diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ChangeLog | 5 | ||||
| -rw-r--r-- | gcc/config/sparc/sparc.h | 87 |
2 files changed, 65 insertions, 27 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index e3a5030..7d88765 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -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 diff --git a/gcc/config/sparc/sparc.h b/gcc/config/sparc/sparc.h index f582b6a..f807be8 100644 --- a/gcc/config/sparc/sparc.h +++ b/gcc/config/sparc/sparc.h @@ -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 () |