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Be stricter about CONST_VECTOR operands
- From: Richard Sandiford <richard dot sandiford at linaro dot org>
- To: gcc-patches at gcc dot gnu dot org
- Date: Mon, 06 Nov 2017 09:10:23 +0000
- Subject: Be stricter about CONST_VECTOR operands
- Authentication-results: sourceware.org; auth=none
The recent gen_vec_duplicate patches used CONST_VECTOR for all
constants, but the documentation says:
@findex const_vector
@item (const_vector:@var{m} [@var{x0} @var{x1} @dots{}])
Represents a vector constant. The square brackets stand for the vector
containing the constant elements. @var{x0}, @var{x1} and so on are
the @code{const_int}, @code{const_double} or @code{const_fixed} elements.
Both the AArch32 and AArch64 ports relied on the elements having
this form and would ICE if the element was something like a CONST
instead. This showed up as a failure in vect-102.c for both arm-eabi
and aarch64-elf (but not aarch64-linux-gnu, which is what the series
was tested on).
The two obvious options were to redefine CONST_VECTOR to accept all
constants or make gen_vec_duplicate honour the existing documentation.
It looks like other code also assumes that integer CONST_VECTORs contain
CONST_INTs, so the patch does the latter.
I deliberately didn't add an assert to gen_const_vec_duplicate
because it looks like the SPU port *does* expect to be able to create
CONST_VECTORs of symbolic constants.
Also, I think the list above should include const_wide_int for vectors
of TImode and wider.
The new routine takes a mode for consistency with the generators,
and because I think it does make sense to accept all constants for
variable-length:
(const (vec_duplicate ...))
rather than have some rtxes for which we instead use:
(vec_duplicate (const ...))
Tested on aarch64-elf, aarch64-linux-gnu, x86_64-linux-gnu and
powerpc64-linux-gnu. OK to install?
Richard
2017-11-06 Richard Sandiford <richard.sandiford@linaro.org>
gcc/
* doc/rtl.texi (const_vector): Say that elements can be
const_wide_ints too.
* emit-rtl.h (valid_for_const_vec_duplicate_p): Declare.
* emit-rtl.c (valid_for_const_vec_duplicate_p): New function.
(gen_vec_duplicate): Use it instead of CONSTANT_P.
* optabs.c (expand_vector_broadcast): Likewise.
Index: gcc/doc/rtl.texi
===================================================================
--- gcc/doc/rtl.texi 2017-11-06 08:56:27.608223621 +0000
+++ gcc/doc/rtl.texi 2017-11-06 09:01:44.150672938 +0000
@@ -1625,7 +1625,8 @@ accessed with @code{CONST_FIXED_VALUE_LO
@item (const_vector:@var{m} [@var{x0} @var{x1} @dots{}])
Represents a vector constant. The square brackets stand for the vector
containing the constant elements. @var{x0}, @var{x1} and so on are
-the @code{const_int}, @code{const_double} or @code{const_fixed} elements.
+the @code{const_int}, @code{const_wide_int}, @code{const_double} or
+@code{const_fixed} elements.
The number of units in a @code{const_vector} is obtained with the macro
@code{CONST_VECTOR_NUNITS} as in @code{CONST_VECTOR_NUNITS (@var{v})}.
Index: gcc/emit-rtl.h
===================================================================
--- gcc/emit-rtl.h 2017-11-06 08:56:27.157323659 +0000
+++ gcc/emit-rtl.h 2017-11-06 09:01:44.151672938 +0000
@@ -438,6 +438,7 @@ get_max_uid (void)
return crtl->emit.x_cur_insn_uid;
}
+extern bool valid_for_const_vec_duplicate_p (machine_mode, rtx);
extern rtx gen_const_vec_duplicate (machine_mode, rtx);
extern rtx gen_vec_duplicate (machine_mode, rtx);
Index: gcc/emit-rtl.c
===================================================================
--- gcc/emit-rtl.c 2017-11-06 08:56:27.608223621 +0000
+++ gcc/emit-rtl.c 2017-11-06 09:01:44.151672938 +0000
@@ -5757,6 +5757,17 @@ init_emit (void)
#endif
}
+/* Return true if X is a valid element for a duplicated vector constant
+ of the given mode. */
+
+bool
+valid_for_const_vec_duplicate_p (machine_mode, rtx x)
+{
+ return (CONST_SCALAR_INT_P (x)
+ || CONST_DOUBLE_AS_FLOAT_P (x)
+ || CONST_FIXED_P (x));
+}
+
/* Like gen_const_vec_duplicate, but ignore const_tiny_rtx. */
static rtx
@@ -5792,7 +5803,7 @@ gen_const_vec_duplicate (machine_mode mo
rtx
gen_vec_duplicate (machine_mode mode, rtx x)
{
- if (CONSTANT_P (x))
+ if (valid_for_const_vec_duplicate_p (mode, x))
return gen_const_vec_duplicate (mode, x);
return gen_rtx_VEC_DUPLICATE (mode, x);
}
Index: gcc/optabs.c
===================================================================
--- gcc/optabs.c 2017-11-06 08:56:27.466923633 +0000
+++ gcc/optabs.c 2017-11-06 09:01:44.152672938 +0000
@@ -377,7 +377,7 @@ expand_vector_broadcast (machine_mode vm
gcc_checking_assert (VECTOR_MODE_P (vmode));
- if (CONSTANT_P (op))
+ if (valid_for_const_vec_duplicate_p (vmode, op))
return gen_const_vec_duplicate (vmode, op);
/* ??? If the target doesn't have a vec_init, then we have no easy way