From: Peter Maydell <peter.maydell@linaro.org>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [PULL 11/24] target-arm: Eliminate unnecessary zero-extend in disas_bitfield
Date: Mon, 14 Sep 2015 14:52:58 +0100 [thread overview]
Message-ID: <1442238791-30255-12-git-send-email-peter.maydell@linaro.org> (raw)
In-Reply-To: <1442238791-30255-1-git-send-email-peter.maydell@linaro.org>
From: Richard Henderson <rth@twiddle.net>
For !SF, this initial ext32u can't be optimized away by the
current TCG code generator. (It would require backward bit
liveness propagation.)
But since the range of bits for !SF are already constrained by
unallocated_encoding, we'll never reference the high bits anyway.
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <rth@twiddle.net>
Message-id: 1441909103-24666-10-git-send-email-rth@twiddle.net
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
target-arm/translate-a64.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/target-arm/translate-a64.c b/target-arm/translate-a64.c
index f2f8443..3ab0b42 100644
--- a/target-arm/translate-a64.c
+++ b/target-arm/translate-a64.c
@@ -3015,7 +3015,11 @@ static void disas_bitfield(DisasContext *s, uint32_t insn)
}
tcg_rd = cpu_reg(s, rd);
- tcg_tmp = read_cpu_reg(s, rn, sf);
+
+ /* Suppress the zero-extend for !sf. Since RI and SI are constrained
+ to be smaller than bitsize, we'll never reference data outside the
+ low 32-bits anyway. */
+ tcg_tmp = read_cpu_reg(s, rn, 1);
/* Recognize the common aliases. */
if (opc == 0) { /* SBFM */
--
1.9.1
next prev parent reply other threads:[~2015-09-14 13:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-14 13:52 [Qemu-devel] [PULL 00/24] target-arm queue Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 01/24] arm: xlnx-zynqmp: Fix up GIC region size Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 02/24] xlnx-zynqmp: Remove unnecessary brackets around error messages Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 03/24] target-arm: Share all common TCG temporaries Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 04/24] target-arm: Introduce DisasCompare Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 05/24] target-arm: Handle always condition codes within arm_test_cc Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 06/24] target-arm: Use setcond and movcond for csel Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 07/24] target-arm: Implement ccmp branchless Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 08/24] target-arm: Implement fcsel with movcond Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 09/24] target-arm: Recognize SXTB, SXTH, SXTW, ASR Peter Maydell
2015-09-14 13:52 ` [Qemu-devel] [PULL 10/24] target-arm: Recognize UXTB, UXTH, LSR, LSL Peter Maydell
2015-09-14 13:52 ` Peter Maydell [this message]
2015-09-14 13:52 ` [Qemu-devel] [PULL 12/24] target-arm: Recognize ROR Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 13/24] target-arm: Use tcg_gen_extrh_i64_i32 Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 14/24] i.MX: Add GPIO device Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 15/24] i.MX: Add GPIO devices to i.MX31 SOC Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 16/24] i.MX: Add GPIO devices to i.MX25 SOC Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 17/24] hw/cpu/{a15mpcore, a9mpcore}: Handle missing has_el3 CPU props gracefully Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 18/24] target-arm: Add VTCR_EL2 Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 19/24] target-arm: Add VTTBR_EL2 Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 20/24] target-arm: Suppress TBI for S2 translations Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 21/24] target-arm: Suppress EPD for S2, EL2 and EL3 translations Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 22/24] target-arm: Add VPIDR_EL2 Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 23/24] target-arm: Break out mpidr_read_val() Peter Maydell
2015-09-14 13:53 ` [Qemu-devel] [PULL 24/24] target-arm: Add VMPIDR_EL2 Peter Maydell
2015-09-14 15:12 ` [Qemu-devel] [PULL 00/24] target-arm queue Peter Maydell
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