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* flow.c (mark_used_regs): Improve handling of ASMs.

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From-SVN: r26014
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Jeffrey A Law 1999-03-27 15:18:32 +00:00 committed by Jeff Law
parent 26f096f9e5
commit 40b5a77c50
2 changed files with 48 additions and 2 deletions
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4
gcc/ChangeLog
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@ -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.

46
gcc/flow.c
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@ -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;
}