Make the banked call routine an ASM callback leaf.

This allows the norecurse pass to effectively see through it.
llvm-mos · Oct 8, 2022 · 79f20a5 · 79f20a5
1 parent 4d03950
commit 79f20a5
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Showing 3 changed files with 19 additions and 9 deletions.
diff --git a/mos-platform/nes-mmc1/bank.c b/mos-platform/nes-mmc1/bank.c
@@ -79,14 +79,6 @@ mmc1_register_write_retry(unsigned addr, char val) {
   _IN_PROGRESS = 0;
 }
 
-__attribute__((noinline, weak)) void banked_call(char bank_id,
-                                                 void (*method)(void)) {
-  char old_id = get_prg_bank();
-  set_prg_bank(bank_id);
-  method();
-  set_prg_bank(old_id);
-}
-
 __attribute__((weak)) void set_chr_bank_0(char bank_id) {
   _CHR_BANK0 = bank_id;
 }

diff --git a/mos-platform/nes-mmc1/bank.h b/mos-platform/nes-mmc1/bank.h
@@ -44,7 +44,7 @@ extern volatile const char MMC1_CTRL_CUR;
 // Switch to another bank and call this function.
 // Note: Using banked_call to call a second function from within
 // another banked_call is safe.
-void banked_call(char bank_id, void (*method)(void));
+__attribute__((leaf, callback(2))) void banked_call(char bank_id, void (*method)(void));
 
 // Switch to the given bank (to $8000-bfff). Your prior bank is not saved.
 // Can be used for reading data with a function in the fixed bank.

diff --git a/mos-platform/nes-mmc1/bank.s b/mos-platform/nes-mmc1/bank.s
@@ -86,3 +86,21 @@ set_prg_bank:
 	tya
 	jmp .Lset
 
+
+
+.section .text.banked_call,"ax",@progbits
+.weak banked_call
+banked_call:
+	tay
+	lda _PRG_BANK
+	pha
+	tya
+	jsr __set_prg_bank
+	lda mos8(__rc2)
+	sta mos8(__rc18)
+	lda mos8(__rc3)
+	sta mos8(__rc19)
+	jsr __call_indir
+	pla
+	jsr __set_prg_bank
+	rts