Aarch64: fix narrow integer-register extension with Baldrdash ABI.

In the Baldrdash (SpiderMonkey) embedding, we must take care to
zero-extend all function arguments to callees in integer registers when
the types are narrower than 64 bits. This is because, unlike the native
SysV ABI, the Baldrdash ABI expects high bits to be cleared. Not doing
so leads to difficult-to-trace errors where high bits falsely tag an
int32 as e.g. an object pointer, leading to potential security issues.

cranelift/codegen/src/isa/aarch64/abi.rs

@@ -113,9 +113,9 @@ use log::{debug, trace};
 #[derive(Clone, Copy, Debug)]
 enum ABIArg {
     /// In a real register.
-    Reg(RealReg, ir::Type),
+    Reg(RealReg, ir::Type, ir::ArgumentExtension),
     /// Arguments only: on stack, at given offset from SP at entry.
-    Stack(i64, ir::Type),
+    Stack(i64, ir::Type, ir::ArgumentExtension),
 }
 
 /// AArch64 ABI information shared between body (callee) and caller.
@@ -187,6 +187,7 @@ fn try_fill_baldrdash_reg(call_conv: isa::CallConv, param: &ir::AbiParam) -> Opt
                 Some(ABIArg::Reg(
                     xreg(BALDRDASH_TLS_REG).to_real_reg(),
                     ir::types::I64,
+                    param.extension,
                 ))
             }
             &ir::ArgumentPurpose::SignatureId => {
@@ -194,6 +195,7 @@ fn try_fill_baldrdash_reg(call_conv: isa::CallConv, param: &ir::AbiParam) -> Opt
                 Some(ABIArg::Reg(
                     xreg(BALDRDASH_SIG_REG).to_real_reg(),
                     ir::types::I64,
+                    param.extension,
                 ))
             }
             _ => None,
@@ -279,7 +281,11 @@ fn compute_arg_locs(
             } else {
                 vreg(*next_reg)
             };
-            ret.push(ABIArg::Reg(reg.to_real_reg(), param.value_type));
+            ret.push(ABIArg::Reg(
+                reg.to_real_reg(),
+                param.value_type,
+                param.extension,
+            ));
             *next_reg += 1;
         } else {
             // Compute size. Every arg takes a minimum slot of 8 bytes. (16-byte
@@ -289,7 +295,11 @@ fn compute_arg_locs(
             // Align.
             debug_assert!(size.is_power_of_two());
             next_stack = (next_stack + size - 1) & !(size - 1);
-            ret.push(ABIArg::Stack(next_stack as i64, param.value_type));
+            ret.push(ABIArg::Stack(
+                next_stack as i64,
+                param.value_type,
+                param.extension,
+            ));
             next_stack += size;
         }
     }
@@ -301,9 +311,17 @@ fn compute_arg_locs(
     let extra_arg = if add_ret_area_ptr {
         debug_assert!(args_or_rets == ArgsOrRets::Args);
         if next_xreg < max_reg_vals {
-            ret.push(ABIArg::Reg(xreg(next_xreg).to_real_reg(), I64));
+            ret.push(ABIArg::Reg(
+                xreg(next_xreg).to_real_reg(),
+                I64,
+                ir::ArgumentExtension::None,
+            ));
         } else {
-            ret.push(ABIArg::Stack(next_stack as i64, I64));
+            ret.push(ABIArg::Stack(
+                next_stack as i64,
+                I64,
+                ir::ArgumentExtension::None,
+            ));
             next_stack += 8;
         }
         Some(ret.len() - 1)
@@ -491,7 +509,7 @@ fn get_special_purpose_param_register(
 ) -> Option<Reg> {
     let idx = f.signature.special_param_index(purpose)?;
     match abi.args[idx] {
-        ABIArg::Reg(reg, _) => Some(reg.to_reg()),
+        ABIArg::Reg(reg, ..) => Some(reg.to_reg()),
         ABIArg::Stack(..) => None,
     }
 }
@@ -866,7 +884,7 @@ impl ABIBody for AArch64ABIBody {
     fn liveins(&self) -> Set<RealReg> {
         let mut set: Set<RealReg> = Set::empty();
         for &arg in &self.sig.args {
-            if let ABIArg::Reg(r, _) = arg {
+            if let ABIArg::Reg(r, ..) = arg {
                 set.insert(r);
             }
         }
@@ -876,7 +894,7 @@ impl ABIBody for AArch64ABIBody {
     fn liveouts(&self) -> Set<RealReg> {
         let mut set: Set<RealReg> = Set::empty();
         for &ret in &self.sig.rets {
-            if let ABIArg::Reg(r, _) = ret {
+            if let ABIArg::Reg(r, ..) = ret {
                 set.insert(r);
             }
         }
@@ -897,8 +915,10 @@ impl ABIBody for AArch64ABIBody {
 
