diff --git a/cranelift/codegen/src/isa/riscv64/inst.isle b/cranelift/codegen/src/isa/riscv64/inst.isle
index ca27ac8c5f..4cee85ed5d 100644
--- a/cranelift/codegen/src/isa/riscv64/inst.isle
+++ b/cranelift/codegen/src/isa/riscv64/inst.isle
@@ -1910,21 +1910,20 @@
 (decl lower_cond_br (IntCC ValueRegs VecMachLabel Type) Unit)
 (extern constructor lower_cond_br lower_cond_br)
 
+(decl intcc_to_extend_op (IntCC) ExtendOp)
+(extern constructor intcc_to_extend_op intcc_to_extend_op)
+
 ;; Normalize a value for comparision.
 ;;
 ;; This ensures that types smaller than a register don't accidentally
 ;; pass undefined high bits when being compared as a full register.
-(decl normalize_cmp_value (Type ValueRegs) ValueRegs)
+(decl normalize_cmp_value (Type ValueRegs ExtendOp) ValueRegs)
 
-(rule (normalize_cmp_value $I8 r)
-      (value_reg (alu_rr_imm12 (AluOPRRI.Andi) r (imm12_const 255))))
-(rule (normalize_cmp_value $I16 r)
-      (value_reg (alu_rrr (AluOPRRR.And) r (imm $I16 65535))))
-(rule (normalize_cmp_value $I32 r)
-      (value_reg (alu_rr_imm12 (AluOPRRI.Addiw) r (imm12_const 0))))
+(rule 1 (normalize_cmp_value (fits_in_32 ity) r op)
+      (extend r op ity $I64))
 
-(rule (normalize_cmp_value $I64  r) r)
-(rule (normalize_cmp_value $I128 r) r)
+(rule (normalize_cmp_value $I64  r _) r)
+(rule (normalize_cmp_value $I128 r _) r)
 
 ;; Convert a truthy value, possibly of more than one register (an
 ;; I128), to one register. If narrower than 64 bits, must have already
@@ -1940,7 +1939,7 @@
 ;; Default behavior for branching based on an input value.
 (rule
   (lower_branch (brif v @ (value_type ty) _ _) targets)
-  (lower_cond_br (IntCC.NotEqual) (normalize_cmp_value ty v) targets ty))
+  (lower_cond_br (IntCC.NotEqual) (normalize_cmp_value ty v (ExtendOp.Zero)) targets ty))
 
 ;; Special case for SI128 to reify the comparison value and branch on it.
 (rule 2
@@ -2118,7 +2117,7 @@
 (rule
   0
   (lower_bmask (fits_in_64 _) (fits_in_64 in_ty) val)
-  (let ((input Reg (normalize_cmp_value in_ty val))
+  (let ((input Reg (normalize_cmp_value in_ty val (ExtendOp.Zero)))
         (zero Reg (zero_reg))
         (ones Reg (load_imm12 -1)))
   (value_reg (gen_select_reg (IntCC.Equal) zero input zero ones))))
diff --git a/cranelift/codegen/src/isa/riscv64/inst/unwind/systemv.rs b/cranelift/codegen/src/isa/riscv64/inst/unwind/systemv.rs
index d62d8ba4af..1803ecfec1 100644
--- a/cranelift/codegen/src/isa/riscv64/inst/unwind/systemv.rs
+++ b/cranelift/codegen/src/isa/riscv64/inst/unwind/systemv.rs
@@ -143,7 +143,7 @@ mod tests {
 
         assert_eq!(
             format!("{:?}", fde),
-            "FrameDescriptionEntry { address: Constant(4321), length: 16, lsda: None, instructions: [] }"
+            "FrameDescriptionEntry { address: Constant(4321), length: 20, lsda: None, instructions: [] }"
         );
     }
 
diff --git a/cranelift/codegen/src/isa/riscv64/lower.isle b/cranelift/codegen/src/isa/riscv64/lower.isle
index 9d1f43af57..b08d6558f6 100644
--- a/cranelift/codegen/src/isa/riscv64/lower.isle
+++ b/cranelift/codegen/src/isa/riscv64/lower.isle
@@ -626,12 +626,12 @@
 ;;;;;  Rules for `select`;;;;;;;;;
 (rule
   (lower (has_type ty (select c @ (value_type cty) x y)))
-  (gen_select ty (truthy_to_reg cty (normalize_cmp_value cty c)) x y))
+  (gen_select ty (truthy_to_reg cty (normalize_cmp_value cty c (ExtendOp.Zero))) x y))
 
