X64: Port fpromote to ISLE (#4230)

cranelift/codegen/src/isa/x64/inst.isle

@@ -2817,6 +2817,13 @@
             (_ Unit (emit (MInst.XmmUnaryRmR (SseOpcode.Sqrtpd) x dst))))
         dst))
 
+;; Helper for creating `cvtss2sd` instructions.
+(decl x64_cvtss2sd (Xmm) Xmm)
+(rule (x64_cvtss2sd x)
+      (let ((dst WritableXmm (temp_writable_xmm))
+            (_ Unit (emit (MInst.XmmUnaryRmR (SseOpcode.Cvtss2sd) x dst))))
+        dst))
+
 ;; Helpers for creating `pcmpeq*` instructions.
 (decl x64_pcmpeq (Type Xmm XmmMem) Xmm)
 (rule (x64_pcmpeq $I8X16 x y) (x64_pcmpeqb x y))

cranelift/codegen/src/isa/x64/lower.isle

@@ -2318,6 +2318,10 @@
 (rule (lower (has_type $F64X2 (sqrt x)))
       (x64_sqrtpd x))
 
+;; Rules for `fpromote` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+(rule (lower (has_type $F64 (fpromote x)))
+      (x64_cvtss2sd x))
+
 ;; Rules for `fmin` ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 
 (rule (lower (has_type $F32 (fmin x y)))

cranelift/codegen/src/isa/x64/lower.rs

@@ -1041,11 +1041,7 @@ fn lower_insn_to_regs<C: LowerCtx<I = Inst>>(
         }
 
         Opcode::Fpromote => {
-            // We can't guarantee the RHS (if a load) is 128-bit aligned, so we
-            // must avoid merging a load here.
-            let src = RegMem::reg(put_input_in_reg(ctx, inputs[0]));
-            let dst = get_output_reg(ctx, outputs[0]).only_reg().unwrap();
-            ctx.emit(Inst::xmm_unary_rm_r(SseOpcode::Cvtss2sd, src, dst));
+            implemented_in_isle(ctx);
         }
 
         Opcode::FvpromoteLow => {