     fn gen_copy_arg_to_reg(&self, idx: usize, into_reg: Writable<Reg>) -> Inst {
         match &self.sig.args[idx] {
-            &ABIArg::Reg(r, ty) => Inst::gen_move(into_reg, r.to_reg(), ty),
+            // Extension mode doesn't matter (we're copying out, not in; we
-            &ABIArg::Stack(off, ty) => load_stack(
+            // ignore high bits by convention).
+            &ABIArg::Reg(r, ty, _) => Inst::gen_move(into_reg, r.to_reg(), ty),
+            &ABIArg::Stack(off, ty, _) => load_stack(
                 MemArg::FPOffset(self.fp_to_arg_offset() + off, ty),
                 into_reg,
                 ty,
@@ -921,15 +941,10 @@ impl ABIBody for AArch64ABIBody {
         }
     }
 
-    fn gen_copy_reg_to_retval(
+    fn gen_copy_reg_to_retval(&self, idx: usize, from_reg: Writable<Reg>) -> Vec<Inst> {
-        &self,
-        idx: usize,
-        from_reg: Writable<Reg>,
-        ext: ArgumentExtension,
-    ) -> Vec<Inst> {
         let mut ret = Vec::new();
         match &self.sig.rets[idx] {
-            &ABIArg::Reg(r, ty) => {
+            &ABIArg::Reg(r, ty, ext) => {
                 let from_bits = ty_bits(ty) as u8;
                 let dest_reg = Writable::from_reg(r.to_reg());
                 match (ext, from_bits) {
@@ -954,7 +969,7 @@ impl ABIBody for AArch64ABIBody {
                     _ => ret.push(Inst::gen_move(dest_reg, from_reg.to_reg(), ty)),
                 };
             }
-            &ABIArg::Stack(off, ty) => {
+            &ABIArg::Stack(off, ty, ext) => {
                 let from_bits = ty_bits(ty) as u8;
                 // Trash the from_reg; it should be its last use.
                 match (ext, from_bits) {
@@ -1364,7 +1379,7 @@ fn abisig_to_uses_and_defs(sig: &ABISig) -> (Vec<Reg>, Vec<Writable<Reg>>) {
     let mut uses = Vec::new();
     for arg in &sig.args {
         match arg {
-            &ABIArg::Reg(reg, _) => uses.push(reg.to_reg()),
+            &ABIArg::Reg(reg, ..) => uses.push(reg.to_reg()),
             _ => {}
         }
     }
@@ -1373,7 +1388,7 @@ fn abisig_to_uses_and_defs(sig: &ABISig) -> (Vec<Reg>, Vec<Writable<Reg>>) {
     let mut defs = get_caller_saves(sig.call_conv);
     for ret in &sig.rets {
         match ret {
-            &ABIArg::Reg(reg, _) => defs.push(Writable::from_reg(reg.to_reg())),
+            &ABIArg::Reg(reg, ..) => defs.push(Writable::from_reg(reg.to_reg())),
             _ => {}
         }
     }
@@ -1469,12 +1484,49 @@ impl ABICall for AArch64ABICall {
         from_reg: Reg,
     ) {
         match &self.sig.args[idx] {
-            &ABIArg::Reg(reg, ty) => ctx.emit(Inst::gen_move(
+            &ABIArg::Reg(reg, ty, ext)
-                Writable::from_reg(reg.to_reg()),
+                if ext != ir::ArgumentExtension::None && ty_bits(ty) < 64 =>
-                from_reg,
+            {
-                ty,
+                assert_eq!(RegClass::I64, reg.get_class());
-            )),
+                let signed = match ext {
-            &ABIArg::Stack(off, ty) => {
+                    ir::ArgumentExtension::Uext => false,
+                    ir::ArgumentExtension::Sext => true,
+                    _ => unreachable!(),
+                };
+                ctx.emit(Inst::Extend {
+                    rd: Writable::from_reg(reg.to_reg()),
+                    rn: from_reg,
+                    signed,
+                    from_bits: ty_bits(ty) as u8,
+                    to_bits: 64,
+                });
+            }
+            &ABIArg::Reg(reg, ty, _) => {
+                ctx.emit(Inst::gen_move(
+                    Writable::from_reg(reg.to_reg()),
+                    from_reg,
+                    ty,
+                ));
+            }
+            &ABIArg::Stack(off, ty, ext) => {
+                if ext != ir::ArgumentExtension::None && ty_bits(ty) < 64 {
+                    assert_eq!(RegClass::I64, from_reg.get_class());
+                    let signed = match ext {
+                        ir::ArgumentExtension::Uext => false,
+                        ir::ArgumentExtension::Sext => true,
+                        _ => unreachable!(),
+                    };
+                    // Extend in place in the source register. Our convention is to
+                    // treat high bits as undefined for values in registers, so this
+                    // is safe, even for an argument that is nominally read-only.
+                    ctx.emit(Inst::Extend {
+                        rd: Writable::from_reg(from_reg),
+                        rn: from_reg,
+                        signed,
+                        from_bits: ty_bits(ty) as u8,
+                        to_bits: 64,
+                    });
+                }
                 ctx.emit(store_stack(MemArg::SPOffset(off, ty), from_reg, ty))
             }
         }
@@ -1487,8 +1539,10 @@ impl ABICall for AArch64ABICall {
         into_reg: Writable<Reg>,
     ) {
         match &self.sig.rets[idx] {
-            &ABIArg::Reg(reg, ty) => ctx.emit(Inst::gen_move(into_reg, reg.to_reg(), ty)),
+            // Extension mode doesn't matter because we're copying out, not in,
-            &ABIArg::Stack(off, ty) => {
+            // and we ignore high bits in our own registers by convention.
+            &ABIArg::Reg(reg, ty, _) => ctx.emit(Inst::gen_move(into_reg, reg.to_reg(), ty)),
+            &ABIArg::Stack(off, ty, _) => {
                 let ret_area_base = self.sig.stack_arg_space;
                 ctx.emit(load_stack(
                     MemArg::SPOffset(off + ret_area_base, ty),

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

@@ -23,8 +23,8 @@ static STACK_ARG_RET_SIZE_LIMIT: u64 = 128 * 1024 * 1024;
 
 #[derive(Clone, Debug)]
 enum ABIArg {
-    Reg(RealReg, ir::Type),
+    Reg(RealReg, ir::Type, ir::ArgumentExtension),
-    Stack(i64, ir::Type),
+    Stack(i64, ir::Type, ir::ArgumentExtension),
 }
 
