From b1eb20da625897244e9621dabcf63d899deca54d Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Wed, 7 Dec 2016 10:07:26 -0800 Subject: tcg/aarch64: Fix addsub2 for 0+C When al == xzr, we cannot use addi/subi because that encodes xsp. Force a zero into the temp register for that (rare) case. Signed-off-by: Richard Henderson Message-Id: <20161207180727.6286-2-rth@twiddle.net> --- tcg/aarch64/tcg-target.inc.c | 9 +++++++++ 1 file changed, 9 insertions(+) (limited to 'tcg') diff --git a/tcg/aarch64/tcg-target.inc.c b/tcg/aarch64/tcg-target.inc.c index 585b0d6234..deb59674af 100644 --- a/tcg/aarch64/tcg-target.inc.c +++ b/tcg/aarch64/tcg-target.inc.c @@ -964,6 +964,15 @@ static inline void tcg_out_addsub2(TCGContext *s, int ext, TCGReg rl, insn = I3401_SUBSI; bl = -bl; } + if (unlikely(al == TCG_REG_XZR)) { + /* ??? We want to allow al to be zero for the benefit of + negation via subtraction. However, that leaves open the + possibility of adding 0+const in the low part, and the + immediate add instructions encode XSP not XZR. Don't try + anything more elaborate here than loading another zero. */ + al = TCG_REG_TMP; + tcg_out_movi(s, ext, al, 0); + } tcg_out_insn_3401(s, insn, ext, rl, al, bl); } else { tcg_out_insn_3502(s, sub ? I3502_SUBS : I3502_ADDS, ext, rl, al, bl); -- cgit v1.2.1