T is int64_t || T is uint64_t) - { - return __emulatedCountbits64(__intCast(value)); - } - else if (T is int16_t || T is uint16_t) - { - // emulate 16-bit - return countbits(__intCast(value)); - } - else - { - __intrinsic_asm "popcount"; - } + __intrinsic_asm "($TR)popcount($0)"; case cuda: case cpp: __intrinsic_asm "$P_countbits($0)"; @@ -8262,15 +8250,7 @@ vector countbits(vector value) __intrinsic_asm "bitCount"; } case metal: - if(T is int64_t || T is uint64_t || T is int16_t || T is uint16_t) - { - // Emulate 64-bit and 16-bit - VECTOR_MAP_UNARY(uint, N, countbits, value); - } - else - { - __intrinsic_asm "popcount"; - } + __intrinsic_asm "($TR)popcount($0)"; case spirv: if(T is int64_t || T is uint64_t || T is int16_t || T is uint16_t) { -- cgit v1.2.3