From d0414d71f612651699de019b911a772b07d0ac4a Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 22 May 2024 14:39:14 +0200 Subject: [PATCH] target/i386: generate simpler code for ROL/ROR with immediate count gen_rot_carry and gen_rot_overflow are meant to be called with count == NULL if the count cannot be zero. However this is not done in gen_ROL and gen_ROR, and writing everywhere "can_be_zero ? count : NULL" is burdensome and less readable. Just pass can_be_zero as a separate argument. gen_RCL and gen_RCR use a conditional branch to skip the computation if count is zero, so they can pass false unconditionally to gen_rot_overflow. Signed-off-by: Paolo Bonzini Reviewed-by: Richard Henderson Message-ID: <20240522123914.608516-1-pbonzini@redhat.com> Signed-off-by: Paolo Bonzini --- target/i386/tcg/emit.c.inc | 26 ++++++++++++++------------ 1 file changed, 14 insertions(+), 12 deletions(-) diff --git a/target/i386/tcg/emit.c.inc b/target/i386/tcg/emit.c.inc index 2dee33dd48..33cb59e54b 100644 --- a/target/i386/tcg/emit.c.inc +++ b/target/i386/tcg/emit.c.inc @@ -2901,14 +2901,15 @@ static bool gen_eflags_adcox(DisasContext *s, X86DecodedInsn *decode, bool want_ return got_cf; } -static void gen_rot_overflow(X86DecodedInsn *decode, TCGv result, TCGv old, TCGv count) +static void gen_rot_overflow(X86DecodedInsn *decode, TCGv result, TCGv old, + bool can_be_zero, TCGv count) { MemOp ot = decode->op[0].ot; - TCGv temp = count ? tcg_temp_new() : decode->cc_src2; + TCGv temp = can_be_zero ? tcg_temp_new() : decode->cc_src2; tcg_gen_xor_tl(temp, old, result); tcg_gen_extract_tl(temp, temp, (8 << ot) - 1, 1); - if (count) { + if (can_be_zero) { tcg_gen_movcond_tl(TCG_COND_EQ, decode->cc_src2, count, tcg_constant_tl(0), decode->cc_src2, temp); } @@ -3000,7 +3001,7 @@ static void gen_RCL(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode) /* Compute result and outgoing overflow */ tcg_gen_mov_tl(decode->cc_src2, s->T0); tcg_gen_or_tl(s->T0, low, high); - gen_rot_overflow(decode, s->T0, decode->cc_src2, NULL); + gen_rot_overflow(decode, s->T0, decode->cc_src2, false, NULL); if (zero_label) { gen_set_label(zero_label); @@ -3053,7 +3054,7 @@ static void gen_RCR(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode) /* Compute result and outgoing overflow */ tcg_gen_mov_tl(decode->cc_src2, s->T0); tcg_gen_or_tl(s->T0, low, high); - gen_rot_overflow(decode, s->T0, decode->cc_src2, NULL); + gen_rot_overflow(decode, s->T0, decode->cc_src2, false, NULL); if (zero_label) { gen_set_label(zero_label); @@ -3129,9 +3130,10 @@ static TCGv_i32 gen_rot_replicate(MemOp ot, TCGv in) } } -static void gen_rot_carry(X86DecodedInsn *decode, TCGv result, TCGv count, int bit) +static void gen_rot_carry(X86DecodedInsn *decode, TCGv result, + bool can_be_zero, TCGv count, int bit) { - if (count == NULL) { + if (!can_be_zero) { tcg_gen_extract_tl(decode->cc_dst, result, bit, 1); } else { TCGv temp = tcg_temp_new(); @@ -3165,8 +3167,8 @@ static void gen_ROL(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode) } else { tcg_gen_rotl_tl(s->T0, s->T0, count); } - gen_rot_carry(decode, s->T0, count, 0); - gen_rot_overflow(decode, s->T0, old, count); + gen_rot_carry(decode, s->T0, can_be_zero, count, 0); + gen_rot_overflow(decode, s->T0, old, can_be_zero, count); } static void gen_ROR(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode) @@ -3190,12 +3192,12 @@ static void gen_ROR(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode) tcg_gen_rotr_i32(temp32, temp32, count32); /* Zero extend to facilitate later optimization. */ tcg_gen_extu_i32_tl(s->T0, temp32); - gen_rot_carry(decode, s->T0, count, 31); + gen_rot_carry(decode, s->T0, can_be_zero, count, 31); } else { tcg_gen_rotr_tl(s->T0, s->T0, count); - gen_rot_carry(decode, s->T0, count, TARGET_LONG_BITS - 1); + gen_rot_carry(decode, s->T0, can_be_zero, count, TARGET_LONG_BITS - 1); } - gen_rot_overflow(decode, s->T0, old, count); + gen_rot_overflow(decode, s->T0, old, can_be_zero, count); } static void gen_RORX(DisasContext *s, CPUX86State *env, X86DecodedInsn *decode)