Adjust costing of emulated vectorized gather/scatter

Emulated gather/scatter behave similar to strided elementwise
accesses in that they need to decompose the offset vector
and construct or decompose the data vector so handle them
the same way, pessimizing the cases with may elements.

For pr88531-2c.c instead of

.L4:
        leaq    (%r15,%rcx), %rdx
        incl    %edi
        movl    16(%rdx), %r13d
        movl    24(%rdx), %r14d
        movl    (%rdx), %r10d
        movl    4(%rdx), %r9d
        movl    8(%rdx), %ebx
        movl    12(%rdx), %r11d
        movl    20(%rdx), %r12d
        vmovss  (%rax,%r14,4), %xmm2
        movl    28(%rdx), %edx
        vmovss  (%rax,%r13,4), %xmm1
        vmovss  (%rax,%r10,4), %xmm0
        vinsertps       $0x10, (%rax,%rdx,4), %xmm2, %xmm2
        vinsertps       $0x10, (%rax,%r12,4), %xmm1, %xmm1
        vinsertps       $0x10, (%rax,%r9,4), %xmm0, %xmm0
        vmovlhps        %xmm2, %xmm1, %xmm1
        vmovss  (%rax,%rbx,4), %xmm2
        vinsertps       $0x10, (%rax,%r11,4), %xmm2, %xmm2
        vmovlhps        %xmm2, %xmm0, %xmm0
        vinsertf128     $0x1, %xmm1, %ymm0, %ymm0
        vmulps  %ymm3, %ymm0, %ymm0
        vmovups %ymm0, (%r8,%rcx)
        addq    $32, %rcx
        cmpl    %esi, %edi
        jb      .L4

we now prefer

.L4:
        leaq    0(%rbp,%rdx,8), %rcx
        movl    (%rcx), %r10d
        movl    4(%rcx), %ecx
        vmovss  (%rsi,%r10,4), %xmm0
        vinsertps       $0x10, (%rsi,%rcx,4), %xmm0, %xmm0
        vmulps  %xmm1, %xmm0, %xmm0
        vmovlps %xmm0, (%rbx,%rdx,8)
        incq    %rdx
        cmpl    %edi, %edx
        jb      .L4

	* config/i386/i386.cc (ix86_vector_costs::add_stmt_cost):
	Tame down element extracts and scalar loads for gather/scatter
	similar to elementwise strided accesses.

	* gcc.target/i386/pr89618-2.c: New testcase.
	* gcc.target/i386/pr88531-2b.c: Adjust.
	* gcc.target/i386/pr88531-2c.c: Likewise.

diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index cf1cfb722a971737ad821ce5b51034fb3a66a153..b1d08ecdb3d447296499a7fb72635e479a07ffb4 100644 (file)
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -23576,8 +23576,10 @@ ix86_vector_costs::add_stmt_cost (int count, vect_cost_for_stmt kind,
       && stmt_info
       && (STMT_VINFO_TYPE (stmt_info) == load_vec_info_type
          || STMT_VINFO_TYPE (stmt_info) == store_vec_info_type)
-      && STMT_VINFO_MEMORY_ACCESS_TYPE (stmt_info) == VMAT_ELEMENTWISE
-      && TREE_CODE (DR_STEP (STMT_VINFO_DATA_REF (stmt_info))) != INTEGER_CST)
+      && ((STMT_VINFO_MEMORY_ACCESS_TYPE (stmt_info) == VMAT_ELEMENTWISE
+          && (TREE_CODE (DR_STEP (STMT_VINFO_DATA_REF (stmt_info)))
+              != INTEGER_CST))
+         || STMT_VINFO_MEMORY_ACCESS_TYPE (stmt_info) == VMAT_GATHER_SCATTER))
     {
       stmt_cost = ix86_builtin_vectorization_cost (kind, vectype, misalign);
       stmt_cost *= (TYPE_VECTOR_SUBPARTS (vectype) + 1);

diff --git a/gcc/testsuite/gcc.target/i386/pr88531-2b.c b/gcc/testsuite/gcc.target/i386/pr88531-2b.c
index 011607c3d5492832cde2f6eeb49f000345b99763..cdefff2ce8e55ecc3898367cb7ed8f6227e4af50 100644 (file)
--- a/gcc/testsuite/gcc.target/i386/pr88531-2b.c
+++ b/gcc/testsuite/gcc.target/i386/pr88531-2b.c
@@ -3,4 +3,4 @@
 
 #include "pr88531-2a.c"
 
-/* { dg-final { scan-assembler-times "vmulps" 2 } } */
+/* { dg-final { scan-assembler-times "vmulps" 1 } } */

diff --git a/gcc/testsuite/gcc.target/i386/pr88531-2c.c b/gcc/testsuite/gcc.target/i386/pr88531-2c.c
index 0f7ec3832f8e22d6ca9bd755482383e4ed320f54..17b24c0daccd8dca8a3fc3188f565c9b55c27d2b 100644 (file)
--- a/gcc/testsuite/gcc.target/i386/pr88531-2c.c
+++ b/gcc/testsuite/gcc.target/i386/pr88531-2c.c
@@ -3,4 +3,4 @@
 
 #include "pr88531-2a.c"
 
-/* { dg-final { scan-assembler-times "vmulps" 2 } } */
+/* { dg-final { scan-assembler-times "vmulps" 1 } } */

diff --git a/gcc/testsuite/gcc.target/i386/pr89618-2.c b/gcc/testsuite/gcc.target/i386/pr89618-2.c
new file mode 100644 (file)
index 0000000..0b7dcfd
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr89618-2.c
@@ -0,0 +1,23 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -mavx2 -fdump-tree-vect-details" } */
+
+void foo (int n, int *off, double *a)
+{
+  const int m = 32;
+
+  for (int j = 0; j < n/m; ++j)
+    {
+      int const start = j*m;
+      int const end = (j+1)*m;
+
+#pragma GCC ivdep
+      for (int i = start; i < end; ++i)
+       {
+         a[off[i]] = a[i] < 0 ? a[i] : 0;
+       }
+    }
+}
+
+/* Make sure the cost model selects SSE vectors rather than AVX to avoid
+   too many scalar ops for the address computes in the loop.  */
+/* { dg-final { scan-tree-dump "loop vectorized using 16 byte vectors" "vect" } } */