There are (4) basic forms that are matched:
+ (1) FORM_PRE_ADD
a <- b + c
...
*a
a <- b
...
*(a += c) pre
+
+
+ (2) FORM_PRE_INC
a += c
...
*a
becomes
*(a += c) pre
+
+
+ (3) FORM_POST_ADD
*a
...
b <- a + c
- for this case to be true, b must not be assigned or used between
- the *a and the assignment to b. B must also be a Pmode reg.
+ (For this case to be true, b must not be assigned or used between
+ the *a and the assignment to b. B must also be a Pmode reg.)
becomes
b <- a
...
*(b += c) post
+
+
+ (4) FORM_POST_INC
*a
...
a <- a + c
The is one special case: if a already had an offset equal to it +-
its width and that offset is equal to -c when the increment was
before the ref or +c if the increment was after the ref, then if we
- can do the combination but switch the pre/post bit.
-
- (1) FORM_PRE_ADD
-
- a <- b + c
- ...
- *(a - c)
-
- becomes
-
- a <- b
- ...
- *(a += c) post
-
- (2) FORM_PRE_INC
-
- a += c
- ...
- *(a - c)
-
- becomes
-
- *(a += c) post
+ can do the combination but switch the pre/post bit. */
- (3) FORM_POST_ADD
-
- *(a + c)
- ...
- b <- a + c
-
- for this case to be true, b must not be assigned or used between
- the *a and the assignment to b. B must also be a Pmode reg.
-
- becomes
-
- b <- a
- ...
- *(b += c) pre
-
-
- (4) FORM_POST_INC
-
- *(a + c)
- ...
- a <- a + c
-
- becomes
-
- *(a += c) pre
-*/
#ifdef AUTO_INC_DEC
enum form