Hi,
For following test-case:
typedef double v4df __attribute__ ((vector_size (32)));
void foo(v4df);
int
main ()
{
volatile v4df x1;
x1 = (v4df) { 10.0, 20.0, 30.0, 40.0 };
foo (x1);
return 0;
}
Compiling with -msve-vector-bits=256, the compiler goes into infinite
recursion and eventually segfaults due to stack overflow.
This happens during expansion of:
x1.0_1 ={v} x1;
aarch64_expand_sve_mem_move calls aarch64_emit_sve_pred_move with
dest = (reg:VNx2DF 93) and
src = (mem/u/c:VNx2DF
(plus:DI (reg/f:DI 94) (const_int 32 [0x20])) [0 S32 A128])
aarch64_emit_sve_pred_move calls expand_insn with above ops.
Eventually we hit EXPAND_INPUT case in maybe_legitimize_operand for
src (opno == 2)
Since the operand is marked with volatile, and volatile_ok is set to false,
insn_operand_matches return false and we call:
op->value = copy_to_mode_reg (mode, op->value);
break;
copy_to_mode_reg however, creates a fresh register and calls emit_move_insn:
rtx temp = gen_reg_rtx (mode);
if (x != temp)
emit_move_insn (temp, x);
and we again end up in aarch64_emit_sve_pred_move, with dest assigned
the new register and src remaining unchanged, and thus the cycle continues.
As suggested by Richard, the attached patch temporarily sets volatile_ok to true
using RAII class volatile_ok_temp in aarch64_emit_sve_pred_move which
avoids the recursion.
Bootstrap + tested on x86_64-unknown-linux-gnu, aarch64-linux-gnu.
Cross-testing with SVE in progress.
OK to commit ?
Thanks,
Prathamesh
2019-07-09 Prathamesh Kulkarni <prathamesh.kulka...@linaro.org>
PR target/90723
* recog.h (volatile_ok_temp): New class.
* config/aarch64/aarch64.c (aarch64_emit_sve_pred_move): Set
volatile_ok temporarily to true using volatile_ok_temp.
* expr.c (emit_block_move_via_cpymem): Likewise.
* optabs.c (maybe_legitimize_operand): Likewise.
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 5a923ca006b..50afba1a2b6 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -3457,6 +3457,7 @@ aarch64_emit_sve_pred_move (rtx dest, rtx pred, rtx src)
create_output_operand (&ops[0], dest, mode);
create_input_operand (&ops[1], pred, GET_MODE(pred));
create_input_operand (&ops[2], src, mode);
+ volatile_ok_temp v(true);
expand_insn (code_for_aarch64_pred_mov (mode), 3, ops);
}
diff --git a/gcc/expr.c b/gcc/expr.c
index 4acf250dd3c..87720875864 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -1732,8 +1732,6 @@ emit_block_move_via_cpymem (rtx x, rtx y, rtx size,
unsigned int align,
unsigned HOST_WIDE_INT max_size,
unsigned HOST_WIDE_INT probable_max_size)
{
- int save_volatile_ok = volatile_ok;
-
if (expected_align < align)
expected_align = align;
if (expected_size != -1)
@@ -1745,7 +1743,7 @@ emit_block_move_via_cpymem (rtx x, rtx y, rtx size,
unsigned int align,
}
/* Since this is a move insn, we don't care about volatility. */
- volatile_ok = 1;
+ volatile_ok_temp v(true);
/* Try the most limited insn first, because there's no point
including more than one in the machine description unless
@@ -1809,14 +1807,10 @@ emit_block_move_via_cpymem (rtx x, rtx y, rtx size,
unsigned int align,
create_fixed_operand (&ops[8], NULL);
}
if (maybe_expand_insn (code, nops, ops))
- {
- volatile_ok = save_volatile_ok;
- return true;
- }
+ return true;
}
}
- volatile_ok = save_volatile_ok;
return false;
}
diff --git a/gcc/optabs.c b/gcc/optabs.c
index 18ca7370917..1959087b7b3 100644
--- a/gcc/optabs.c
+++ b/gcc/optabs.c
@@ -7202,17 +7202,15 @@ maybe_legitimize_operand (enum insn_code icode,
unsigned int opno,
struct expand_operand *op)
{
machine_mode mode, imode;
- bool old_volatile_ok, result;
mode = op->mode;
switch (op->type)
{
case EXPAND_FIXED:
- old_volatile_ok = volatile_ok;
- volatile_ok = true;
- result = maybe_legitimize_operand_same_code (icode, opno, op);
- volatile_ok = old_volatile_ok;
- return result;
+ {
+ volatile_ok_temp v(true);
+ return maybe_legitimize_operand_same_code (icode, opno, op);
+ }
case EXPAND_OUTPUT:
gcc_assert (mode != VOIDmode);
diff --git a/gcc/recog.h b/gcc/recog.h
index 75cbbdc10ad..8a8eaf7e0c3 100644
--- a/gcc/recog.h
+++ b/gcc/recog.h
@@ -186,6 +186,22 @@ skip_alternative (const char *p)
/* Nonzero means volatile operands are recognized. */
extern int volatile_ok;
+/* RAII class for temporarily setting volatile_ok. */
+
+class volatile_ok_temp
+{
+public:
+ volatile_ok_temp(int value): save_volatile_ok (volatile_ok)
+ {
+ volatile_ok = value;
+ }
+
+ ~volatile_ok_temp() { volatile_ok = save_volatile_ok; }
+
+private:
+ int save_volatile_ok;
+};
+
/* Set by constrain_operands to the number of the alternative that
matched. */
extern int which_alternative;