 /// X64 ABI information shared between body (callee) and caller.
@@ -302,7 +302,7 @@ impl ABIBody for X64ABIBody {
     fn liveins(&self) -> Set<RealReg> {
         let mut set: Set<RealReg> = Set::empty();
         for arg in &self.sig.args {
-            if let &ABIArg::Reg(r, _) = arg {
+            if let &ABIArg::Reg(r, ..) = arg {
                 set.insert(r);
             }
         }
@@ -312,7 +312,7 @@ impl ABIBody for X64ABIBody {
     fn liveouts(&self) -> Set<RealReg> {
         let mut set: Set<RealReg> = Set::empty();
         for ret in &self.sig.rets {
-            if let &ABIArg::Reg(r, _) = ret {
+            if let &ABIArg::Reg(r, ..) = ret {
                 set.insert(r);
             }
         }
@@ -321,8 +321,8 @@ impl ABIBody for X64ABIBody {
 
     fn gen_copy_arg_to_reg(&self, idx: usize, to_reg: Writable<Reg>) -> Inst {
         match &self.sig.args[idx] {
-            ABIArg::Reg(from_reg, ty) => Inst::gen_move(to_reg, from_reg.to_reg(), *ty),
+            ABIArg::Reg(from_reg, ty, _) => Inst::gen_move(to_reg, from_reg.to_reg(), *ty),
-            &ABIArg::Stack(off, ty) => {
+            &ABIArg::Stack(off, ty, _) => {
                 assert!(
                     self.fp_to_arg_offset() + off <= u32::max_value() as i64,
                     "large offset nyi"
@@ -351,15 +351,10 @@ impl ABIBody for X64ABIBody {
         }
     }
 
-    fn gen_copy_reg_to_retval(
+    fn gen_copy_reg_to_retval(&self, idx: usize, from_reg: Writable<Reg>) -> Vec<Inst> {
-        &self,
-        idx: usize,
-        from_reg: Writable<Reg>,
-        ext: ArgumentExtension,
-    ) -> Vec<Inst> {
         let mut ret = Vec::new();
         match &self.sig.rets[idx] {
-            &ABIArg::Reg(r, ty) => {
+            &ABIArg::Reg(r, ty, ext) => {
                 let from_bits = ty.bits() as u8;
                 let ext_mode = match from_bits {
                     1 | 8 => Some(ExtMode::BQ),
@@ -391,7 +386,7 @@ impl ABIBody for X64ABIBody {
                 };
             }
 
