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middle-end: extend the narrower shift amount before broadcasting it [PR 124250]

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The comment above expand_vector_broadcast() states a precondition that
the mode of op must be the element mode of vmode.  But when
expand_binop() called expand_vector_broadcast() to broadcast the shift
amount, it only truncated the shift amount if it's too wide, but no
action is performed if the shift amount is too narrow.

	PR middle-end/124250
	PR target/123807

gcc/
	* optabs.cc (expand_vector_broadcast): Add a checking assert to
	verify the precondition about the input modes.
	(expand_binop): Extend the shift amount if it's narrower than
	the element of the shifted vector.

gcc/testsuite/

	* gcc.c-torture/compile/pr124250.c: New test.
This commit is contained in:
Xi Ruoyao
2026-02-26 11:55:22 +08:00
parent 1c842aa818
commit 1139fdadc8
2 changed files with 31 additions and 11 deletions
Download Patch File Download Diff File Expand all files Collapse all files

34
gcc/optabs.cc
View File

@@ -428,9 +428,9 @@ force_expand_binop (machine_mode mode, optab binoptab,
return true;
}
/* Create a new vector value in VMODE with all elements set to OP. The
mode of OP must be the element mode of VMODE. If OP is a constant,
then the return value will be a constant. */
/* Create a new vector value in VMODE with all elements set to OP. If OP
is not a constant, the mode of it must be the element mode of VMODE.
If OP is a constant, then the return value will be a constant. */
rtx
expand_vector_broadcast (machine_mode vmode, rtx op)
@@ -439,6 +439,8 @@ expand_vector_broadcast (machine_mode vmode, rtx op)
rtvec vec;
gcc_checking_assert (VECTOR_MODE_P (vmode));
gcc_checking_assert (CONST_INT_P (op)
|| GET_MODE_INNER (vmode) == GET_MODE (op));
if (valid_for_const_vector_p (vmode, op))
return gen_const_vec_duplicate (vmode, op);
@@ -1629,15 +1631,25 @@ expand_binop (machine_mode mode, optab binoptab, rtx op0, rtx op1,
if (otheroptab
&& (icode = optab_handler (otheroptab, mode)) != CODE_FOR_nothing)
{
/* The scalar may have been extended to be too wide. Truncate
it back to the proper size to fit in the broadcast vector. */
/* The scalar may be wider or narrower than the vector element.
Truncate or extend it to the proper size to fit in the
broadcast vector. */
scalar_mode inner_mode = GET_MODE_INNER (mode);
if (!CONST_INT_P (op1)
&& (GET_MODE_BITSIZE (as_a <scalar_int_mode> (GET_MODE (op1)))
> GET_MODE_BITSIZE (inner_mode)))
op1 = force_reg (inner_mode,
simplify_gen_unary (TRUNCATE, inner_mode, op1,
GET_MODE (op1)));
if (!CONST_INT_P (op1))
{
auto mode1 = as_a <scalar_int_mode> (GET_MODE (op1));
int size1 = GET_MODE_BITSIZE (mode1);
int inner_size = GET_MODE_BITSIZE (inner_mode);
if (size1 != inner_size)
{
auto unary = size1 > inner_size ? TRUNCATE : ZERO_EXTEND;
op1 = force_reg (inner_mode,
simplify_gen_unary (unary, inner_mode,
op1, mode1));
}
}
rtx vop1 = expand_vector_broadcast (mode, op1);
if (vop1)
{

8
gcc/testsuite/gcc.c-torture/compile/pr124250.c Normal file
View File

@@ -0,0 +1,8 @@
typedef long long v2i64 __attribute__ ((vector_size (16), aligned (16)));
v2i64 a, b;
void
test (int l)
{
a = b >> (-l);
}