Merge pull request #1999 from bnjbvr/fix-aarch64-ishl-by-zero

machinst aarch64: fix encoding generation of left-shift by 0

Author: cfallin

cranelift/codegen/src/isa/aarch64/inst/emit.rs

@@ -534,8 +534,16 @@ impl MachInstEmit for Inst {
                     ALUOp::Lsr64 => (0b1101001101, u32::from(amt), 0b111111),
                     ALUOp::Asr32 => (0b0001001100, u32::from(amt), 0b011111),
                     ALUOp::Asr64 => (0b1001001101, u32::from(amt), 0b111111),
-                    ALUOp::Lsl32 => (0b0101001100, u32::from(32 - amt), u32::from(31 - amt)),
-                    ALUOp::Lsl64 => (0b1101001101, u32::from(64 - amt), u32::from(63 - amt)),
+                    ALUOp::Lsl32 => (
+                        0b0101001100,
+                        u32::from((32 - amt) % 32),
+                        u32::from(31 - amt),
+                    ),
+                    ALUOp::Lsl64 => (
+                        0b1101001101,
+                        u32::from((64 - amt) % 64),
+                        u32::from(63 - amt),
+                    ),
                     _ => unimplemented!("{:?}", alu_op),
                 };
                 sink.put4(

cranelift/codegen/src/isa/aarch64/inst/emit_tests.rs

@@ -934,6 +934,26 @@ fn test_aarch64_binemit() {
         "280141D3",
         "lsl x8, x9, #63",
     ));
+    insns.push((
+        Inst::AluRRImmShift {
+            alu_op: ALUOp::Lsl32,
+            rd: writable_xreg(10),
+            rn: xreg(11),
+            immshift: ImmShift::maybe_from_u64(0).unwrap(),
+        },
+        "6A7D0053",
+        "lsl w10, w11, #0",
+    ));
+    insns.push((
+        Inst::AluRRImmShift {
+            alu_op: ALUOp::Lsl64,
+            rd: writable_xreg(10),
+            rn: xreg(11),
+            immshift: ImmShift::maybe_from_u64(0).unwrap(),
+        },
+        "6AFD40D3",
+        "lsl x10, x11, #0",
+    ));
 
     insns.push((
         Inst::AluRRImmLogic {