-            &ABIArg::Stack(off, ty) => {
+            &ABIArg::Stack(off, ty, ext) => {
                 let from_bits = ty.bits() as u8;
                 let ext_mode = match from_bits {
                     1 | 8 => Some(ExtMode::BQ),
@@ -758,7 +753,7 @@ fn abisig_to_uses_and_defs(sig: &ABISig) -> (Vec<Reg>, Vec<Writable<Reg>>) {
     let mut uses = Vec::new();
     for arg in &sig.args {
         match arg {
-            &ABIArg::Reg(reg, _) => uses.push(reg.to_reg()),
+            &ABIArg::Reg(reg, ..) => uses.push(reg.to_reg()),
             _ => {}
         }
     }
@@ -767,7 +762,7 @@ fn abisig_to_uses_and_defs(sig: &ABISig) -> (Vec<Reg>, Vec<Writable<Reg>>) {
     let mut defs = get_caller_saves(sig.call_conv);
     for ret in &sig.rets {
         match ret {
-            &ABIArg::Reg(reg, _) => defs.push(Writable::from_reg(reg.to_reg())),
+            &ABIArg::Reg(reg, ..) => defs.push(Writable::from_reg(reg.to_reg())),
             _ => {}
         }
     }
@@ -781,11 +776,19 @@ fn try_fill_baldrdash_reg(call_conv: CallConv, param: &ir::AbiParam) -> Option<A
         match &param.purpose {
             &ir::ArgumentPurpose::VMContext => {
                 // This is SpiderMonkey's `WasmTlsReg`.
-                Some(ABIArg::Reg(regs::r14().to_real_reg(), ir::types::I64))
+                Some(ABIArg::Reg(
+                    regs::r14().to_real_reg(),
+                    ir::types::I64,
+                    param.extension,
+                ))
             }
             &ir::ArgumentPurpose::SignatureId => {
                 // This is SpiderMonkey's `WasmTableCallSigReg`.
-                Some(ABIArg::Reg(regs::r10().to_real_reg(), ir::types::I64))
+                Some(ABIArg::Reg(
+                    regs::r10().to_real_reg(),
+                    ir::types::I64,
+                    param.extension,
+                ))
             }
             _ => None,
         }
@@ -872,7 +875,11 @@ fn compute_arg_locs(
             assert!(intreg);
             ret.push(param);
         } else if let Some(reg) = candidate {
-            ret.push(ABIArg::Reg(reg.to_real_reg(), param.value_type));
+            ret.push(ABIArg::Reg(
+                reg.to_real_reg(),
+                param.value_type,
+                param.extension,
+            ));
             *next_reg += 1;
         } else {
             // Compute size. Every arg takes a minimum slot of 8 bytes. (16-byte
@@ -882,7 +889,11 @@ fn compute_arg_locs(
             // Align.
             debug_assert!(size.is_power_of_two());
             next_stack = (next_stack + size - 1) & !(size - 1);
-            ret.push(ABIArg::Stack(next_stack as i64, param.value_type));
+            ret.push(ABIArg::Stack(
+                next_stack as i64,
+                param.value_type,
+                param.extension,
+            ));
             next_stack += size;
         }
     }
@@ -894,9 +905,17 @@ fn compute_arg_locs(
     let extra_arg = if add_ret_area_ptr {
         debug_assert!(args_or_rets == ArgsOrRets::Args);
         if let Some(reg) = get_intreg_for_arg_systemv(&call_conv, next_gpr) {
-            ret.push(ABIArg::Reg(reg.to_real_reg(), ir::types::I64));
+            ret.push(ABIArg::Reg(
+                reg.to_real_reg(),
+                ir::types::I64,
+                ir::ArgumentExtension::None,
+            ));
         } else {
-            ret.push(ABIArg::Stack(next_stack as i64, ir::types::I64));
+            ret.push(ABIArg::Stack(
+                next_stack as i64,
+                ir::types::I64,
+                ir::ArgumentExtension::None,
+            ));
             next_stack += 8;
         }
         Some(ret.len() - 1)
@@ -1125,12 +1144,74 @@ impl ABICall for X64ABICall {
         from_reg: Reg,
     ) {
         match &self.sig.args[idx] {
-            &ABIArg::Reg(reg, ty) => ctx.emit(Inst::gen_move(
