[PATCH] Handle CONST_POLY_INTs in CONST_VECTORs [PR97141, PR98726]
Richard Sandiford
richard.sandiford@arm.com
Wed Mar 31 10:24:18 GMT 2021
This PR is caused by POLY_INT_CSTs being (necessarily) valid
in tree-level VECTOR_CSTs but CONST_POLY_INTs not being valid
in RTL CONST_VECTORs. I can't tell/remember how deliberate
that was, but I'm guessing not very. In particular,
valid_for_const_vector_p was added to guard against symbolic
constants rather than CONST_POLY_INTs.
I did briefly consider whether we should maintain the current
status anyway. However, that would then require a way of
constructing variable-length vectors from individiual elements
if, say, we have:
{ [2, 2], [3, 2], [4, 2], … }
So I'm chalking this up to an oversight. I think the intention
(and certainly the natural thing) is to have the same rules for
both trees and RTL.
The SVE CONST_VECTOR code should already be set up to handle
CONST_POLY_INTs. However, we need to add support for Advanced SIMD
CONST_VECTORs that happen to contain SVE-based values. The patch does
that by expanding such CONST_VECTORs in the same way as variable vectors.
Tested on aarch64-linux-gnu, armeb-eabi and x86_64-linux-gnu.
OK for the target-independent bits?
Richard
gcc/
PR rtl-optimization/97141
PR rtl-optimization/98726
* emit-rtl.c (valid_for_const_vector_p): Return true for
CONST_POLY_INT_P.
* rtx-vector-builder.h (rtx_vector_builder::step): Return a
poly_wide_int instead of a wide_int.
(rtx_vector_builder::apply_set): Take a poly_wide_int instead
of a wide_int.
* rtx-vector-builder.c (rtx_vector_builder::apply_set): Likewise.
* config/aarch64/aarch64.c (aarch64_legitimate_constant_p): Return
false for CONST_VECTORs that cannot be forced to memory.
* config/aarch64/aarch64-simd.md (mov<mode>): If a CONST_VECTOR
is too complex to force to memory, build it up from individual
elements instead.
gcc/testsuite/
PR rtl-optimization/97141
PR rtl-optimization/98726
* gcc.c-torture/compile/pr97141.c: New test.
* gcc.c-torture/compile/pr98726.c: Likewise.
* gcc.target/aarch64/sve/pr97141.c: Likewise.
* gcc.target/aarch64/sve/pr98726.c: Likewise.
---
gcc/config/aarch64/aarch64-simd.md | 11 +++++++++
gcc/config/aarch64/aarch64.c | 24 +++++++++++--------
gcc/emit-rtl.c | 1 +
gcc/rtx-vector-builder.c | 6 ++---
gcc/rtx-vector-builder.h | 10 ++++----
gcc/testsuite/gcc.c-torture/compile/pr97141.c | 8 +++++++
gcc/testsuite/gcc.c-torture/compile/pr98726.c | 7 ++++++
.../gcc.target/aarch64/sve/pr97141.c | 10 ++++++++
.../gcc.target/aarch64/sve/pr98726.c | 9 +++++++
9 files changed, 68 insertions(+), 18 deletions(-)
create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr97141.c
create mode 100644 gcc/testsuite/gcc.c-torture/compile/pr98726.c
create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/pr97141.c
create mode 100644 gcc/testsuite/gcc.target/aarch64/sve/pr98726.c
diff --git a/gcc/config/aarch64/aarch64-simd.md b/gcc/config/aarch64/aarch64-simd.md
index d86e8e72f18..4edee99051c 100644
--- a/gcc/config/aarch64/aarch64-simd.md
+++ b/gcc/config/aarch64/aarch64-simd.md
@@ -35,6 +35,17 @@ (define_expand "mov<mode>"
&& aarch64_mem_pair_operand (operands[0], DImode))
|| known_eq (GET_MODE_SIZE (<MODE>mode), 8))))
operands[1] = force_reg (<MODE>mode, operands[1]);
+
+ /* If a constant is too complex to force to memory (e.g. because it
+ contains CONST_POLY_INTs), build it up from individual elements instead.
+ We should only need to do this before RA; aarch64_legitimate_constant_p
+ should ensure that we don't try to rematerialize the constant later. */
+ if (GET_CODE (operands[1]) == CONST_VECTOR
+ && targetm.cannot_force_const_mem (<MODE>mode, operands[1]))
+ {
+ aarch64_expand_vector_init (operands[0], operands[1]);
+ DONE;
+ }
"
)
diff --git a/gcc/config/aarch64/aarch64.c b/gcc/config/aarch64/aarch64.c
index 5eda9e80bd0..77573e96820 100644
--- a/gcc/config/aarch64/aarch64.c
+++ b/gcc/config/aarch64/aarch64.c
@@ -17925,10 +17925,22 @@ aarch64_legitimate_constant_p (machine_mode mode, rtx x)
{
/* Support CSE and rematerialization of common constants. */
if (CONST_INT_P (x)
- || (CONST_DOUBLE_P (x) && GET_MODE_CLASS (mode) == MODE_FLOAT)
- || GET_CODE (x) == CONST_VECTOR)
+ || (CONST_DOUBLE_P (x) && GET_MODE_CLASS (mode) == MODE_FLOAT))
return true;
+ /* Only accept variable-length vector constants if they can be
+ handled directly.
+
+ ??? It would be possible (but complex) to handle rematerialization
+ of other constants via secondary reloads. */
+ if (!GET_MODE_SIZE (mode).is_constant ())
+ return aarch64_simd_valid_immediate (x, NULL);
+
+ /* Otherwise, accept any CONST_VECTOR that, if all else fails, can at
+ least be forced to memory and loaded from there. */
+ if (GET_CODE (x) == CONST_VECTOR)
+ return !targetm.cannot_force_const_mem (mode, x);
+
/* Do not allow vector struct mode constants for Advanced SIMD.
