================
@@ -1,33 +1,151 @@
-; RUN: llc < %s -asm-verbose=false -verify-machineinstrs | FileCheck %s
-; RUN: llc < %s -asm-verbose=false -fast-isel -fast-isel-abort=1
-verify-machineinstrs | FileCheck %s
+; The assertions in this file were autogenerated by
+; utils/update_llc_test_checks.py, but were hand-edited to add the
+; "end_function" lines to prevent the tests from passing when there
+; are superfluous instructions at the end of a function.
+; You can run update_llc_test_checks.py again, but please keep the
+; "end_function" lines intact when you commit.
-; Test that LLVM unreachable instruction and trap intrinsic are lowered to
-; wasm unreachable
+
+; --trap-unreachable and --no-trap-after-noreturn are sensitive and bug-prone
+; options for the WebAssembly back-end as, unlike in many other target
+; architechtures, unreachable code being compiled to a trap instruction (i.e.
+; WebAssembly "unreachable" instruction) is often necessary for the code to
+; pass wasm's validation step. We test that various combinations of
+; these options produce the expected output.
+; RUN: llc < %s -verify-machineinstrs | FileCheck %s
+; RUN: llc < %s -fast-isel -fast-isel-abort=1 -verify-machineinstrs |
FileCheck %s
+; RUN: llc < %s -verify-machineinstrs --trap-unreachable | FileCheck %s
+; RUN: llc < %s -fast-isel -fast-isel-abort=1 -verify-machineinstrs
--trap-unreachable | FileCheck %s
+; RUN: llc < %s -verify-machineinstrs --trap-unreachable
--no-trap-after-noreturn | FileCheck %s
+; RUN: llc < %s -fast-isel -fast-isel-abort=1 -verify-machineinstrs
--trap-unreachable --no-trap-after-noreturn | FileCheck %s
target triple = "wasm32-unknown-unknown"
-declare void @llvm.trap()
-declare void @llvm.debugtrap()
-declare void @abort()
-; CHECK-LABEL: f1:
-; CHECK: call abort{{$}}
-; CHECK: unreachable
-define i32 @f1() {
- call void @abort()
- unreachable
-}
+; Test that the LLVM trap and debug trap intrinsics are lowered to wasm
+; unreachable.
+
+declare void @llvm.trap() cold noreturn nounwind
+declare void @llvm.debugtrap() nounwind
-; CHECK-LABEL: f2:
-; CHECK: unreachable
-define void @f2() {
+define void @trap_ret_void() {
+; CHECK-LABEL: trap_ret_void:
+; CHECK: .functype trap_ret_void () -> ()
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: # fallthrough-return
+; CHECK-NEXT: end_function
call void @llvm.trap()
ret void
}
-; CHECK-LABEL: f3:
-; CHECK: unreachable
-define void @f3() {
+define void @debugtrap_ret_void() {
+; CHECK-LABEL: debugtrap_ret_void:
+; CHECK: .functype debugtrap_ret_void () -> ()
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: # fallthrough-return
+; CHECK-NEXT: end_function
call void @llvm.debugtrap()
ret void
}
+
+; LLVM trap followed by LLVM unreachable could become exactly one wasm
+; unreachable, but two are emitted currently.
+define void @trap_unreacheable() {
+; CHECK-LABEL: trap_unreacheable:
+; CHECK: .functype trap_unreacheable () -> ()
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: end_function
+ call void @llvm.trap()
+ unreachable
+}
+
+
+; Test that LLVM unreachable instruction is lowered to wasm unreachable when
+; necessary to fulfill the wasm operand stack requirements.
+
+declare void @ext_func()
+declare i32 @ext_func_i32()
+declare void @ext_never_return() noreturn
+
+; This test emits wasm unreachable to fill in for the missing i32 return value,
+; which is necessary for the function to pass wasm validation.
+define i32 @missing_ret_unreach() {
+; CHECK-LABEL: missing_ret_unreach:
+; CHECK: .functype missing_ret_unreach () -> (i32)
+; CHECK-NEXT: # %bb.0:
+; CHECK-NEXT: call ext_func
+; CHECK-NEXT: unreachable
+; CHECK-NEXT: end_function
+ call void @ext_func()
+ unreachable
+}
+
+; This is similar to the above test, but ensures wasm unreachable is emitted
+; even after a noreturn call.
----------------
aheejin wrote:
We can be more direct by saying that there is a LLVM optimization that omits
`unreachable` if that comes after a `noreturn` function, but because we always
set `--no-trap-after-noreturn` internally, we emit the `unreachable`.
https://github.com/llvm/llvm-project/pull/65876
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