+            &ABIArg::Reg(reg, ty, ext) if ext != ir::ArgumentExtension::None && ty.bits() < 64 => {
+                assert_eq!(RegClass::I64, reg.get_class());
+                let dest_reg = Writable::from_reg(reg.to_reg());
+                let ext_mode = match ty.bits() {
+                    1 | 8 => ExtMode::BQ,
+                    16 => ExtMode::WQ,
+                    32 => ExtMode::LQ,
+                    _ => unreachable!(),
+                };
+                match ext {
+                    ir::ArgumentExtension::Uext => {
+                        ctx.emit(Inst::movzx_rm_r(
+                            ext_mode,
+                            RegMem::reg(from_reg),
+                            dest_reg,
+                            /* infallible load */ None,
+                        ));
+                    }
+                    ir::ArgumentExtension::Sext => {
+                        ctx.emit(Inst::movsx_rm_r(
+                            ext_mode,
+                            RegMem::reg(from_reg),
+                            dest_reg,
+                            /* infallible load */ None,
+                        ));
+                    }
+                    _ => unreachable!(),
+                };
+            }
+            &ABIArg::Reg(reg, ty, _) => ctx.emit(Inst::gen_move(
                 Writable::from_reg(reg.to_reg()),
                 from_reg,
                 ty,
             )),
-            &ABIArg::Stack(off, ty) => {
+            &ABIArg::Stack(off, ty, ext) => {
+                if ext != ir::ArgumentExtension::None && ty.bits() < 64 {
+                    assert_eq!(RegClass::I64, from_reg.get_class());
+                    let dest_reg = Writable::from_reg(from_reg);
+                    let ext_mode = match ty.bits() {
+                        1 | 8 => ExtMode::BQ,
+                        16 => ExtMode::WQ,
+                        32 => ExtMode::LQ,
+                        _ => unreachable!(),
+                    };
+                    // Extend in place in the source register. Our convention is to
+                    // treat high bits as undefined for values in registers, so this
+                    // is safe, even for an argument that is nominally read-only.
+                    match ext {
+                        ir::ArgumentExtension::Uext => {
+                            ctx.emit(Inst::movzx_rm_r(
+                                ext_mode,
+                                RegMem::reg(from_reg),
+                                dest_reg,
+                                /* infallible load */ None,
+                            ));
+                        }
+                        ir::ArgumentExtension::Sext => {
+                            ctx.emit(Inst::movsx_rm_r(
+                                ext_mode,
+                                RegMem::reg(from_reg),
+                                dest_reg,
+                                /* infallible load */ None,
+                            ));
+                        }
+                        _ => unreachable!(),
+                    };
+                }
+
                 debug_assert!(off <= u32::max_value() as i64);
                 debug_assert!(off >= 0);
                 ctx.emit(store_stack(
@@ -1149,8 +1230,8 @@ impl ABICall for X64ABICall {
         into_reg: Writable<Reg>,
     ) {
         match &self.sig.rets[idx] {
-            &ABIArg::Reg(reg, ty) => ctx.emit(Inst::gen_move(into_reg, reg.to_reg(), ty)),
+            &ABIArg::Reg(reg, ty, _) => ctx.emit(Inst::gen_move(into_reg, reg.to_reg(), ty)),
-            &ABIArg::Stack(off, ty) => {
+            &ABIArg::Stack(off, ty, _) => {
                 let ret_area_base = self.sig.stack_arg_space;
                 let sp_offset = off + ret_area_base;
                 // TODO handle offsets bigger than u32::max