 (rule 1
   (lower (has_type (fits_in_64 ty) (select (icmp cc a b @ (value_type in_ty)) x y)))
-  (let ((a Reg (normalize_cmp_value in_ty a))
-        (b Reg (normalize_cmp_value in_ty b)))
+  (let ((a Reg (normalize_cmp_value in_ty a (intcc_to_extend_op cc)))
+        (b Reg (normalize_cmp_value in_ty b (intcc_to_extend_op cc))))
     (gen_select_reg cc a b x y)))
 
 ;;;;;  Rules for `bitselect`;;;;;;;;;
@@ -851,7 +851,7 @@
 
 (rule -1
   (lower (has_type ty (select_spectre_guard c @ (value_type cty) x y)))
-  (gen_select ty (truthy_to_reg cty (normalize_cmp_value cty c)) x y))
+  (gen_select ty (truthy_to_reg cty (normalize_cmp_value cty c (ExtendOp.Zero))) x y))
 
 ;;;;;  Rules for `bmask`;;;;;;;;;
 (rule
diff --git a/cranelift/codegen/src/isa/riscv64/lower/isle.rs b/cranelift/codegen/src/isa/riscv64/lower/isle.rs
index f1b3fed927..1c088b4bea 100644
--- a/cranelift/codegen/src/isa/riscv64/lower/isle.rs
+++ b/cranelift/codegen/src/isa/riscv64/lower/isle.rs
@@ -3,7 +3,7 @@
 // Pull in the ISLE generated code.
 #[allow(unused)]
 pub mod generated_code;
-use generated_code::{Context, MInst};
+use generated_code::{Context, ExtendOp, MInst};
 
 // Types that the generated ISLE code uses via `use super::*`.
 use super::{writable_zero_reg, zero_reg};
@@ -60,7 +60,22 @@ impl generated_code::Context for IsleContext<'_, '_, MInst, Riscv64Backend> {
             _ => unreachable!(),
         }
     }
+    fn intcc_to_extend_op(&mut self, cc: &IntCC) -> ExtendOp {
+        use IntCC::*;
+        match *cc {
+            Equal
+            | NotEqual
+            | UnsignedLessThan
+            | UnsignedGreaterThanOrEqual
+            | UnsignedGreaterThan
+            | UnsignedLessThanOrEqual => ExtendOp::Zero,
 
+            SignedLessThan
+            | SignedGreaterThanOrEqual
+            | SignedGreaterThan
+            | SignedLessThanOrEqual => ExtendOp::Signed,
+        }
+    }
     fn lower_cond_br(
         &mut self,
         cc: &IntCC,
diff --git a/cranelift/filetests/filetests/isa/riscv64/cold-blocks.clif b/cranelift/filetests/filetests/isa/riscv64/cold-blocks.clif
index 0b7a8cde0f..bfaab03348 100644
--- a/cranelift/filetests/filetests/isa/riscv64/cold-blocks.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/cold-blocks.clif
@@ -16,8 +16,9 @@ block2:
 
