[gcc r17-1735] x86_cse: Use integer CONST_VECTOR to load FP CONST_VECTOR

[H.J. Lu]

https://gcc.gnu.org/g:d9a8473311915852f3229f4177d13988e3393c1d

commit r17-1735-gd9a8473311915852f3229f4177d13988e3393c1d
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Fri Jun 19 16:31:26 2026 +0800

    x86_cse: Use integer CONST_VECTOR to load FP CONST_VECTOR
    
    Use integer CONST_VECTOR:
    
    (const_vector:V2SI [
            (const_int 1073741824 [0x40000000]) repeated x2
        ])
    
    instead of
    
    (const_vector:V2SF [
            (const_int 1073741824 [0x40000000]) repeated x2
        ])
    
    to load FP CONST_VECTOR converted from const_int:
    
    (insn 25 24 27 2 (set (subreg:SI (reg/v:SF 144 [ d ]) 0)
            (const_int 1073741824 [0x40000000])) "x.c":4:18 100 {*movsi_internal}
         (nil))
    ...
    (insn 90 88 91 2 (set (reg:V2SF 202 [ _15 ])
            (vec_duplicate:V2SF (reg/v:SF 144 [ d ]))) "x.c":4:5 2137 {*vec_dupv2sf}
         (expr_list:REG_DEAD (reg/v:SF 144 [ d ])
            (nil)))
    
    into GPR:
    
    (insn 90 88 91 2 (set (subreg:DI (reg:V2SF 202 [ _15 ]) 0)
            (const_int 4611686019501129728 [0x4000000040000000])) "x.c":4:5 99 {*movdi_internal}
         (expr_list:REG_DEAD (reg/v:SF 144 [ d ])
            (nil)))
    
    gcc/
    
            PR target/125895
            * config/i386/i386-features.cc (pass_x86_cse::x86_cse): Use
            integer CONST_VECTOR to load FP CONST_VECTOR converted from
            const_int.
    
    gcc/testsuite/
    
            PR target/125895
            * gcc.target/i386/pr125895.c: New test.
    
    Signed-off-by: H.J. Lu <hjl.tools@gmail.com>

Diff:
---
 gcc/config/i386/i386-features.cc         | 11 +++++++++++
 gcc/testsuite/gcc.target/i386/pr125895.c | 10 ++++++++++
 2 files changed, 21 insertions(+)

diff --git a/gcc/config/i386/i386-features.cc b/gcc/config/i386/i386-features.cc
index aa16c7dc56c4..10d84f520016 100644
--- a/gcc/config/i386/i386-features.cc
+++ b/gcc/config/i386/i386-features.cc
@@ -5053,6 +5053,17 @@ pass_x86_cse::x86_cse (void)
 		    rtvec v = rtvec_alloc (nunits);
 		    for (int j = 0; j < nunits ; j++)
 		      RTVEC_ELT (v, j) = load->val;
+		    if (CONST_INT_P (load->val)
+			&& GET_MODE_CLASS (mode) != MODE_VECTOR_INT)
+		      {
+			gcc_assert (load->size <= UNITS_PER_WORD);
+			machine_mode imode = GET_MODE_INNER (mode);
+			class scalar_mode i_mode
+			  = int_mode_for_mode (imode).require ();
+			mode = mode_for_vector (i_mode,
+						nunits).require ();
+		      }
+
 		    broadcast_source = gen_rtx_CONST_VECTOR (mode, v);
 		  }
 
diff --git a/gcc/testsuite/gcc.target/i386/pr125895.c b/gcc/testsuite/gcc.target/i386/pr125895.c
new file mode 100644
index 000000000000..adc42955e240
--- /dev/null
+++ b/gcc/testsuite/gcc.target/i386/pr125895.c
@@ -0,0 +1,10 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=x86-64" } */
+
+__attribute__((__vector_size__(2 * sizeof(float)))) float b;
+void a(float d) {
+  double c;
+  b -= *(float *)__builtin_memcpy(&d, &c, 1);
+  __asm__("");
+  a(2);
+}