[llvm] [CodeGen] Generalize trap emission after SP check fail (PR #109744)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,36 @@
+; NOTE: Do not autogenerate, we'd lose the .Lfunc_end0 -NEXT checks otherwise.
+;; Make sure we emit trap instructions after stack protector checks iff NoTrapAfterNoReturn is false.
+
+; RUN: llc -mtriple=aarch64 -fast-isel=false -global-isel=false -verify-machineinstrs \
+; RUN:     -trap-unreachable=false -o - %s | FileCheck --check-prefix=NO_TRAP_UNREACHABLE %s
+; RUN: llc -mtriple=aarch64 -fast-isel=false -global-isel=false -verify-machineinstrs \
+; RUN:     -trap-unreachable -no-trap-after-noreturn -o - %s | FileCheck --check-prefix=NO_TRAP_UNREACHABLE %s
+; RUN: llc -mtriple=aarch64 -fast-isel=false -global-isel=false -verify-machineinstrs \
+; RUN:     -trap-unreachable -no-trap-after-noreturn=false -o - %s | FileCheck --check-prefix=TRAP_UNREACHABLE %s
+
+;; Make sure FastISel doesn't break anything.
+; RUN: llc -mtriple=aarch64 -fast-isel -verify-machineinstrs \
+; RUN:     -trap-unreachable=false -o - %s | FileCheck --check-prefix=NO_TRAP_UNREACHABLE %s
+; RUN: llc -mtriple=aarch64 -fast-isel -verify-machineinstrs \
+; RUN:     -trap-unreachable -no-trap-after-noreturn -o - %s | FileCheck --check-prefix=NO_TRAP_UNREACHABLE %s
+; RUN: llc -mtriple=aarch64 -fast-isel -verify-machineinstrs \
+; RUN:     -trap-unreachable -no-trap-after-noreturn=false -o - %s | FileCheck --check-prefix=TRAP_UNREACHABLE %s
+
+define void @test() nounwind ssp {
+; NO_TRAP_UNREACHABLE-LABEL: test:
+; NO_TRAP_UNREACHABLE:         bl __stack_chk_fail
+; NO_TRAP_UNREACHABLE-NOT:     brk #0x1
+; NO_TRAP_UNREACHABLE-NEXT:  .Lfunc_end0
+;
+; TRAP_UNREACHABLE-LABEL: test:
+; TRAP_UNREACHABLE:         bl __stack_chk_fail
+; TRAP_UNREACHABLE-NEXT:    brk #0x1
+; TRAP_UNREACHABLE-NEXT:  .Lfunc_end0
+
+entry:
+  %buf = alloca [8 x i8]
+  %2 = call i32(ptr) @callee(ptr %buf) nounwind
----------------
arsenm wrote:

```suggestion
  %result = call i32(ptr) @callee(ptr %buf) nounwind
```

https://github.com/llvm/llvm-project/pull/109744