From a56e0c65b08f0f7123630f3a1b415e67ef48c38e Mon Sep 17 00:00:00 2001 From: Xavier Leroy Date: Sat, 25 Jul 2020 18:27:04 +0200 Subject: AArch64 implementation of __builtin_ctz* Using the "rbit" instruction (reverse bits). --- aarch64/Asmexpand.ml | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'aarch64/Asmexpand.ml') diff --git a/aarch64/Asmexpand.ml b/aarch64/Asmexpand.ml index dcb2d1aa..02c27053 100644 --- a/aarch64/Asmexpand.ml +++ b/aarch64/Asmexpand.ml @@ -337,7 +337,7 @@ let expand_builtin_inline name args res = | "__builtin_bswap16", [BA(IR a1)], BR(IR res) -> emit (Prev16(W, res, a1)); emit (Pandimm(W, res, RR0 res, Z.of_uint 0xFFFF)) - (* Count leading zeros and leading sign bits *) + (* Count leading zeros, leading sign bits, trailing zeros *) | "__builtin_clz", [BA(IR a1)], BR(IR res) -> emit (Pclz(W, res, a1)) | ("__builtin_clzl" | "__builtin_clzll"), [BA(IR a1)], BR(IR res) -> @@ -346,6 +346,12 @@ let expand_builtin_inline name args res = emit (Pcls(W, res, a1)) | ("__builtin_clsl" | "__builtin_clsll"), [BA(IR a1)], BR(IR res) -> emit (Pcls(X, res, a1)) + | "__builtin_ctz", [BA(IR a1)], BR(IR res) -> + emit (Prbit(W, res, a1)); + emit (Pclz(W, res, res)) + | ("__builtin_ctzl" | "__builtin_ctzll"), [BA(IR a1)], BR(IR res) -> + emit (Prbit(X, res, a1)); + emit (Pclz(X, res, res)) (* Float arithmetic *) | "__builtin_fsqrt", [BA(FR a1)], BR(FR res) -> emit (Pfsqrt(D, res, a1)) -- cgit