From 8403a5015c5d5ef01792dc5ebf3c10aa5594931f Mon Sep 17 00:00:00 2001 From: Peter Maydell Date: Tue, 5 Nov 2024 10:09:56 +0000 Subject: [PATCH] target/alpha: Explicitly set 2-NaN propagation rule MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Set the NaN propagation rule explicitly for the float_status word used in this target. This is a no-behaviour-change commit, so we retain the existing behaviour of x87-style pick-largest-significand NaN propagation. This is however not the architecturally correct handling, so we leave a TODO note to that effect. We also leave a TODO note pointing out that all this code in the cpu initfn (including the existing setting up of env->flags and the FPCR) should be in a currently non-existent CPU reset function. Signed-off-by: Peter Maydell Reviewed-by: Philippe Mathieu-Daudé Reviewed-by: Richard Henderson Message-id: 20241025141254.2141506-17-peter.maydell@linaro.org --- fpu/softfloat-specialize.c.inc | 2 +- target/alpha/cpu.c | 11 +++++++++++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/fpu/softfloat-specialize.c.inc b/fpu/softfloat-specialize.c.inc index 77ebc8216f..a5c3e2b8de 100644 --- a/fpu/softfloat-specialize.c.inc +++ b/fpu/softfloat-specialize.c.inc @@ -406,7 +406,7 @@ static int pickNaN(FloatClass a_cls, FloatClass b_cls, || defined(TARGET_LOONGARCH64) || defined(TARGET_HPPA) \ || defined(TARGET_S390X) || defined(TARGET_PPC) || defined(TARGET_M68K) \ || defined(TARGET_SPARC) || defined(TARGET_XTENSA) \ - || defined(TARGET_I386) + || defined(TARGET_I386) || defined(TARGET_ALPHA) g_assert_not_reached(); #else rule = float_2nan_prop_x87; diff --git a/target/alpha/cpu.c b/target/alpha/cpu.c index 9db1dffc03..5d75c941f7 100644 --- a/target/alpha/cpu.c +++ b/target/alpha/cpu.c @@ -24,6 +24,7 @@ #include "qemu/qemu-print.h" #include "cpu.h" #include "exec/exec-all.h" +#include "fpu/softfloat.h" static void alpha_cpu_set_pc(CPUState *cs, vaddr value) @@ -187,7 +188,17 @@ static void alpha_cpu_initfn(Object *obj) { CPUAlphaState *env = cpu_env(CPU(obj)); + /* TODO all this should be done in reset, not init */ + env->lock_addr = -1; + + /* + * TODO: this is incorrect. The Alpha Architecture Handbook version 4 + * describes NaN propagation in section 4.7.10.4. We should prefer + * the operand in Fb (whether it is a QNaN or an SNaN), then the + * operand in Fa. That is float_2nan_prop_ba. + */ + set_float_2nan_prop_rule(float_2nan_prop_x87, &env->fp_status); #if defined(CONFIG_USER_ONLY) env->flags = ENV_FLAG_PS_USER | ENV_FLAG_FEN; cpu_alpha_store_fpcr(env, (uint64_t)(FPCR_INVD | FPCR_DZED | FPCR_OVFD