cranelift: Implement scalar FMA on x86 (#4460)

x86 does not have dedicated instructions for scalar FMA, lower
to a libcall which seems to be what llvm does.

cranelift/codegen/src/isa/aarch64/lower/isle.rs

@@ -30,6 +30,7 @@ use regalloc2::PReg;
 use std::boxed::Box;
 use std::convert::TryFrom;
 use std::vec::Vec;
+use target_lexicon::Triple;
 
 type BoxCallInfo = Box<CallInfo>;
 type BoxCallIndInfo = Box<CallIndInfo>;
@@ -40,6 +41,7 @@ type BoxExternalName = Box<ExternalName>;
 /// The main entry point for lowering with ISLE.
 pub(crate) fn lower<C>(
     lower_ctx: &mut C,
+    triple: &Triple,
     flags: &Flags,
     isa_flags: &IsaFlags,
     outputs: &[InsnOutput],
@@ -48,9 +50,15 @@ pub(crate) fn lower<C>(
 where
     C: LowerCtx<I = MInst>,
 {
-    lower_common(lower_ctx, flags, isa_flags, outputs, inst, |cx, insn| {
-        generated_code::constructor_lower(cx, insn)
-    })
+    lower_common(
+        lower_ctx,
+        triple,
+        flags,
+        isa_flags,
+        outputs,
+        inst,
+        |cx, insn| generated_code::constructor_lower(cx, insn),
+    )
 }
 
 pub struct ExtendedValue {