This is Richi's prototype patch in
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=36043#c23 with fixes for
blocks larger than one reg, big-endian, and BLOCK_REG_PADDING.
I also removed the operand_subword_force since we may as well let
narrow_bit_field_mem in extract_bit_field do that for us. It is
necessary to do the BLOCK_REG_PADDING shift after we've loaded the
block or else repeat the bit-field extraction in that case.
Bootstrapped and regression tested (-m32 and -m64) x86_64-linux and
powerpc64-linux. OK to apply?
I'll also throw together a testcase or three. For execute tests I'm
thinking of using sbrk to locate an odd sized struct such that access
past the end segfaults, rather than mmap/munmap as was done in the
pr36043 testcase. Does that sound reasonable?
PR target/65408
PR target/58744
PR middle-end/36043
* calls.c (load_register_parameters): Don't load past end of
mem unless suitably aligned.
Index: gcc/calls.c
===================================================================
--- gcc/calls.c (revision 221435)
+++ gcc/calls.c (working copy)
@@ -2090,6 +2090,26 @@ load_register_parameters (struct arg_data *args, i
(XEXP (args[i].value, 0), size)))
*sibcall_failure = 1;
+ if (size % UNITS_PER_WORD == 0
+ || MEM_ALIGN (mem) % BITS_PER_WORD == 0)
+ move_block_to_reg (REGNO (reg), mem, nregs, args[i].mode);
+ else
+ {
+ if (nregs > 1)
+ move_block_to_reg (REGNO (reg), mem, nregs - 1,
+ args[i].mode);
+ rtx dest = gen_rtx_REG (word_mode, REGNO (reg) + nregs - 1);
+ unsigned int bitoff = (nregs - 1) * BITS_PER_WORD;
+ unsigned int bitsize = size * BITS_PER_UNIT - bitoff;
+ rtx x = extract_bit_field (mem, bitsize, bitoff, 1,
+ dest, word_mode, word_mode);
+ if (BYTES_BIG_ENDIAN)
+ x = expand_shift (LSHIFT_EXPR, word_mode, x,
+ BITS_PER_WORD - bitsize, dest, 1);
+ if (x != dest)
+ emit_move_insn (dest, x);
+ }
+
/* Handle a BLKmode that needs shifting. */
if (nregs == 1 && size < UNITS_PER_WORD
#ifdef BLOCK_REG_PADDING
@@ -2097,22 +2117,18 @@ load_register_parameters (struct arg_data *args, i
#else
&& BYTES_BIG_ENDIAN
#endif
- )
+ )
{
- rtx tem = operand_subword_force (mem, 0, args[i].mode);
- rtx ri = gen_rtx_REG (word_mode, REGNO (reg));
- rtx x = gen_reg_rtx (word_mode);
+ rtx dest = gen_rtx_REG (word_mode, REGNO (reg));
int shift = (UNITS_PER_WORD - size) * BITS_PER_UNIT;
- enum tree_code dir = BYTES_BIG_ENDIAN ? RSHIFT_EXPR
- : LSHIFT_EXPR;
+ enum tree_code dir = (BYTES_BIG_ENDIAN
+ ? RSHIFT_EXPR : LSHIFT_EXPR);
+ rtx x;
- emit_move_insn (x, tem);
- x = expand_shift (dir, word_mode, x, shift, ri, 1);
- if (x != ri)
- emit_move_insn (ri, x);
+ x = expand_shift (dir, word_mode, dest, shift, dest, 1);
+ if (x != dest)
+ emit_move_insn (dest, x);
}
- else
- move_block_to_reg (REGNO (reg), mem, nregs, args[i].mode);
}
/* When a parameter is a block, and perhaps in other cases, it is
--
Alan Modra
Australia Development Lab, IBM
