arm-gen.c: support VLAs

1 files changed, 23 insertions, 3 deletions

diff --git a/arm-gen.c b/arm-gen.c
index 3dcc6f9..cb2b19a 100644
--- a/arm-gen.c
+++ b/arm-gen.c
@@ -2122,17 +2122,37 @@ void ggoto(void)
 
 /* Save the stack pointer onto the stack and return the location of its address */
 ST_FUNC void gen_vla_sp_save(int addr) {
-    tcc_error("variable length arrays unsupported for this target");
+    SValue v;
+    v.type.t = VT_PTR;
+    v.r = VT_LOCAL | VT_LVAL;
+    v.c.i = addr;
+    store(TREG_SP, &v);
 }
 
 /* Restore the SP from a location on the stack */
 ST_FUNC void gen_vla_sp_restore(int addr) {
-    tcc_error("variable length arrays unsupported for this target");
+    SValue v;
+    v.type.t = VT_PTR;
+    v.r = VT_LOCAL | VT_LVAL;
+    v.c.i = addr;
+    load(TREG_SP, &v);
 }
 
 /* Subtract from the stack pointer, and push the resulting value onto the stack */
 ST_FUNC void gen_vla_alloc(CType *type, int align) {
-    tcc_error("variable length arrays unsupported for this target");
+    int r = intr(gv(RC_INT));
+    o(0xE04D0000|(r<<12)|r); /* sub r, sp, r */
+#ifdef TCC_ARM_EABI
+    if (align < 8)
+        align = 8;
+#else
+    if (align < 4)
+        align = 4;
+#endif
+    if (align & (align - 1))
+        tcc_error("alignment is not a power of 2: %i", align);
+    o(stuff_const(0xE3C0D000|(r<<16), align - 1)); /* bic sp, r, #align-1 */
+    vpop();
 }
 
 /* end of ARM code generator */