diff options
| -rw-r--r-- | gcc/ChangeLog | 4 | ||||
| -rw-r--r-- | gcc/flow.c | 46 |
2 files changed, 48 insertions, 2 deletions
diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 0a7843b..a7e32fa 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,7 @@ +Sat Mar 27 16:13:50 1999 Jeffrey A Law (law@cygnus.com) + + * flow.c (mark_used_regs): Improve handling of ASMs. + 1999-03-26 Zack Weinberg <zack@rabi.columbia.edu> * Makefile.in (xcpp, cppspec.o): New targets. @@ -242,7 +242,12 @@ static int loop_depth; static int cc0_live; /* During propagate_block, this contains a list of all the MEMs we are - tracking for dead store elimination. */ + tracking for dead store elimination. + + ?!? Note we leak memory by not free-ing items on this list. We need to + write some generic routines to operate on memory lists since cse, gcse, + loop, sched, flow and possibly other passes all need to do basically the + same operations on these lists. */ static rtx mem_set_list; @@ -3593,7 +3598,6 @@ mark_used_regs (needed, live, x, final, insn) case PC: case ADDR_VEC: case ADDR_DIFF_VEC: - case ASM_INPUT: return; #ifdef HAVE_cc0 @@ -3908,6 +3912,44 @@ mark_used_regs (needed, live, x, final, insn) SET_REGNO_REG_SET (live, i); break; + case ASM_OPERANDS: + case UNSPEC_VOLATILE: + case TRAP_IF: + case ASM_INPUT: + { + /* Traditional and volatile asm instructions must be considered to use + and clobber all hard registers, all pseudo-registers and all of + memory. So must TRAP_IF and UNSPEC_VOLATILE operations. + + Consider for instance a volatile asm that changes the fpu rounding + mode. An insn should not be moved across this even if it only uses + pseudo-regs because it might give an incorrectly rounded result. + + ?!? Unfortunately, marking all hard registers as live causes massive + problems for the register allocator and marking all pseudos as live + creates mountains of uninitialized variable warnings. + + So for now, just clear the memory set list and mark any regs + we can find in ASM_OPERANDS as used. */ + if (code != ASM_OPERANDS || MEM_VOLATILE_P (x)) + mem_set_list = NULL_RTX; + + /* For all ASM_OPERANDS, we must traverse the vector of input operands. + We can not just fall through here since then we would be confused + by the ASM_INPUT rtx inside ASM_OPERANDS, which do not indicate + traditional asms unlike their normal usage. */ + if (code == ASM_OPERANDS) + { + int j; + + for (j = 0; j < ASM_OPERANDS_INPUT_LENGTH (x); j++) + mark_used_regs (needed, live, ASM_OPERANDS_INPUT (x, j), + final, insn); + } + break; + } + + default: break; } |