From 2911e9b95f3bb03783ae5ca3e2494dc3b44a9161 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Tue, 26 Mar 2024 11:21:38 -1000 Subject: [PATCH] tcg/optimize: Fix sign_mask for logical right-shift MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The 'sign' computation is attempting to locate the sign bit that has been repeated, so that we can test if that bit is known zero. That computation can be zero if there are no known sign repetitions. Cc: qemu-stable@nongnu.org Fixes: 93a967fbb57 ("tcg/optimize: Propagate sign info for shifting") Resolves: https://gitlab.com/qemu-project/qemu/-/issues/2248 Signed-off-by: Richard Henderson Reviewed-by: Philippe Mathieu-Daudé --- tcg/optimize.c | 2 +- tests/tcg/aarch64/Makefile.target | 1 + tests/tcg/aarch64/test-2248.c | 28 ++++++++++++++++++++++++++++ 3 files changed, 30 insertions(+), 1 deletion(-) create mode 100644 tests/tcg/aarch64/test-2248.c diff --git a/tcg/optimize.c b/tcg/optimize.c index 752cc5c56b..275db77b42 100644 --- a/tcg/optimize.c +++ b/tcg/optimize.c @@ -2376,7 +2376,7 @@ static bool fold_shift(OptContext *ctx, TCGOp *op) * will not reduced the number of input sign repetitions. */ sign = (s_mask & -s_mask) >> 1; - if (!(z_mask & sign)) { + if (sign && !(z_mask & sign)) { ctx->s_mask = s_mask; } break; diff --git a/tests/tcg/aarch64/Makefile.target b/tests/tcg/aarch64/Makefile.target index ea3e232e65..0efd565f05 100644 --- a/tests/tcg/aarch64/Makefile.target +++ b/tests/tcg/aarch64/Makefile.target @@ -10,6 +10,7 @@ VPATH += $(AARCH64_SRC) # Base architecture tests AARCH64_TESTS=fcvt pcalign-a64 lse2-fault +AARCH64_TESTS += test-2248 fcvt: LDFLAGS+=-lm diff --git a/tests/tcg/aarch64/test-2248.c b/tests/tcg/aarch64/test-2248.c new file mode 100644 index 0000000000..aac2e17836 --- /dev/null +++ b/tests/tcg/aarch64/test-2248.c @@ -0,0 +1,28 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* See https://gitlab.com/qemu-project/qemu/-/issues/2248 */ + +#include + +__attribute__((noinline)) +long test(long x, long y, long sh) +{ + long r; + asm("cmp %1, %2\n\t" + "cset x12, lt\n\t" + "and w11, w12, #0xff\n\t" + "cmp w11, #0\n\t" + "csetm x14, ne\n\t" + "lsr x13, x14, %3\n\t" + "sxtb %0, w13" + : "=r"(r) + : "r"(x), "r"(y), "r"(sh) + : "x11", "x12", "x13", "x14"); + return r; +} + +int main() +{ + long r = test(0, 1, 2); + assert(r == -1); + return 0; +}