[llvm] [MergeFunc] Remove discardables function before writing alias or thunk. (PR #128865)

[Florian Hahn via llvm-commits]

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@@ -43,14 +43,8 @@ define linkonce i32 @funA(i32 %x, i32 %y) {
 ; CHECK-NEXT:    ret i32 [[SUM3]]
 ;
 ;
-; CHECK-LABEL: define linkonce i32 @funC(
-; CHECK-SAME: i32 [[TMP0:%.*]], i32 [[TMP1:%.*]]) {
-; CHECK-NEXT:    [[TMP3:%.*]] = tail call i32 @[[GLOB0:[0-9]+]](i32 [[TMP0]], i32 [[TMP1]])
-; CHECK-NEXT:    ret i32 [[TMP3]]
-;
-;
 ; CHECK-LABEL: define linkonce i32 @funB(
 ; CHECK-SAME: i32 [[TMP0:%.*]], i32 [[TMP1:%.*]]) {
-; CHECK-NEXT:    [[TMP3:%.*]] = tail call i32 @[[GLOB0]](i32 [[TMP0]], i32 [[TMP1]])
+; CHECK-NEXT:    [[TMP3:%.*]] = tail call i32 @[[GLOB0:[0-9]+]](i32 [[TMP0]], i32 [[TMP1]])
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fhahn wrote:

Yep, the thunk that we introduce may also end up dead and could be cleaned up. I can also look into that separately?

> I was going to suggest that you add a check that funC no longer exists, but I see that even before this patch the test contains -implicit-check-not=funC - how was that working since there was a funC before?

I *think* the reason this worked before is that the check lines in the test were specifically checking for `funC`, disabling the implicit check not.

Added implicit-check-not for funA


https://github.com/llvm/llvm-project/pull/128865