py/nlrrv32: Add RISC-V RV32I NLR implementation.

Add custom NLR support for 32 bits RISC-V RV32I targets.

Signed-off-by: Alessandro Gatti <a.gatti@frob.it>

py/nlr.h

@@ -44,6 +44,7 @@
 #define MICROPY_NLR_NUM_REGS_MIPS           (13)
 #define MICROPY_NLR_NUM_REGS_XTENSA         (10)
 #define MICROPY_NLR_NUM_REGS_XTENSAWIN      (17)
+#define MICROPY_NLR_NUM_REGS_RV32I          (14)
 
 // *FORMAT-OFF*
 
@@ -88,6 +89,9 @@
 #elif defined(__mips__)
     #define MICROPY_NLR_MIPS (1)
     #define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_MIPS)
+#elif defined(__riscv) && defined(__riscv_xlen) && (__riscv_xlen == 32)
+    #define MICROPY_NLR_RV32I (1)
+    #define MICROPY_NLR_NUM_REGS (MICROPY_NLR_NUM_REGS_RV32I)
 #else
     #define MICROPY_NLR_SETJMP (1)
     //#warning "No native NLR support for this arch, using setjmp implementation"

py/nlrrv32.c

@@ -0,0 +1,81 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2024 Alessandro Gatti
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/mpstate.h"
+
+#if MICROPY_NLR_RV32I
+
+#undef nlr_push
+
+__attribute__((naked)) unsigned int nlr_push(nlr_buf_t *nlr) {
+    __asm volatile (
+        "sw   x1,  8(x10)       \n" // Store RA.
+        "sw   x8, 12(x10)       \n" // Store S0.
+        "sw   x9, 16(x10)       \n" // Store S1.
+        "sw  x18, 20(x10)       \n" // Store S2.
+        "sw  x19, 24(x10)       \n" // Store S3.
+        "sw  x20, 28(x10)       \n" // Store S4.
+        "sw  x21, 32(x10)       \n" // Store S5.
+        "sw  x22, 36(x10)       \n" // Store S6.
+        "sw  x23, 40(x10)       \n" // Store S7.
+        "sw  x24, 44(x10)       \n" // Store S8.
+        "sw  x25, 48(x10)       \n" // Store S9.
+        "sw  x26, 52(x10)       \n" // Store S10.
+        "sw  x27, 56(x10)       \n" // Store S11.
+        "sw   x2, 60(x10)       \n" // Store SP.
+        "jal  x0, nlr_push_tail \n" // Jump to the C part.
+        );
+}
+
+NORETURN void nlr_jump(void *val) {
+    MP_NLR_JUMP_HEAD(val, top)
+    __asm volatile (
+        "add  x10, x0, %0  \n" // Load nlr_buf address.
+        "lw   x1,  8(x10)  \n" // Retrieve RA.
+        "lw   x8, 12(x10)  \n" // Retrieve S0.
+        "lw   x9, 16(x10)  \n" // Retrieve S1.
+        "lw  x18, 20(x10)  \n" // Retrieve S2.
+        "lw  x19, 24(x10)  \n" // Retrieve S3.
+        "lw  x20, 28(x10)  \n" // Retrieve S4.
+        "lw  x21, 32(x10)  \n" // Retrieve S5.
+        "lw  x22, 36(x10)  \n" // Retrieve S6.
+        "lw  x23, 40(x10)  \n" // Retrieve S7.
+        "lw  x24, 44(x10)  \n" // Retrieve S8.
+        "lw  x25, 48(x10)  \n" // Retrieve S9.
+        "lw  x26, 52(x10)  \n" // Retrieve S10.
+        "lw  x27, 56(x10)  \n" // Retrieve S11.
+        "lw   x2, 60(x10)  \n" // Retrieve SP.
+        "addi x10, x0, 1   \n" // Return 1 for a non-local return.
+        "jalr  x0, x1, 0   \n" // Return.
+        :                      // Outputs.
+        : "r" (top)            // Inputs.
+        : "memory"             // Clobbered.
+        );
+
+    MP_UNREACHABLE
+}
+
+#endif // MICROPY_NLR_RV32I

py/py.cmake

@@ -55,6 +55,7 @@ set(MICROPY_SOURCE_PY
     ${MICROPY_PY_DIR}/nlr.c
     ${MICROPY_PY_DIR}/nlrmips.c
     ${MICROPY_PY_DIR}/nlrpowerpc.c
+    ${MICROPY_PY_DIR}/nlrrv32.c
     ${MICROPY_PY_DIR}/nlrsetjmp.c
     ${MICROPY_PY_DIR}/nlrthumb.c
     ${MICROPY_PY_DIR}/nlrx64.c

py/py.mk

@@ -83,6 +83,7 @@ PY_CORE_O_BASENAME = $(addprefix py/,\
 	nlrmips.o \
 	nlrpowerpc.o \
 	nlrxtensa.o \
+	nlrrv32.o \
 	nlrsetjmp.o \
 	malloc.o \
 	gc.o \