From: Richard Henderson <richard.henderson@linaro.org>
We were matching a signed 13-bit range, not a 12-bit range.
Expand the commentary within the function and be explicit
about all of the ranges.
Reported-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: LIU Zhiwei <zhiwei_liu@linux.alibaba.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Message-Id: <20221022095821.2441874-1-richard.henderson@linaro.org>
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
---
tcg/riscv/tcg-target.c.inc | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/tcg/riscv/tcg-target.c.inc b/tcg/riscv/tcg-target.c.inc
index 81a83e45b1..191197853f 100644
--- a/tcg/riscv/tcg-target.c.inc
+++ b/tcg/riscv/tcg-target.c.inc
@@ -154,13 +154,26 @@ static bool tcg_target_const_match(int64_t val, TCGType type, int ct)
if ((ct & TCG_CT_CONST_ZERO) && val == 0) {
return 1;
}
- if ((ct & TCG_CT_CONST_S12) && val == sextreg(val, 0, 12)) {
+ /*
+ * Sign extended from 12 bits: [-0x800, 0x7ff].
+ * Used for most arithmetic, as this is the isa field.
+ */
+ if ((ct & TCG_CT_CONST_S12) && val >= -0x800 && val <= 0x7ff) {
return 1;
}
- if ((ct & TCG_CT_CONST_N12) && -val == sextreg(-val, 0, 12)) {
+ /*
+ * Sign extended from 12 bits, negated: [-0x7ff, 0x800].
+ * Used for subtraction, where a constant must be handled by ADDI.
+ */
+ if ((ct & TCG_CT_CONST_N12) && val >= -0x7ff && val <= 0x800) {
return 1;
}
- if ((ct & TCG_CT_CONST_M12) && val >= -0xfff && val <= 0xfff) {
+ /*
+ * Sign extended from 12 bits, +/- matching: [-0x7ff, 0x7ff].
+ * Used by addsub2, which may need the negative operation,
+ * and requires the modified constant to be representable.
+ */
+ if ((ct & TCG_CT_CONST_M12) && val >= -0x7ff && val <= 0x7ff) {
return 1;
}
return 0;
--
2.39.0