[Bug rtl-optimization/104664] [12 Regression] ICE: in extract_constrain_insn, at recog.cc:2670 (insn does not satisfy its constraints) with -Og -ffinite-math-only

[wwwhhhyyy333 at gmail dot com via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104664

--- Comment #4 from Hongyu Wang <wwwhhhyyy333 at gmail dot com> ---
(In reply to Uroš Bizjak from comment #3)

> Reconfirmed as RA issue.

I'm afraid we'd avoid pattern like

(insn 180 179 182 2 (set (reg:V8HF 220)                                        
        (subreg:V8HF (reg:HF 221) 0)) "pr104664.c":12:7 1710 {movv8hf_internal}

since we don't have corresponding pattern with subreg. Reload might not aware
of the newly inserted regs properly, as the message shows

Set class ALL_REGS for r221
Set class ALL_REGS for r220

I'm testing

diff --git a/gcc/config/i386/i386-expand.cc b/gcc/config/i386/i386-expand.cc    
index 6cf1a0b9cb6..658516d86a2 100644
--- a/gcc/config/i386/i386-expand.cc
+++ b/gcc/config/i386/i386-expand.cc
@@ -14883,7 +14883,12 @@ ix86_expand_vector_init_duplicate (bool mmx_ok,
machine_mode mode,
          dperm.one_operand_p = true;

          if (mode == V8HFmode)
-           tmp1 = lowpart_subreg (V8HFmode, force_reg (HFmode, val), HFmode);  
+           {
+             tmp1 = force_reg (HFmode, val);
+             tmp2 = gen_reg_rtx (mode);
+             emit_insn (gen_vec_setv8hf_0 (tmp2, CONST0_RTX (mode), tmp1));    
+             tmp1 = gen_lowpart (mode, tmp2);
+           }