cranelift/codegen/src/machinst/abi.rs

@@ -1,7 +1,7 @@
 //! ABI definitions.
 
 use crate::binemit::Stackmap;
-use crate::ir::{ArgumentExtension, StackSlot};
+use crate::ir::StackSlot;
 use crate::machinst::*;
 use crate::settings;
 
@@ -52,12 +52,7 @@ pub trait ABIBody {
     fn gen_retval_area_setup(&self) -> Option<Self::I>;
 
     /// Generate an instruction which copies a source register to a return value slot.
-    fn gen_copy_reg_to_retval(
+    fn gen_copy_reg_to_retval(&self, idx: usize, from_reg: Writable<Reg>) -> Vec<Self::I>;
-        &self,
-        idx: usize,
-        from_reg: Writable<Reg>,
-        ext: ArgumentExtension,
-    ) -> Vec<Self::I>;
 
     /// Generate a return instruction.
     fn gen_ret(&self) -> Self::I;

cranelift/codegen/src/machinst/lower.rs

@@ -8,9 +8,8 @@ use crate::inst_predicates::{has_side_effect_or_load, is_constant_64bit};
 use crate::ir::instructions::BranchInfo;
 use crate::ir::types::I64;
 use crate::ir::{
-    ArgumentExtension, ArgumentPurpose, Block, Constant, ConstantData, ExternalName, Function,
+    ArgumentPurpose, Block, Constant, ConstantData, ExternalName, Function, GlobalValueData, Inst,
-    GlobalValueData, Inst, InstructionData, MemFlags, Opcode, Signature, SourceLoc, Type, Value,
+    InstructionData, MemFlags, Opcode, Signature, SourceLoc, Type, Value, ValueDef,
-    ValueDef,
 };
 use crate::machinst::{
     ABIBody, BlockIndex, BlockLoweringOrder, LoweredBlock, MachLabel, VCode, VCodeBuilder,
@@ -232,7 +231,7 @@ pub struct Lower<'func, I: VCodeInst> {
     value_regs: SecondaryMap<Value, Reg>,
 
     /// Return-value vregs.
-    retval_regs: Vec<(Reg, ArgumentExtension)>,
+    retval_regs: Vec<Reg>,
 
