@@ -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);
When al == xzr, we cannot use addi/subi because that encodes xsp. Force a zero into the temp register for that (rare) case. Cc: qemu-stable@nongnu.org Signed-off-by: Richard Henderson <rth@twiddle.net> Message-Id: <20161207180727.6286-2-rth@twiddle.net> --- tcg/aarch64/tcg-target.inc.c | 9 +++++++++ 1 file changed, 9 insertions(+)