[MIR,test] Change llc -march=x86-64 to -mtriple=x86_64

Similar to 806761a

-mtriple= specifies the full target triple while -march= merely sets the
architecture part of the default target triple (e.g. Windows, macOS).

Therefore, -march= is error-prone and not recommended for tests without
a target triple. The issue has been benign as these MIR tests do not
utilize object file format specific detail, but it's good to change
these tests to neighbor files that use -mtriple=x86_64

Author: MaskRay

llvm/test/CodeGen/MIR/X86/basic-block-liveins.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=x86_64 -run-pass none -o - %s | FileCheck %s
 # This test ensures that the MIR parser parses basic block liveins correctly.
 
 --- |

llvm/test/CodeGen/MIR/X86/basic-block-not-at-start-of-line-error.mir

@@ -1,4 +1,4 @@
-# RUN: not llc -march=x86-64 -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
+# RUN: not llc -mtriple=x86_64 -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
 
 --- |
 

llvm/test/CodeGen/MIR/X86/block-address-operands.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=x86_64 -run-pass none -o - %s | FileCheck %s
 # This test ensures that the MIR parser parses the block address operands
 # correctly.
 

llvm/test/CodeGen/MIR/X86/callee-saved-info.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=x86_64 -run-pass none -o - %s | FileCheck %s
 # This test ensures that the MIR parser parses callee saved information in the
 # stack objects correctly.
 

llvm/test/CodeGen/MIR/X86/cfi-def-cfa-offset.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=x86_64 -run-pass none -o - %s | FileCheck %s
 # This test ensures that the MIR parser parses the cfi offset operands
 # correctly.
 

llvm/test/CodeGen/MIR/X86/cfi-def-cfa-register.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=x86_64 -run-pass none -o - %s | FileCheck %s
 # This test ensures that the MIR parser parses the cfi def_cfa_register
 # operands correctly.
 

llvm/test/CodeGen/MIR/X86/cfi-offset.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=x86_64 -run-pass none -o - %s | FileCheck %s
 # This test ensures that the MIR parser parses the cfi offset operands
 # correctly.
 

llvm/test/CodeGen/MIR/X86/constant-pool-item-redefinition-error.mir

@@ -1,4 +1,4 @@
-# RUN: not llc -march=x86-64 -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
+# RUN: not llc -mtriple=x86_64 -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
 
 --- |
 

llvm/test/CodeGen/MIR/X86/constant-pool.mir

@@ -1,4 +1,4 @@
-# RUN: llc -march=x86-64 -run-pass none -o - %s | FileCheck %s
+# RUN: llc -mtriple=x86_64 -run-pass none -o - %s | FileCheck %s
 # This test ensures that the MIR parser parses constant pool constants and
 # constant pool operands correctly.
 

llvm/test/CodeGen/MIR/X86/constant-value-error.mir

@@ -1,4 +1,4 @@
-# RUN: not llc -march=x86-64 -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
+# RUN: not llc -mtriple=x86_64 -run-pass none -o /dev/null %s 2>&1 | FileCheck %s
 # This test ensures that the MIR parser reports an error when parsing an invalid
 # constant value.