We could support 0 and -1 easily, but they need support in
aarch64-simd.md. */
@@ -17936,14 +17948,6 @@ aarch64_legitimate_constant_p (machine_mode mode, rtx x)
if (vec_flags == (VEC_ADVSIMD | VEC_STRUCT))
return false;
- /* Only accept variable-length vector constants if they can be
- handled directly.
-
- ??? It would be possible to handle rematerialization of other
- constants via secondary reloads. */
- if (vec_flags & VEC_ANY_SVE)
- return aarch64_simd_valid_immediate (x, NULL);
-
if (GET_CODE (x) == HIGH)
x = XEXP (x, 0);
diff --git a/gcc/emit-rtl.c b/gcc/emit-rtl.c
index b23284e5e56..1113c58c49e 100644
--- a/gcc/emit-rtl.c
+++ b/gcc/emit-rtl.c
@@ -5949,6 +5949,7 @@ bool
valid_for_const_vector_p (machine_mode, rtx x)
{
return (CONST_SCALAR_INT_P (x)
+ || CONST_POLY_INT_P (x)
|| CONST_DOUBLE_AS_FLOAT_P (x)
|| CONST_FIXED_P (x));
}
diff --git a/gcc/rtx-vector-builder.c b/gcc/rtx-vector-builder.c
index 58b3e10a14a..cf9b3dd1af9 100644
--- a/gcc/rtx-vector-builder.c
+++ b/gcc/rtx-vector-builder.c
@@ -46,11 +46,11 @@ rtx_vector_builder::build (rtvec v)
rtx
rtx_vector_builder::apply_step (rtx base, unsigned int factor,
- const wide_int &step) const
+ const poly_wide_int &step) const
{
scalar_int_mode int_mode = as_a <scalar_int_mode> (GET_MODE_INNER (m_mode));
- return immed_wide_int_const (wi::add (rtx_mode_t (base, int_mode),
- factor * step),
+ return immed_wide_int_const (wi::to_poly_wide (base, int_mode)
+ + factor * step,
int_mode);
}
diff --git a/gcc/rtx-vector-builder.h b/gcc/rtx-vector-builder.h
index ea32208b30a..30a91e80b40 100644
--- a/gcc/rtx-vector-builder.h
+++ b/gcc/rtx-vector-builder.h
@@ -44,8 +44,8 @@ private:
bool equal_p (rtx, rtx) const;
bool allow_steps_p () const;
bool integral_p (rtx) const;
- wide_int step (rtx, rtx) const;
- rtx apply_step (rtx, unsigned int, const wide_int &) const;
+ poly_wide_int step (rtx, rtx) const;
+ rtx apply_step (rtx, unsigned int, const poly_wide_int &) const;
bool can_elide_p (rtx) const { return true; }
void note_representative (rtx *, rtx) {}
@@ -115,11 +115,11 @@ rtx_vector_builder::integral_p (rtx elt) const
/* Return the value of element ELT2 minus the value of element ELT1.
Both elements are known to be CONST_SCALAR_INT_Ps. */
-inline wide_int
+inline poly_wide_int
rtx_vector_builder::step (rtx elt1, rtx elt2) const
{
- return wi::sub (rtx_mode_t (elt2, GET_MODE_INNER (m_mode)),
- rtx_mode_t (elt1, GET_MODE_INNER (m_mode)));
+ return (wi::to_poly_wide (elt2, GET_MODE_INNER (m_mode))
+ - wi::to_poly_wide (elt1, GET_MODE_INNER (m_mode)));
}
#endif
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr97141.c b/gcc/testsuite/gcc.c-torture/compile/pr97141.c
new file mode 100644
index 00000000000..1a9ff830a22
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr97141.c
@@ -0,0 +1,8 @@
+int a;
+short b, c;
+short d(short e, short f) { return e + f; }
+void g(void) {
+ a = -9;
+ for (; a != 51; a = d(a, 5))
+ b |= c;
+}
diff --git a/gcc/testsuite/gcc.c-torture/compile/pr98726.c b/gcc/testsuite/gcc.c-torture/compile/pr98726.c
new file mode 100644
index 00000000000..ce24b18ce55
--- /dev/null
+++ b/gcc/testsuite/gcc.c-torture/compile/pr98726.c
@@ -0,0 +1,7 @@
+int a, c;
+char b;
+int d() {
+ a = 0;
+ for (; a <= 21; a = (short)a + 1)
+ b &= c;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/pr97141.c b/gcc/testsuite/gcc.target/aarch64/sve/pr97141.c
new file mode 100644
index 00000000000..942e4a48d91
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/pr97141.c
@@ -0,0 +1,10 @@
+/* { dg-options "-O3" } */
+
+int a;
+short b, c;
+short d(short e, short f) { return e + f; }
+void g(void) {
+ a = -9;
+ for (; a != 51; a = d(a, 5))
+ b |= c;
+}
diff --git a/gcc/testsuite/gcc.target/aarch64/sve/pr98726.c b/gcc/testsuite/gcc.target/aarch64/sve/pr98726.c
new file mode 100644
index 00000000000..2395cab57e5
--- /dev/null
+++ b/gcc/testsuite/gcc.target/aarch64/sve/pr98726.c
@@ -0,0 +1,9 @@
+/* { dg-options "-O3" } */
+
+int a, c;
+char b;
+int d() {
+ a = 0;
+ for (; a <= 21; a = (short)a + 1)
+ b &= c;
+}
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