Restrict test to x64.

Author: cjgillot

tests/mir-opt/pre-codegen/checked_ops.checked_shl.PreCodegen.after.mir

@@ -4,7 +4,7 @@ fn checked_shl(_1: u32, _2: u32) -> Option<u32> {
     debug x => _1;                       // in scope 0 at $DIR/checked_ops.rs:+0:20: +0:21
     debug rhs => _2;                     // in scope 0 at $DIR/checked_ops.rs:+0:28: +0:31
     let mut _0: std::option::Option<u32>; // return place in scope 0 at $DIR/checked_ops.rs:+0:41: +0:52
-    scope 1 (inlined core::num::<impl u32>::checked_shl) { // at $DIR/checked_ops.rs:15:7: 15:23
+    scope 1 (inlined core::num::<impl u32>::checked_shl) { // at $DIR/checked_ops.rs:16:7: 16:23
         debug self => _1;                // in scope 1 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
         debug rhs => _2;                 // in scope 1 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
         let mut _13: (u32, bool);        // in scope 1 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL

tests/mir-opt/pre-codegen/checked_ops.ilog2.PreCodegen.after.mir

@@ -3,7 +3,7 @@
 fn ilog2(_1: u32) -> u32 {
     debug x => _1;                       // in scope 0 at $DIR/checked_ops.rs:+0:14: +0:15
     let mut _0: u32;                     // return place in scope 0 at $DIR/checked_ops.rs:+0:25: +0:28
-    scope 1 (inlined #[track_caller] core::num::<impl u32>::ilog2) { // at $DIR/checked_ops.rs:20:7: 20:14
+    scope 1 (inlined #[track_caller] core::num::<impl u32>::ilog2) { // at $DIR/checked_ops.rs:21:7: 21:14
         debug self => _1;                // in scope 1 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
         let mut _2: std::option::Option<u32>; // in scope 1 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL
         let mut _3: isize;               // in scope 1 at $SRC_DIR/core/src/num/uint_macros.rs:LL:COL

tests/mir-opt/pre-codegen/checked_ops.rs

@@ -1,6 +1,7 @@
 // compile-flags: -O -Zmir-opt-level=2 -Cdebuginfo=2
 // needs-unwind
 // ignore-debug
+// only-x86_64
 
 #![crate_type = "lib"]
 #![feature(step_trait)]

tests/mir-opt/pre-codegen/checked_ops.step_forward.PreCodegen.after.mir

@@ -4,7 +4,7 @@ fn step_forward(_1: u32, _2: usize) -> u32 {
     debug x => _1;                       // in scope 0 at $DIR/checked_ops.rs:+0:21: +0:22
     debug n => _2;                       // in scope 0 at $DIR/checked_ops.rs:+0:29: +0:30
     let mut _0: u32;                     // return place in scope 0 at $DIR/checked_ops.rs:+0:42: +0:45
-    scope 1 (inlined <u32 as Step>::forward) { // at $DIR/checked_ops.rs:10:5: 10:35
+    scope 1 (inlined <u32 as Step>::forward) { // at $DIR/checked_ops.rs:11:5: 11:35
         debug start => _1;               // in scope 1 at $SRC_DIR/core/src/iter/range.rs:LL:COL
         debug n => _2;                   // in scope 1 at $SRC_DIR/core/src/iter/range.rs:LL:COL
         let _3: std::option::Option<u32>; // in scope 1 at $SRC_DIR/core/src/iter/range.rs:LL:COL