cranelift: add i64.{ishl,ushr,ashr} libcalls.

These libcalls are useful for 32-bit platforms.

On x86_32 in particular, commit 4ec16fa0 added support for legalizing
64-bit shifts through SIMD operations. However, that legalization
requires SIMD to be enabled and SSE 4.1 to be supported, which is not
acceptable as a hard requirement.

cranelift/codegen/src/ir/libcall.rs

@@ -32,6 +32,12 @@ pub enum LibCall {
     UremI64,
     /// srem.i64
     SremI64,
+    /// ishl.i64
+    IshlI64,
+    /// ushr.i64
+    UshrI64,
+    /// sshr.i64
+    SshrI64,
     /// ceil.f32
     CeilF32,
     /// ceil.f64
@@ -75,6 +81,9 @@ impl FromStr for LibCall {
             "SdivI64" => Ok(Self::SdivI64),
             "UremI64" => Ok(Self::UremI64),
             "SremI64" => Ok(Self::SremI64),
+            "IshlI64" => Ok(Self::IshlI64),
+            "UshrI64" => Ok(Self::UshrI64),
+            "SshrI64" => Ok(Self::SshrI64),
             "CeilF32" => Ok(Self::CeilF32),
             "CeilF64" => Ok(Self::CeilF64),
             "FloorF32" => Ok(Self::FloorF32),
@@ -105,6 +114,9 @@ impl LibCall {
                 Opcode::Sdiv => Self::SdivI64,
                 Opcode::Urem => Self::UremI64,
                 Opcode::Srem => Self::SremI64,
+                Opcode::Ishl => Self::IshlI64,
+                Opcode::Ushr => Self::UshrI64,
+                Opcode::Sshr => Self::SshrI64,
                 _ => return None,
             },
             types::F32 => match opcode {

cranelift/codegen/src/isa/x86/enc_tables.rs

@@ -13,6 +13,7 @@ use crate::isa::encoding::base_size;
 use crate::isa::encoding::{Encoding, RecipeSizing};
 use crate::isa::RegUnit;
 use crate::isa::{self, TargetIsa};
+use crate::legalizer::expand_as_libcall;
 use crate::predicates;
 use crate::regalloc::RegDiversions;
 
@@ -1428,10 +1429,20 @@ fn convert_ushr(
             pos.func.dfg.replace(inst).x86_psrl(arg0, shift_index);
         } else if arg0_type == I64 {
             // 64 bit shifts need to be legalized on x86_32.
-            let value = expand_dword_to_xmm(&mut pos, arg0, arg0_type);
-            let amount = expand_dword_to_xmm(&mut pos, arg1, arg1_type);
-            let shifted = pos.ins().x86_psrl(value, amount);
-            contract_dword_from_xmm(&mut pos, inst, shifted, arg0_type);
+            let x86_isa = isa
+                .as_any()
+                .downcast_ref::<isa::x86::Isa>()
+                .expect("the target ISA must be x86 at this point");
+            if x86_isa.isa_flags.has_sse41() {
+                // if we have pinstrq/pextrq (SSE 4.1), legalize to that
+                let value = expand_dword_to_xmm(&mut pos, arg0, arg0_type);
+                let amount = expand_dword_to_xmm(&mut pos, arg1, arg1_type);
+                let shifted = pos.ins().x86_psrl(value, amount);
+                contract_dword_from_xmm(&mut pos, inst, shifted, arg0_type);
+            } else {
+                // otherwise legalize to libcall
+                expand_as_libcall(inst, func, isa);
+            }
         } else {
             // Everything else should be already legal.
             unreachable!()
@@ -1502,10 +1513,20 @@ fn convert_ishl(
             pos.func.dfg.replace(inst).x86_psll(arg0, shift_index);
         } else if arg0_type == I64 {
             // 64 bit shifts need to be legalized on x86_32.
-            let value = expand_dword_to_xmm(&mut pos, arg0, arg0_type);
-            let amount = expand_dword_to_xmm(&mut pos, arg1, arg1_type);
-            let shifted = pos.ins().x86_psll(value, amount);
-            contract_dword_from_xmm(&mut pos, inst, shifted, arg0_type);
+            let x86_isa = isa
+                .as_any()
+                .downcast_ref::<isa::x86::Isa>()
+                .expect("the target ISA must be x86 at this point");
+            if x86_isa.isa_flags.has_sse41() {
+                // if we have pinstrq/pextrq (SSE 4.1), legalize to that
+                let value = expand_dword_to_xmm(&mut pos, arg0, arg0_type);
+                let amount = expand_dword_to_xmm(&mut pos, arg1, arg1_type);
+                let shifted = pos.ins().x86_psll(value, amount);
+                contract_dword_from_xmm(&mut pos, inst, shifted, arg0_type);
+            } else {
+                // otherwise legalize to libcall
+                expand_as_libcall(inst, func, isa);
+            }
         } else {
             // Everything else should be already legal.
             unreachable!()

cranelift/codegen/src/legalizer/mod.rs

@@ -35,7 +35,7 @@ mod table;
 use self::call::expand_call;
 use self::globalvalue::expand_global_value;
 use self::heap::expand_heap_addr;
-use self::libcall::expand_as_libcall;
+pub(crate) use self::libcall::expand_as_libcall;
 use self::table::expand_table_addr;
 
 enum LegalizeInstResult {