     /// Instruction colors.
     inst_colors: SecondaryMap<Inst, InstColor>,
@@ -354,7 +353,7 @@ impl<'func, I: VCodeInst> Lower<'func, I> {
             next_vreg += 1;
             let regclass = I::rc_for_type(ret.value_type)?;
             let vreg = Reg::new_virtual(regclass, v);
-            retval_regs.push((vreg, ret.extension));
+            retval_regs.push(vreg);
             vcode.set_vreg_type(vreg.as_virtual_reg().unwrap(), ret.value_type);
         }
 
@@ -427,9 +426,9 @@ impl<'func, I: VCodeInst> Lower<'func, I> {
 
     fn gen_retval_setup(&mut self, gen_ret_inst: GenerateReturn) {
         let retval_regs = self.retval_regs.clone();
-        for (i, (reg, ext)) in retval_regs.into_iter().enumerate() {
+        for (i, reg) in retval_regs.into_iter().enumerate() {
             let reg = Writable::from_reg(reg);
-            let insns = self.vcode.abi().gen_copy_reg_to_retval(i, reg, ext);
+            let insns = self.vcode.abi().gen_copy_reg_to_retval(i, reg);
             for insn in insns {
                 self.emit(insn);
             }
@@ -844,7 +843,7 @@ impl<'func, I: VCodeInst> LowerCtx for Lower<'func, I> {
     }
 
     fn retval(&self, idx: usize) -> Writable<Reg> {
-        Writable::from_reg(self.retval_regs[idx].0)
+        Writable::from_reg(self.retval_regs[idx])
     }
 
     fn get_vm_context(&self) -> Option<Reg> {

cranelift/filetests/filetests/vcode/aarch64/call.clif

@@ -1,7 +1,7 @@
 test compile
 target aarch64
 
-function %f(i64) -> i64 {
+function %f1(i64) -> i64 {
     fn0 = %g(i64) -> i64
 
 block0(v0: i64):
@@ -16,3 +16,61 @@ block0(v0: i64):
 ; nextln:  mov sp, fp
 ; nextln:  ldp fp, lr, [sp], #16
 ; nextln:  ret
+
+function %f2(i32) -> i64 {
+    fn0 = %g(i32 uext) -> i64
+
+block0(v0: i32):
+    v1 = call fn0(v0)
+    return v1
+}
+
+; check:  stp fp, lr, [sp, #-16]!
+; nextln:  mov fp, sp
+; nextln:  mov w0, w0
+; nextln:  ldr x16, 8 ; b 12 ; data
+; nextln:  blr x16
+; nextln:  mov sp, fp
+; nextln:  ldp fp, lr, [sp], #16
+; nextln:  ret
+
+function %f3(i32) -> i32 uext {
+block0(v0: i32):
+    return v0
+}
+
+; check:  stp fp, lr, [sp, #-16]!
+; nextln:  mov fp, sp
+; nextln:  mov w0, w0
+; nextln:  mov sp, fp
+; nextln:  ldp fp, lr, [sp], #16
+; nextln:  ret
+
+function %f4(i32) -> i64 {
+    fn0 = %g(i32 sext) -> i64
+
+block0(v0: i32):
+    v1 = call fn0(v0)
+    return v1
+}
+
+; check:  stp fp, lr, [sp, #-16]!
+; nextln:  mov fp, sp
+; nextln:  sxtw x0, w0
+; nextln:  ldr x16, 8 ; b 12 ; data
+; nextln:  blr x16
+; nextln:  mov sp, fp
+; nextln:  ldp fp, lr, [sp], #16
+; nextln:  ret
+
+function %f3(i32) -> i32 sext {
+block0(v0: i32):
+    return v0
+}
+
+; check:  stp fp, lr, [sp, #-16]!
+; nextln:  mov fp, sp
+; nextln:  sxtw x0, w0
+; nextln:  mov sp, fp
+; nextln:  ldp fp, lr, [sp], #16
+; nextln:  ret