shared/runtime/gchelper: Add LoongArch64 GC helper.

agatti · dpgeorge · commit e2e71a4237d3 · 2026-06-12T17:05:07.000+10:00
This commit provides optimised function implementations for the GC
helper function to collect register values.

Both a generic C version and a pure assembler version are provided by
these changes, collecting the subset of callee-save registers mentioned
in the LoongArch64 ABI document (S0-S9).

As for the other platforms, it is preferable to use the assembler
version whenever possible, although both were found to be working.

Signed-off-by: Alessandro Gatti &lt;a.gatti@frob.it&gt;
diff --git a/shared/runtime/gchelper.h b/shared/runtime/gchelper.h
@@ -43,6 +43,8 @@ typedef uintptr_t gc_helper_regs_t[10];
 typedef uintptr_t gc_helper_regs_t[11]; // x19-x29
 #elif defined(__riscv) && (__riscv_xlen <= 64)
 typedef uintptr_t gc_helper_regs_t[12]; // S0-S11
+#elif defined(__loongarch__) && defined(__loongarch64)
+typedef uintptr_t gc_helper_regs_t[10]; // S0-S9
 #endif
 
 #endif
diff --git a/shared/runtime/gchelper_generic.c b/shared/runtime/gchelper_generic.c
@@ -189,6 +189,32 @@ static void gc_helper_get_regs(gc_helper_regs_t arr) {
     arr[11] = s11;
 }
 
+#elif defined(__loongarch__) && defined(__loongarch64)
+
+// Fallback implementation for LOONG64, prefer gchelper_loong64.s.
+static void gc_helper_get_regs(gc_helper_regs_t arr) {
+    register uintptr_t s0 asm ("r23");
+    register uintptr_t s1 asm ("r24");
+    register uintptr_t s2 asm ("r25");
+    register uintptr_t s3 asm ("r26");
+    register uintptr_t s4 asm ("r27");
+    register uintptr_t s5 asm ("r28");
+    register uintptr_t s6 asm ("r29");
+    register uintptr_t s7 asm ("r30");
+    register uintptr_t s8 asm ("r31");
+    register uintptr_t s9 asm ("r22");
+    arr[0] = s0;
+    arr[1] = s1;
+    arr[2] = s2;
+    arr[3] = s3;
+    arr[4] = s4;
+    arr[5] = s5;
+    arr[6] = s6;
+    arr[7] = s7;
+    arr[8] = s8;
+    arr[9] = s9;
+}
+
 #else
 
 #error "Architecture not supported for gc_helper_get_regs. Set MICROPY_GCREGS_SETJMP to use the fallback implementation."
diff --git a/shared/runtime/gchelper_loong64.s b/shared/runtime/gchelper_loong64.s
@@ -0,0 +1,50 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2026 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.
+ */
+
+    .global gc_helper_get_regs_and_sp
+    .type   gc_helper_get_regs_and_sp, @function
+
+gc_helper_get_regs_and_sp:
+
+    /* Store registers into the given array. */
+
+    st.d  $r23, $r4, 0   /* Save S0.  */
+    st.d  $r24, $r4, 8   /* Save S1.  */
+    st.d  $r25, $r4, 16  /* Save S2.  */
+    st.d  $r26, $r4, 24  /* Save S3.  */
+    st.d  $r27, $r4, 32  /* Save S4.  */
+    st.d  $r28, $r4, 40  /* Save S5.  */
+    st.d  $r29, $r4, 48  /* Save S6.  */
+    st.d  $r30, $r4, 56  /* Save S7.  */
+    st.d  $r31, $r4, 64  /* Save S8.  */
+    st.d  $r22, $r4, 72  /* Save S9.  */
+
+    /* Return the stack pointer. */
+
+    add.d $r4, $r0, $r3
+    jirl  $r0, $r1, 0
+
+    .size gc_helper_get_regs_and_sp, .-gc_helper_get_regs_and_sp
