[llvm] [StackColoring] Add test for stack-coloring and setjmp (PR #199959)

[Evgenii Kudriashov via llvm-commits]

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@@ -0,0 +1,76 @@
+; RUN: llc -mtriple=x86_64-linux -no-stack-coloring=false -debug-only=stack-coloring < %s -o /dev/null 2>&1 | FileCheck %s
+; REQUIRES: asserts
+
+; Test that volatile stack slots accessed after setjmp are not merged.
+; Volatile variables must retain their values across longjmp, so their
+; stack slots cannot be reused even if their lifetimes don't overlap.
+
+declare i32 @setjmp(ptr) returns_twice
+declare void @baz(ptr)
+declare void @llvm.lifetime.start.p0(ptr nocapture)
+declare void @llvm.lifetime.end.p0(ptr nocapture)
+declare dso_local void @stash(ptr noundef, ptr noundef) local_unnamed_addr 
+declare dso_local void @use(ptr noundef) local_unnamed_addr 
+
+; CHECK-LABEL: setjmp_test
+; CHECK: Conservative slots : { 1 1 }
+; CHECK: Merge 0 slots
+
+define void @setjmp_test(ptr %jump_buffer) {
+entry:
+  %foo = alloca i32, align 4
+  %bar = alloca [100 x i32], align 4
+
+  call void @llvm.lifetime.start.p0(ptr %foo)
+  call void @llvm.lifetime.start.p0(ptr %bar)
+
+  %setjmp_result = call i32 @setjmp(ptr %jump_buffer)
+  %cmp = icmp eq i32 %setjmp_result, 0
+  br i1 %cmp, label %after_setjmp, label %continue
+
+after_setjmp:
+  store volatile i32 100, ptr %foo, align 4
+  br label %exit
+
+continue:
+  store i32 100, ptr %bar, align 4
+  call void @baz(ptr %bar)
+  call void @llvm.lifetime.end.p0(ptr %foo)
+  call void @llvm.lifetime.end.p0(ptr %bar)
+  br label %exit
+
+exit:
+  ret void
+}
+
+; CHECK-LABEL: setjmp_test_2
+; CHECK: Conservative slots : { 1 1 }
+; CHECK: Merge 0 slots
+
+
+%struct.T = type { [100 x i32] }
+
+define dso_local void @setjmp_test_2(ptr %jump_buffer) local_unnamed_addr  {
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e-kud wrote:

Is it a scenario when `test1` must be alive in both paths and thus cannot be merged? Maybe add a user in `if.end` to be more explicit and a comment. Because the first comment describes only volatile use-case. This one looks differently.

https://github.com/llvm/llvm-project/pull/199959