1 files changed, 39 insertions, 0 deletions
diff --git a/i386-gen.c b/i386-gen.c
index 044f9e6..9ff2e18 100644
--- a/i386-gen.c
+++ b/i386-gen.c
@@ -43,6 +43,7 @@ enum {
     TREG_ECX,
     TREG_EDX,
     TREG_ST0,
+    TREG_ESP = 4
 };
 
 /* return registers for function */
@@ -1117,6 +1118,44 @@ ST_FUNC void gen_bounded_ptr_deref(void)
 }
 #endif
 
+/* Save the stack pointer onto the stack */
+ST_FUNC void gen_vla_sp_save(int addr) {
+    /* mov %esp,addr(%ebp)*/
+    o(0x89);
+    gen_modrm(TREG_ESP, VT_LOCAL, NULL, addr);
+}
+
+/* Restore the SP from a location on the stack */
+ST_FUNC void gen_vla_sp_restore(int addr) {
+    o(0x8b);
+    gen_modrm(TREG_ESP, VT_LOCAL, NULL, addr);
+}
+
+/* Subtract from the stack pointer, and push the resulting value onto the stack */
+ST_FUNC void gen_vla_alloc(CType *type, int align) {
+#ifdef TCC_TARGET_PE
+    /* alloca does more than just adjust %rsp on Windows */
+    vpush_global_sym(&func_old_type, TOK_alloca);
+    vswap(); /* Move alloca ref past allocation size */
+    gfunc_call(1);
+    vset(type, REG_IRET, 0);
+#else
+    int r;
+    r = gv(RC_INT); /* allocation size */
+    /* sub r,%rsp */
+    o(0x2b);
+    o(0xe0 | r);
+    /* We align to 16 bytes rather than align */
+    /* and ~15, %esp */
+    o(0xf0e483);
+    /* mov %esp, r */
+    o(0x89);
+    o(0xe0 | r);
+    vpop();
+    vset(type, r, 0);
+#endif
+}
+
 /* end of X86 code generator */
 /*************************************************************/
 #endif