[llvm] [RegAlloc][AArch64] Add test case for terminal rule. NFC (PR #170035)

[via llvm-commits]

https://github.com/hstk30-hw created https://github.com/llvm/llvm-project/pull/170035

Add testcase for terminal rule(https://github.com/llvm/llvm-project/pull/169219)

>From 49ca8a9fa1369b2387f6635aeb9f18f8d8748841 Mon Sep 17 00:00:00 2001
From: hstk30 <hanwei62 at huawei.com>
Date: Sun, 30 Nov 2025 22:07:22 +0800
Subject: [PATCH] [RegAlloc][AArch64] Add test case for terminal rule. NFC

---
 .../CodeGen/AArch64/apply-terminal-rule.mir   | 98 +++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100644 llvm/test/CodeGen/AArch64/apply-terminal-rule.mir

diff --git a/llvm/test/CodeGen/AArch64/apply-terminal-rule.mir b/llvm/test/CodeGen/AArch64/apply-terminal-rule.mir
new file mode 100644
index 0000000000000..f59452d8f253d
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/apply-terminal-rule.mir
@@ -0,0 +1,98 @@
+# RUN: llc -mtriple=aarch64 -run-pass=register-coalescer -terminal-rule=1 -o - %s | FileCheck %s
+
+# Apply terminal rule for: %5
+--- |
+  @A = external dso_local global [100 x i32], align 4
+  
+  define i32 @test(i32 %n) {
+  entry:
+    %cmp63 = icmp sgt i32 %n, 0
+    br i1 %cmp63, label %for.body.preheader, label %for.cond.cleanup
+  
+  for.body.preheader:                               ; preds = %entry
+    %0 = load i32, i32* getelementptr inbounds ([100 x i32], [100 x i32]* @A, i64 0, i64 0), align 4
+    br label %for.body
+  
+  for.cond.cleanup:                                 ; preds = %for.body, %entry
+    %sum.0.lcssa = phi i32 [ %n, %entry ], [ %div, %for.body ]
+    ret i32 %sum.0.lcssa
+  
+  for.body:                                         ; preds = %for.body, %for.body.preheader
+    %lsr.iv = phi i32 [ %n, %for.body.preheader ], [ %lsr.iv.next, %for.body ]
+    %sum.065 = phi i32 [ %div, %for.body ], [ %n, %for.body.preheader ]
+    %call = tail call i32 @_Z3usei(i32 %0)
+    %div = sdiv i32 %sum.065, %call
+    %lsr.iv.next = add i32 %lsr.iv, -1
+    %exitcond.not = icmp eq i32 %lsr.iv.next, 0
+    br i1 %exitcond.not, label %for.cond.cleanup, label %for.body
+  }
+  
+  declare i32 @_Z3usei(i32)
+
+...
+---
+name:            test
+alignment:       4
+tracksRegLiveness: true
+liveins:
+  - { reg: '$w0', virtual-reg: '%6' }
+frameInfo:
+  maxAlignment:    1
+  adjustsStack:    true
+  hasCalls:        true
+  maxCallFrameSize: 0
+machineFunctionInfo: {}
+body:             |
+  bb.0.entry:
+    successors: %bb.1(0x50000000), %bb.4(0x30000000)
+    liveins: $w0
+
+    %0:gpr32common = COPY $w0
+    dead $wzr = SUBSWri %0:gpr32common, 1, 0, implicit-def $nzcv
+    Bcc 10, %bb.1, implicit killed $nzcv
+    B %bb.4
+
+  bb.1.for.body.preheader:
+    successors: %bb.3(0x80000000)
+
+    %1:gpr64common = ADRP target-flags(aarch64-page) @A
+    %2:gpr32 = LDRWui %1:gpr64common, target-flags(aarch64-pageoff, aarch64-nc) @A :: (dereferenceable load (s32) from `i32* getelementptr inbounds ([100 x i32], [100 x i32]* @A, i64 0, i64 0)`)
+    %3:gpr32all = COPY %2:gpr32
+    %4:gpr32sp = COPY %0:gpr32common
+    %5:gpr32 = COPY %0:gpr32common
+    B %bb.3
+
+  bb.2.for.cond.cleanup:
+    %6:gpr32all = COPY %7:gpr32all
+    $w0 = COPY %6:gpr32all
+    RET_ReallyLR implicit $w0
+
+  bb.3.for.body:
+    successors: %bb.2(0x04000000), %bb.3(0x7c000000)
+    
+    %8:gpr32 = COPY %5:gpr32
+    %9:gpr32sp = COPY %4:gpr32sp
+    ADJCALLSTACKDOWN 0, 0, implicit-def dead $sp, implicit $sp
+    $w0 = COPY %3:gpr32all
+    BL @_Z3usei, csr_aarch64_aapcs, implicit-def dead $lr, implicit $sp,implicit killed $w0, implicit-def $sp, implicit-def $w0
+    ADJCALLSTACKUP 0, 0, implicit-def dead $sp, implicit $sp
+    %10:gpr32 = COPY $w0
+    %11:gpr32 = SDIVWr %8:gpr32, %10:gpr32
+    %12:gpr32all = COPY %11:gpr32
+    %13:gpr32 = SUBSWri %9:gpr32sp, 1, 0, implicit-def $nzcv
+    %14:gpr32all = COPY %13:gpr32
+    %7:gpr32all = COPY %12:gpr32all
+    %4:gpr32sp = COPY %14:gpr32all
+    %5:gpr32 = COPY %12:gpr32all
+    Bcc 0, %bb.2, implicit killed $nzcv
+    B %bb.3
+
+  bb.4:
+  ; CHECK-LABEL: bb.4:
+  ; CHECK-NOT: %6:gpr32 = COPY %5
+    successors: %bb.2(0x80000000)
+
+    %7:gpr32all = COPY %0:gpr32common
+    B %bb.2
+
+...