 ; VCode:
 ; block0:
-;   sext.w a2,a0
-;   bne a2,zero,taken(label1),not_taken(label2)
+;   slli a2,a0,32
+;   srli a4,a2,32
+;   bne a4,zero,taken(label1),not_taken(label2)
 ; block1:
 ;   j label3
 ; block2:
@@ -28,11 +29,12 @@ block2:
 ; 
 ; Disassembled:
 ; block0: ; offset 0x0
-;   sext.w a2, a0
-;   bnez a2, 8
-; block1: ; offset 0x8
+;   slli a2, a0, 0x20
+;   srli a4, a2, 0x20
+;   bnez a4, 8
+; block1: ; offset 0xc
 ;   addi a0, zero, 0x61
-; block2: ; offset 0xc
+; block2: ; offset 0x10
 ;   ret
 
 function %cold_annotation(i32) -> i32 {
@@ -49,8 +51,9 @@ block2 cold:
 
 ; VCode:
 ; block0:
-;   sext.w a2,a0
-;   bne a2,zero,taken(label1),not_taken(label2)
+;   slli a2,a0,32
+;   srli a4,a2,32
+;   bne a4,zero,taken(label1),not_taken(label2)
 ; block1:
 ;   j label3
 ; block3:
@@ -61,11 +64,12 @@ block2 cold:
 ; 
 ; Disassembled:
 ; block0: ; offset 0x0
-;   sext.w a2, a0
-;   beqz a2, 8
-; block1: ; offset 0x8
+;   slli a2, a0, 0x20
+;   srli a4, a2, 0x20
+;   beqz a4, 8
+; block1: ; offset 0xc
 ;   ret
-; block2: ; offset 0xc
+; block2: ; offset 0x10
 ;   addi a0, zero, 0x61
 ;   j -8
 
diff --git a/cranelift/filetests/filetests/isa/riscv64/condbr.clif b/cranelift/filetests/filetests/isa/riscv64/condbr.clif
index 3a0c18efeb..617afdfe00 100644
--- a/cranelift/filetests/filetests/isa/riscv64/condbr.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/condbr.clif
@@ -675,10 +675,9 @@ block1:
 
 ; VCode:
 ; block0:
-;   lui a1,16
-;   addi a1,a1,4095
-;   and a3,a0,a1
-;   bne a3,zero,taken(label1),not_taken(label2)
+;   slli t2,a0,48
+;   srli a1,t2,48
+;   bne a1,zero,taken(label1),not_taken(label2)
 ; block1:
 ;   j label3
 ; block2:
@@ -688,10 +687,9 @@ block1:
 ; 
 ; Disassembled:
 ; block0: ; offset 0x0
-;   lui a1, 0x10
-;   addi a1, a1, -1
-;   and a3, a0, a1
-; block1: ; offset 0xc
+;   slli t2, a0, 0x30
+;   srli a1, t2, 0x30
+; block1: ; offset 0x8
 ;   ret
 
 function %i32_brif(i32){
@@ -705,8 +703,9 @@ block1:
 
 ; VCode:
 ; block0:
-;   sext.w t2,a0
-;   bne t2,zero,taken(label1),not_taken(label2)
+;   slli t2,a0,32
+;   srli a1,t2,32
+;   bne a1,zero,taken(label1),not_taken(label2)
 ; block1:
 ;   j label3
 ; block2:
@@ -716,8 +715,9 @@ block1:
 ; 
 ; Disassembled:
 ; block0: ; offset 0x0
-;   sext.w t2, a0
-; block1: ; offset 0x4
+;   slli t2, a0, 0x20
+;   srli a1, t2, 0x20
+; block1: ; offset 0x8
 ;   ret
 
 function %i64_brif(i64){
diff --git a/cranelift/filetests/filetests/isa/riscv64/condops.clif b/cranelift/filetests/filetests/isa/riscv64/condops.clif
index 35bd747ef9..c2c1334efe 100644
--- a/cranelift/filetests/filetests/isa/riscv64/condops.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/condops.clif
@@ -108,18 +108,22 @@ block0(v0: i32, v1: i8, v2: i8):
 
