[gcc r15-1048] Adjust rtx_cost for MEM to enable more simplication

[hongtao Liu]

https://gcc.gnu.org/g:961dd0d635217c703a38c48903981e0d60962546

commit r15-1048-g961dd0d635217c703a38c48903981e0d60962546
Author: liuhongt <hongtao.liu@intel.com>
Date:   Fri Apr 19 10:39:53 2024 +0800

    Adjust rtx_cost for MEM to enable more simplication
    
    For CONST_VECTOR_DUPLICATE_P in constant_pool, it is just broadcast or
    variants in ix86_vector_duplicate_simode_const.
    Adjust the cost to COSTS_N_INSNS (2) + speed which should be a little
    bit larger than broadcast.
    
    gcc/ChangeLog:
            PR target/114428
            * config/i386/i386.cc (ix86_rtx_costs): Adjust cost for
            CONST_VECTOR_DUPLICATE_P in constant_pool.
            * config/i386/i386-expand.cc (ix86_broadcast_from_constant):
            Remove static.
            * config/i386/i386-protos.h (ix86_broadcast_from_constant):
            Declare.
    
    gcc/testsuite/ChangeLog:
    
            * gcc.target/i386/pr114428.c: New test.

Diff:
---
 gcc/config/i386/i386-expand.cc           |  2 +-
 gcc/config/i386/i386-protos.h            |  1 +
 gcc/config/i386/i386.cc                  | 13 +++++++++++++
 gcc/testsuite/gcc.target/i386/pr114428.c | 18 ++++++++++++++++++
 4 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc
index 215a998fc26..56d29c15f9a 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -588,7 +588,7 @@ ix86_expand_move (machine_mode mode, rtx operands[])
 
 /* OP is a memref of CONST_VECTOR, return scalar constant mem
    if CONST_VECTOR is a vec_duplicate, else return NULL.  */
-static rtx
+rtx
 ix86_broadcast_from_constant (machine_mode mode, rtx op)
 {
   int nunits = GET_MODE_NUNITS (mode);
diff --git a/gcc/config/i386/i386-protos.h b/gcc/config/i386/i386-protos.h
index dbc861fb1ea..90712769200 100644
--- a/gcc/config/i386/i386-protos.h
+++ b/gcc/config/i386/i386-protos.h
@@ -107,6 +107,7 @@ extern void ix86_expand_clear (rtx);
 extern void ix86_expand_move (machine_mode, rtx[]);
 extern void ix86_expand_vector_move (machine_mode, rtx[]);
 extern void ix86_expand_vector_move_misalign (machine_mode, rtx[]);
+extern rtx ix86_broadcast_from_constant (machine_mode, rtx);
 extern rtx ix86_fixup_binary_operands (enum rtx_code, machine_mode,
 				       rtx[], bool = false);
 extern void ix86_fixup_binary_operands_no_copy (enum rtx_code, machine_mode,
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 271da127a89..a9d62c84c52 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -22191,6 +22191,19 @@ ix86_rtx_costs (rtx x, machine_mode mode, int outer_code_i, int opno,
       return true;
 
     case MEM:
+      /* CONST_VECTOR_DUPLICATE_P in constant_pool is just broadcast.
+	 or variants in ix86_vector_duplicate_simode_const.  */
+
+      if (GET_MODE_SIZE (mode) >= 16
+	  && VECTOR_MODE_P (mode)
+	  && SYMBOL_REF_P (XEXP (x, 0))
+	  && CONSTANT_POOL_ADDRESS_P (XEXP (x, 0))
+	  && ix86_broadcast_from_constant (mode, x))
+	{
+	  *total = COSTS_N_INSNS (2) + speed;
+	  return true;
+	}
+
       /* An insn that accesses memory is slightly more expensive
          than one that does not.  */
       if (speed)
diff --git a/gcc/testsuite/gcc.target/i386/pr114428.c b/gcc/testsuite/gcc.target/i386/pr114428.c
new file mode 100644
index 00000000000..bbbc5a080f6
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr114428.c
@@ -0,0 +1,18 @@
+/* { dg-do compile } */
+/* { dg-options "-march=x86-64-v3 -mno-avx512f -O2" } */
+/* { dg-final { scan-assembler-not "vpsra[dw]" } } */
+
+void
+foo2 (char* __restrict a, short* b)
+{
+  for (int i = 0; i != 32; i++)
+    a[i] = b[i] >> (short)8;
+}
+
+void
+foo3 (char* __restrict a, short* b)
+{
+  for (int i = 0; i != 16; i++)
+    a[i] = b[i] >> (short)8;
+}
+