mirror/gcc
2
0
Fork 0
mirror of git://gcc.gnu.org/git/gcc.git synced 2024-12-30 07:54:42 +08:00
Code Issues Packages Projects Releases Wiki Activity

sparc.h (REG_ALLOC_ORDER, [...]): Tweak, and add more detailed comments.

Browse Source 
2002-05-03  David S. Miller  <davem@redhat.com>

	* config/sparc/sparc.h (REG_ALLOC_ORDER, REG_LEAF_ALLOC_ORDER):
	Tweak, and add more detailed comments.

From-SVN: r53144
This commit is contained in:
David S. Miller 2002-05-03 21:21:46 -07:00 committed by David S. Miller
parent 1c177c1816
commit af54350e17
2 changed files with 65 additions and 27 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
gcc/ChangeLog
View File

@ -1,3 +1,8 @@
2002-05-03 David S. Miller <davem@redhat.com>
* config/sparc/sparc.h (REG_ALLOC_ORDER, REG_LEAF_ALLOC_ORDER):
Tweak, and add more detailed comments.
2002-05-03 Zack Weinberg <zack@codesourcery.com>
* Re-apply patch accidentally reverted with

87
gcc/config/sparc/sparc.h
View File

@ -1273,16 +1273,31 @@ extern enum reg_class sparc_regno_reg_class[FIRST_PSEUDO_REGISTER];
/* This is the order in which to allocate registers normally.
We put %f0/%f1 last among the float registers, so as to make it more
We put %f0-%f7 last among the float registers, so as to make it more
likely that a pseudo-register which dies in the float return register
will get allocated to the float return register, thus saving a move
instruction at the end of the function. */
area will get allocated to the float return register, thus saving a move
instruction at the end of the function.
Similarly for integer return value registers.
We know in this case that we will not end up with a leaf function.
The register allocater is given the global and out registers first
because these registers are call clobbered and thus less useful to
global register allocation.
Next we list the local and in registers. They are not call clobbered
and thus very useful for global register allocation. We list the input
registers before the locals so that it is more likely the incoming
arguments received in those registers can just stay there and not be
reloaded. */
#define REG_ALLOC_ORDER \
{ 8, 9, 10, 11, 12, 13, 2, 3, \
15, 16, 17, 18, 19, 20, 21, 22, \
23, 24, 25, 26, 27, 28, 29, 31, \
34, 35, 36, 37, 38, 39, /* %f2-%f7 */ \
{ 1, 2, 3, 4, 5, 6, 7, /* %g1-%g7 */ \
13, 12, 11, 10, 9, 8, /* %o5-%o0 */ \
15, /* %o7 */ \
16, 17, 18, 19, 20, 21, 22, 23, /* %l0-%l7 */ \
29, 28, 27, 26, 25, 24, 31, /* %i5-%i0,%i7 */\
40, 41, 42, 43, 44, 45, 46, 47, /* %f8-%f15 */ \
48, 49, 50, 51, 52, 53, 54, 55, /* %f16-%f23 */ \
56, 57, 58, 59, 60, 61, 62, 63, /* %f24-%f31 */ \
@ -1290,30 +1305,48 @@ extern enum reg_class sparc_regno_reg_class[FIRST_PSEUDO_REGISTER];
72, 73, 74, 75, 76, 77, 78, 79, /* %f40-%f47 */ \
80, 81, 82, 83, 84, 85, 86, 87, /* %f48-%f55 */ \
88, 89, 90, 91, 92, 93, 94, 95, /* %f56-%f63 */ \
32, 33, /* %f0,%f1 */ \
96, 97, 98, 99, 100, /* %fcc0-3, %icc */ \
1, 4, 5, 6, 7, 0, 14, 30, 101}
39, 38, 37, 36, 35, 34, 33, 32, /* %f7-%f0 */ \
96, 97, 98, 99, /* %fcc0-3 */ \
100, 0, 14, 30, 101} /* %icc, %g0, %o6, %i6, %sfp */
/* This is the order in which to allocate registers for
leaf functions. If all registers can fit in the "gi" registers,
then we have the possibility of having a leaf function. */
leaf functions. If all registers can fit in the global and
output registers, then we have the possibility of having a leaf
function.
The macro actually mentioned the input registers first,
because they get renumbered into the output registers once
we know really do have a leaf function.
To be more precise, this register allocation order is used
when %o7 is found to not be clobbered right before register
allocation. Normally, the reason %o7 would be clobbered is
due to a call which could not be transformed into a sibling
call.
As a consequence, it is possible to use the leaf register
allocation order and not end up with a leaf function. We will
not get suboptimal register allocation in that case because by
definition of being potentially leaf, there were no function
calls. Therefore, allocation order within the local register
window is not critical like it is when we do have function calls. */
#define REG_LEAF_ALLOC_ORDER \
{ 2, 3, 24, 25, 26, 27, 28, 29, \
4, 5, 6, 7, 1, \
15, 8, 9, 10, 11, 12, 13, \
16, 17, 18, 19, 20, 21, 22, 23, \
34, 35, 36, 37, 38, 39, \
40, 41, 42, 43, 44, 45, 46, 47, \
48, 49, 50, 51, 52, 53, 54, 55, \
56, 57, 58, 59, 60, 61, 62, 63, \
64, 65, 66, 67, 68, 69, 70, 71, \
72, 73, 74, 75, 76, 77, 78, 79, \
80, 81, 82, 83, 84, 85, 86, 87, \
88, 89, 90, 91, 92, 93, 94, 95, \
32, 33, \
96, 97, 98, 99, 100, \
0, 14, 30, 31, 101}
{ 1, 2, 3, 4, 5, 6, 7, /* %g1-%g7 */ \
29, 28, 27, 26, 25, 24, /* %i5-%i0 */ \
15, /* %o7 */ \
13, 12, 11, 10, 9, 8, /* %o5-%o0 */ \
16, 17, 18, 19, 20, 21, 22, 23, /* %l0-%l7 */ \
40, 41, 42, 43, 44, 45, 46, 47, /* %f8-%f15 */ \
48, 49, 50, 51, 52, 53, 54, 55, /* %f16-%f23 */ \
56, 57, 58, 59, 60, 61, 62, 63, /* %f24-%f31 */ \
64, 65, 66, 67, 68, 69, 70, 71, /* %f32-%f39 */ \
72, 73, 74, 75, 76, 77, 78, 79, /* %f40-%f47 */ \
80, 81, 82, 83, 84, 85, 86, 87, /* %f48-%f55 */ \
88, 89, 90, 91, 92, 93, 94, 95, /* %f56-%f63 */ \
39, 38, 37, 36, 35, 34, 33, 32, /* %f7-%f0 */ \
96, 97, 98, 99, /* %fcc0-3 */ \
100, 0, 14, 30, 31, 101} /* %icc, %g0, %o6, %i6, %i7, %sfp */
#define ORDER_REGS_FOR_LOCAL_ALLOC order_regs_for_local_alloc ()