 ; VCode:
 ; block0:
-;   sext.w a3,a0
-;   li a4,42
-;   sext.w a5,a4
-;   select_reg a0,a1,a2##condition=(a3 eq a5)
+;   slli a3,a0,32
+;   srli a3,a3,32
+;   li a5,42
+;   slli a7,a5,32
+;   srli t4,a7,32
+;   select_reg a0,a1,a2##condition=(a3 eq t4)
 ;   ret
 ; 
 ; Disassembled:
 ; block0: ; offset 0x0
-;   sext.w a3, a0
-;   addi a4, zero, 0x2a
-;   sext.w a5, a4
-;   beq a3, a5, 0xc
+;   slli a3, a0, 0x20
+;   srli a3, a3, 0x20
+;   addi a5, zero, 0x2a
+;   slli a7, a5, 0x20
+;   srli t4, a7, 0x20
+;   beq a3, t4, 0xc
 ;   ori a0, a2, 0
 ;   j 8
 ;   ori a0, a1, 0
diff --git a/cranelift/filetests/filetests/isa/riscv64/i128-bmask.clif b/cranelift/filetests/filetests/isa/riscv64/i128-bmask.clif
index 967338b903..e802e74d8c 100644
--- a/cranelift/filetests/filetests/isa/riscv64/i128-bmask.clif
+++ b/cranelift/filetests/filetests/isa/riscv64/i128-bmask.clif
@@ -150,17 +150,20 @@ block0(v0: i32):
 
 ; VCode:
 ; block0:
-;   sext.w t2,a0
-;   li a1,-1
-;   select_reg a1,zero,a1##condition=(zero eq t2)
+;   slli t2,a0,32
+;   srli a1,t2,32
+;   li a3,-1
+;   select_reg a1,zero,a3##condition=(zero eq a1)
 ;   mv a0,a1
 ;   ret
 ; 
 ; Disassembled:
 ; block0: ; offset 0x0
-;   sext.w t2, a0
-;   addi a1, zero, -1
-;   beq zero, t2, 8
+;   slli t2, a0, 0x20
+;   srli a1, t2, 0x20
+;   addi a3, zero, -1
+;   beq zero, a1, 0xc
+;   ori a1, a3, 0
 ;   j 8
 ;   ori a1, zero, 0
 ;   ori a0, a1, 0
@@ -174,22 +177,20 @@ block0(v0: i16):
 
 ; VCode:
 ; block0:
-;   lui a1,16
-;   addi a1,a1,4095
-;   and a3,a0,a1
-;   li a5,-1
-;   select_reg a1,zero,a5##condition=(zero eq a3)
+;   slli t2,a0,48
+;   srli a1,t2,48
+;   li a3,-1
+;   select_reg a1,zero,a3##condition=(zero eq a1)
 ;   mv a0,a1
 ;   ret
 ; 
 ; Disassembled:
 ; block0: ; offset 0x0
-;   lui a1, 0x10
-;   addi a1, a1, -1
-;   and a3, a0, a1
-;   addi a5, zero, -1
-;   beq zero, a3, 0xc
-;   ori a1, a5, 0
+;   slli t2, a0, 0x30
+;   srli a1, t2, 0x30
+;   addi a3, zero, -1
+;   beq zero, a1, 0xc
+;   ori a1, a3, 0
 ;   j 8
 ;   ori a1, zero, 0
 ;   ori a0, a1, 0
diff --git a/cranelift/filetests/filetests/runtests/issue5839.clif b/cranelift/filetests/filetests/runtests/issue5839.clif
new file mode 100644
index 0000000000..4e2a2c391a
--- /dev/null
+++ b/cranelift/filetests/filetests/runtests/issue5839.clif
@@ -0,0 +1,20 @@
+test interpret
+test run
+set opt_level=speed
+target aarch64
+target s390x
+target x86_64
+target riscv64
+
+function %a(i8, i8) -> i32 {
+block0(v0: i8, v1: i8):
+    v2 = icmp sle v0, v1
+    v3 = uextend.i32 v2
+    v4 = iconst.i32 0
+    v5 = iconst.i32 1
+    v6 = icmp.i32 eq v3, v4  ; v4 = 0
+    v7 = select v6, v5, v3  ; v5 = 1
+    return v7
+}
+
+; run: %a(20, -11) == 1
\ No newline at end of file