When generating a SUBREG from V16QI to V2HF, validate_subreg fails since
the V2HF size (4 bytes) is smaller than its natural size (word size).
Update remove_redundant_vector_load to skip if the mode size is smaller
than its natural size.
gcc/
PR target/120036
* config/i386/i386-features.cc (remove_redundant_vector_load):
Also skip if the mode size is smaller than its natural size.
gcc/testsuite/
PR target/120036
* g++.target/i386/pr120036.C: New test.
--
H.J.
From 6bfacf6014965d3ec498620dd9951efca9ad6015 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.to...@gmail.com>
Date: Thu, 1 May 2025 06:30:41 +0800
Subject: [PATCH] x86: Skip if the mode size is smaller than its natural size
When generating a SUBREG from V16QI to V2HF, validate_subreg fails since
the V2HF size (4 bytes) is smaller than its natural size (word size).
Update remove_redundant_vector_load to skip if the mode size is smaller
than its natural size.
gcc/
PR target/120036
* config/i386/i386-features.cc (remove_redundant_vector_load):
Also skip if the mode size is smaller than its natural size.
gcc/testsuite/
PR target/120036
* g++.target/i386/pr120036.C: New test.
Signed-off-by: H.J. Lu <hjl.to...@gmail.com>
---
gcc/config/i386/i386-features.cc | 7 +-
gcc/testsuite/g++.target/i386/pr120036.C | 113 +++++++++++++++++++++++
2 files changed, 118 insertions(+), 2 deletions(-)
create mode 100644 gcc/testsuite/g++.target/i386/pr120036.C
diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index 31f3ee2ef17..8e12ca88f7a 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -3395,8 +3395,11 @@ remove_redundant_vector_load (void)
rtx dest = SET_DEST (set);
machine_mode mode = GET_MODE (dest);
- /* Skip non-vector instruction. */
- if (!VECTOR_MODE_P (mode))
+ /* Skip non-vector instruction. Also skip if the mode size is
+ smaller than its natural size to avoid validate_subreg
+ failure. */
+ if (!VECTOR_MODE_P (mode)
+ || GET_MODE_SIZE (mode) < ix86_regmode_natural_size (mode))
continue;
rtx src = SET_SRC (set);
diff --git a/gcc/testsuite/g++.target/i386/pr120036.C b/gcc/testsuite/g++.target/i386/pr120036.C
new file mode 100644
index 00000000000..a2fc24f1286
--- /dev/null
+++ b/gcc/testsuite/g++.target/i386/pr120036.C
@@ -0,0 +1,113 @@
+/* { dg-do compile { target fpic } } */
+/* { dg-options "-O2 -std=c++11 -march=sapphirerapids -fPIC" } */
+
+typedef _Float16 Native;
+struct float16_t
+{
+ Native native;
+ float16_t ();
+ float16_t (Native arg) : native (arg) {}
+ operator Native ();
+ float16_t
+ operator+ (float16_t rhs)
+ {
+ return native + rhs.native;
+ }
+ float16_t
+ operator* (float16_t)
+ {
+ return native * native;
+ }
+};
+template <int N> struct Simd
+{
+ static constexpr int kPrivateLanes = N;
+};
+template <int N> struct ClampNAndPow2
+{
+ using type = Simd<N>;
+};
+template <int kLimit> struct CappedTagChecker
+{
+ static constexpr int N = sizeof (int) ? kLimit : 0;
+ using type = typename ClampNAndPow2<N>::type;
+};
+template <typename, int kLimit, int>
+using CappedTag = typename CappedTagChecker<kLimit>::type;
+template <class D>
+int
+Lanes (D)
+{
+ return D::kPrivateLanes;
+}
+template <class D> int Zero (D);
+template <class D> using VFromD = decltype (Zero (D ()));
+struct Vec512
+{
+ __attribute__ ((__vector_size__ (16))) _Float16 raw;
+};
+Vec512 Zero (Simd<2>);
+template <class D> void ReduceSum (D, VFromD<D>);
+struct Dot
+{
+ template <int, class D, typename T>
+ static T
+ Compute (D d, T *pa, int num_elements)
+ {
+ T *pb;
+ int N = Lanes (d), i = 0;
+ if (__builtin_expect (num_elements < N, 0))
+ {
+ T sum0 = 0, sum1 = 0;
+ for (; i + 2 <= num_elements; i += 2)
+ {
+ float16_t __trans_tmp_6 = pa[i] * pb[i],
+ __trans_tmp_5 = sum0 + __trans_tmp_6,
+ __trans_tmp_8 = pa[i + 1] * pb[1],
+ __trans_tmp_7 = sum1 + __trans_tmp_8;
+ sum0 = __trans_tmp_5;
+ sum1 = __trans_tmp_7;
+ }
+ float16_t __trans_tmp_9 = sum0 + sum1;
+ return __trans_tmp_9;
+ }
+ decltype (Zero (d)) sum0;
+ ReduceSum (d, sum0);
+ __builtin_trap ();
+ }
+};
+template <int kMul, class Test, int kPow2> struct ForeachCappedR
+{
+ static void
+ Do (int min_lanes, int max_lanes)
+ {
+ CappedTag<int, kMul, kPow2> d;
+ Test () (int (), d);
+ ForeachCappedR<kMul / 2, Test, kPow2>::Do (min_lanes, max_lanes);
+ }
+};
+template <class Test, int kPow2> struct ForeachCappedR<0, Test, kPow2>
+{
+ static void Do (int, int);
+};
+struct TestDot
+{
+ template <class T, class D>
+ void
+ operator() (T, D d)
+ {
+ int counts[]{ 1, 3 };
+ for (int num : counts)
+ {
+ float16_t a;
+ T __trans_tmp_4 = Dot::Compute<0> (d, &a, num);
+ }
+ }
+};
+int DotTest_TestAllDot_TestTestBody_max_lanes;
+void
+DotTest_TestAllDot_TestTestBody ()
+{
+ ForeachCappedR<64, TestDot, 0>::Do (
+ 1, DotTest_TestAllDot_TestTestBody_max_lanes);
+}
--
2.49.0
