cranelift: Implement scalar ireduce on interpreter (#4320)

cranelift/filetests/filetests/runtests/i128-ireduce.clif

@@ -1,3 +1,4 @@
+test interpret
 test run
 set enable_llvm_abi_extensions=true
 target aarch64

cranelift/filetests/filetests/runtests/ireduce.clif

@@ -0,0 +1,58 @@
+test interpret
+test run
+target aarch64
+target x86_64
+
+function %ireduce_i16_i8(i16) -> i8 {
+block0(v0: i16):
+  v1 = ireduce.i8 v0
+  return v1
+}
+; run: %ireduce_i16_i8(0xFF00) == 0x00
+; run: %ireduce_i16_i8(0x0042) == 0x42
+; run: %ireduce_i16_i8(0xFFFF) == 0xFF
+
+function %ireduce_i32_i8(i32) -> i8 {
+block0(v0: i32):
+  v1 = ireduce.i8 v0
+  return v1
+}
+; run: %ireduce_i32_i8(0xFFFFFF00) == 0x00
+; run: %ireduce_i32_i8(0x00000042) == 0x42
+; run: %ireduce_i32_i8(0xFFFFFFFF) == 0xFF
+
+function %ireduce_i32_i16(i32) -> i16 {
+block0(v0: i32):
+  v1 = ireduce.i16 v0
+  return v1
+}
+; run: %ireduce_i32_i16(0xFFFF0000) == 0x0000
+; run: %ireduce_i32_i16(0x00004242) == 0x4242
+; run: %ireduce_i32_i16(0xFFFFFFFF) == 0xFFFF
+
+function %ireduce_i64_i8(i64) -> i8 {
+block0(v0: i64):
+  v1 = ireduce.i8 v0
+  return v1
+}
+; run: %ireduce_i64_i8(0xFFFFFFFF_FFFFFF00) == 0x00
+; run: %ireduce_i64_i8(0x00000000_00000042) == 0x42
+; run: %ireduce_i64_i8(0xFFFFFFFF_FFFFFFFF) == 0xFF
+
+function %ireduce_i64_i16(i64) -> i16 {
+block0(v0: i64):
+  v1 = ireduce.i16 v0
+  return v1
+}
+; run: %ireduce_i64_i16(0xFFFFFFFF_FFFF0000) == 0x0000
+; run: %ireduce_i64_i16(0x00000000_00004242) == 0x4242
+; run: %ireduce_i64_i16(0xFFFFFFFF_FFFFFFFF) == 0xFFFF
+
+function %ireduce_i64_i32(i64) -> i32 {
+block0(v0: i64):
+  v1 = ireduce.i32 v0
+  return v1
+}
+; run: %ireduce_i64_i32(0xFFFFFFFF_00000000) == 0x00000000
+; run: %ireduce_i64_i32(0x00000000_42424242) == 0x42424242
+; run: %ireduce_i64_i32(0xFFFFFFFF_FFFFFFFF) == 0xFFFFFFFF