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llvm-reduce: Change function return types if function is not called #134035

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d65f9ca
llvm-reduce: Change function return types if function is not called
arsenm Apr 2, 2025
8221f36
Fix multiple return case
arsenm Apr 2, 2025
b98c505
Fix return attributes
arsenm Apr 2, 2025
254c039
Fix returned attr
arsenm Apr 2, 2025
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Fix multiple return case
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@arsenm
arsenm committed Apr 25, 2025
commit 8221f36c240e4d4f12e67a8f452ce4aa96364027
41 changes: 35 additions & 6 deletions llvm/test/tools/llvm-reduce/reduce-values-to-return-new-return-type.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -21,20 +21,49 @@ define i64 @inst_to_return_has_different_type_but_no_func_call_use(ptr %arg) {
ret i64 0
}

; INTERESTING-LABEL: @callsite_different_type_unused_0(
; RESULT-LABEL: define i64 @inst_to_return_has_different_type_but_call_result_unused(
; RESULT-NEXT: %load = load i32, ptr %arg
; RESULT-NEXT: store i32 %load, ptr @gv
; RESULT-NEXT: ret i64 0
; INTERESTING-LABEL: @multiple_returns_wrong_return_type_no_callers(
; RESULT-LABEL: define i32 @multiple_returns_wrong_return_type_no_callers(

; RESULT: bb0:
; RESULT-NEXT: %load0 = load i32,
; RESULT-NEXT: ret i32 %load0

; RESULT: bb1:
; RESULT-NEXT: store i32 8, ptr null
; RESULT-NEXT: ret i32 0
define i64 @multiple_returns_wrong_return_type_no_callers(ptr %arg, i1 %cond, i64 %arg2) {
entry:
br i1 %cond, label %bb0, label %bb1

bb0:
%load0 = load i32, ptr %arg
store i32 %load0, ptr @gv
ret i64 234

bb1:
store i32 8, ptr null
ret i64 %arg2

bb2:
ret i64 34
}

; INTERESTING-LABEL: define {{.+}} @callsite_different_type_unused_0(

; RESULT-LABEL: define i64 @callsite_different_type_unused_0(ptr %arg) {
; RESULT-NEXT: %unused0 = call i64 @inst_to_return_has_different_type_but_call_result_unused(ptr %arg)
; RESULT-NEXT: ret i64 %unused0
define void @callsite_different_type_unused_0(ptr %arg) {
%unused0 = call i64 @inst_to_return_has_different_type_but_call_result_unused(ptr %arg)
%unused1 = call i64 @inst_to_return_has_different_type_but_call_result_unused(ptr null)
ret void
}

; TODO: Could rewrite this return from i64 to i32 since the callsite is unused.
; INTERESTING-LABEL: @inst_to_return_has_different_type_but_call_result_unused(
; INTERESTING-LABEL: define {{.+}} @inst_to_return_has_different_type_but_call_result_unused(
; RESULT-LABEL: define i64 @inst_to_return_has_different_type_but_call_result_unused(
; RESULT-NEXT: %load = load i32, ptr %arg
; RESULT-NEXT: store i32 %load, ptr @gv
; RESULT: ret i64 0
define i64 @inst_to_return_has_different_type_but_call_result_unused(ptr %arg) {
%load = load i32, ptr %arg
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2 changes: 1 addition & 1 deletion llvm/tools/llvm-reduce/deltas/ReduceValuesToReturn.cpp
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Expand Up @@ -56,7 +56,7 @@ static void rewriteFuncWithReturnType(Function &OldF, Value *NewRetValue) {
NewRetI ? NewRetI->getIterator() : EntryBB.end();

// Hack up any return values in other blocks, we can't leave them as ret void.
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Comment needs updating?

Suggested change
// Hack up any return values in other blocks, we can't leave them as ret void.
// Hack up any return values in other blocks, we can't leave them as returning OldRetTy.

if (OldFuncTy->getReturnType()->isVoidTy()) {
if (OldFuncTy->getReturnType() != NewRetTy) {
for (BasicBlock &OtherRetBB : OldF) {
if (&OtherRetBB != NewRetBlock) {
auto *OrigRI = dyn_cast<ReturnInst>(OtherRetBB.getTerminator());
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