Add AMO + timer testcase

test/sim/amo_timer_irq/Makefile

@@ -0,0 +1,5 @@
+SRCS := ../common/init.S main.c
+APP  := amo_timer_irq
+CCFLAGS = -march=rv32imac -Os
+
+include ../common/src_only_app.mk

test/sim/amo_timer_irq/amo_timer_irq.gtkw

@@ -0,0 +1,46 @@
+[*]
+[*] GTKWave Analyzer v3.3.103 (w)1999-2019 BSI
+[*] Sat Dec  4 23:25:19 2021
+[*]
+[dumpfile] "amo_timer_irq_run.vcd"
+[dumpfile_mtime] "Sat Dec  4 23:21:36 2021"
+[dumpfile_size] 6246687
+[savefile] "/home/luke/proj/hazard3/test/sim/amo_smoke/amo_smoke.gtkw"
+[timestart] 420
+[size] 1975 1095
+[pos] -1 -1
+*-3.000000 458 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1 -1
+[treeopen] core.
+[sst_width] 233
+[signals_width] 246
+[sst_expanded] 1
+[sst_vpaned_height] 317
+@22
+core.d_pc[31:0]
+@28
+core.mw_local_exclusive_reserved
+core.m_stall
+core.x_stall
+core.x_stall_on_amo
+@200
+-
+@22
+d_haddr[31:0]
+@28
+d_htrans[1:0]
+d_hsize[2:0]
+@29
+d_hexcl
+@28
+d_hwrite
+d_hready
+@22
+d_hwdata[31:0]
+d_hrdata[31:0]
+@200
+-
+@22
+core.x_rs2_bypass[31:0]
+core.xm_store_data[31:0]
+[pattern_trace] 1
+[pattern_trace] 0

test/sim/amo_timer_irq/main.c

@@ -0,0 +1,45 @@
+#include "tb_cxxrtl_io.h"
+#include <stdint.h>
+
+// Serve timer IRQs in the background whilst performing AMOs in a loop in the
+// foreground.
+
+#define IRQ_INTERVAL 201
+#define N_AMOS 1000
+
+#define test_assert(cond, ...) if (!(cond)) {tb_printf(__VA_ARGS__); return -1;}
+
+volatile uint32_t amo_count, irq_count;
+
+void __attribute__((interrupt)) isr_machine_timer() {
+	mm_timer->mtimecmp = mm_timer->mtimecmp + IRQ_INTERVAL;
+	++irq_count;
+}
+
+int main() {
+	amo_count = 0;
+	irq_count = 0;
+
+	asm volatile ("csrw mie, %0" : : "r" (0x80));
+	mm_timer->mtime = 0;
+	// Will take first timer interrupt immediately:
+	asm volatile ("csrsi mstatus, 0x8");
+
+	for (uint32_t i = 0; i < N_AMOS; i = i + 1) {
+		uint32_t fetch;
+		asm volatile (
+			"amoadd.w %0, %1, (%2)"
+			: "=r" (fetch)
+			: "r" (1), "r" (&amo_count)
+		);
+		test_assert(fetch == i, "Bad fetch, expected %u, got %u\n", i, fetch);
+	}
+
+	asm volatile ("csrci mstatus, 0x8");
+	uint32_t current_time = mm_timer->mtime;
+	tb_printf("At time %u, received %u IRQs\n", current_time, irq_count);
+	test_assert(current_time / IRQ_INTERVAL + 1 == irq_count, "Bad IRQ count\n");
+	test_assert(amo_count == N_AMOS, "Bad final AMO count %u\n", N_AMOS);
+
+	return 0;
+}