RISC-V: Increase cost for vec_construct [PR118019].

For a generic vec_construct from scalar elements we need to load each
scalar element and move it over to a vector register.
Right now we only use a cost of 1 per element.

This patch uses register-move cost as well as scalar_to_vec and
multiplies it with the number of elements in the vector instead.

	PR target/118019

gcc/ChangeLog:

	* config/riscv/riscv.cc (riscv_builtin_vectorization_cost):
	Increase vec_construct cost.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/rvv/autovec/pr118019.c: New test.

diff --git a/gcc/config/riscv/riscv.cc b/gcc/config/riscv/riscv.cc
index be2ebf9d9c09a7892b9f2d375fb15673304cc752..aa8a4562d9af6fda3b35c0a4eb0a5795c94d2fd2 100644 (file)
--- a/gcc/config/riscv/riscv.cc
+++ b/gcc/config/riscv/riscv.cc
@@ -12263,7 +12263,13 @@ riscv_builtin_vectorization_cost (enum vect_cost_for_stmt type_of_cost,
       return fp ? common_costs->fp_stmt_cost : common_costs->int_stmt_cost;
 
     case vec_construct:
-      return estimated_poly_value (TYPE_VECTOR_SUBPARTS (vectype));
+       {
+         /* TODO: This is too pessimistic in case we can splat.  */
+         int regmove_cost = fp ? costs->regmove->FR2VR
+           : costs->regmove->GR2VR;
+         return (regmove_cost + common_costs->scalar_to_vec_cost)
+           * estimated_poly_value (TYPE_VECTOR_SUBPARTS (vectype));
+       }
 
     default:
       gcc_unreachable ();

diff --git a/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118019.c b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118019.c
new file mode 100644 (file)
index 0000000..02b3ab4
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/rvv/autovec/pr118019.c
@@ -0,0 +1,52 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -march=rv64gcv_zvl512b -mabi=lp64d -mstrict-align -mvector-strict-align" } */
+
+/* Make sure we do not construct the vector element-wise despite
+   slow misaligned scalar and vector accesses.  */
+
+typedef unsigned char uint8_t;
+typedef unsigned short uint16_t;
+typedef unsigned int uint32_t;
+
+#define HADAMARD4(d0, d1, d2, d3, s0, s1, s2, s3)                              \
+  {                                                                            \
+    int t0 = s0 + s1;                                                          \
+    int t1 = s0 - s1;                                                          \
+    int t2 = s2 + s3;                                                          \
+    int t3 = s2 - s3;                                                          \
+    d0 = t0 + t2;                                                              \
+    d2 = t0 - t2;                                                              \
+    d1 = t1 + t3;                                                              \
+    d3 = t1 - t3;                                                              \
+  }
+
+uint32_t
+abs2 (uint32_t a)
+{
+  uint32_t s = ((a >> 15) & 0x10001) * 0xffff;
+  return (a + s) ^ s;
+}
+
+int
+x264_pixel_satd_8x4 (uint8_t *pix1, int i_pix1, uint8_t *pix2, int i_pix2)
+{
+  uint32_t tmp[4][4];
+  uint32_t a0, a1, a2, a3;
+  int sum = 0;
+  for (int i = 0; i < 4; i++, pix1 += i_pix1, pix2 += i_pix2)
+    {
+      a0 = (pix1[0] - pix2[0]) + ((pix1[4] - pix2[4]) << 16);
+      a1 = (pix1[1] - pix2[1]) + ((pix1[5] - pix2[5]) << 16);
+      a2 = (pix1[2] - pix2[2]) + ((pix1[6] - pix2[6]) << 16);
+      a3 = (pix1[3] - pix2[3]) + ((pix1[7] - pix2[7]) << 16);
+      HADAMARD4 (tmp[i][0], tmp[i][1], tmp[i][2], tmp[i][3], a0, a1, a2, a3);
+    }
+  for (int i = 0; i < 4; i++)
+    {
+      HADAMARD4 (a0, a1, a2, a3, tmp[0][i], tmp[1][i], tmp[2][i], tmp[3][i]);
+      sum += abs2 (a0) + abs2 (a1) + abs2 (a2) + abs2 (a3);
+    }
+  return (((uint16_t) sum) + ((uint32_t) sum >> 16)) >> 1;
+}
+
+/* { dg-final { scan-assembler-not "lbu" } } */