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[DSE] Only consider provenance captures #138286

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Merged
merged 2 commits into from
May 5, 2025
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Merged

[DSE] Only consider provenance captures #138286

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0525581
[DSE] Add additional tests for escape analysis in DSE (NFC)
nikic May 2, 2025
21fc119
[DSE] Only consider provenance captures
nikic May 2, 2025
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6 changes: 4 additions & 2 deletions llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1213,7 +1213,8 @@ struct DSEState {

auto I = InvisibleToCallerAfterRet.insert({V, false});
if (I.second && isInvisibleToCallerOnUnwind(V) && isNoAliasCall(V))
I.first->second = !PointerMayBeCaptured(V, /*ReturnCaptures=*/true);
I.first->second = capturesNothing(PointerMayBeCaptured(
V, /*ReturnCaptures=*/true, CaptureComponents::Provenance));
return I.first->second;
}

Expand All @@ -1230,7 +1231,8 @@ struct DSEState {
// with the killing MemoryDef. But we refrain from doing so for now to
// limit compile-time and this does not cause any changes to the number
// of stores removed on a large test set in practice.
I.first->second = PointerMayBeCaptured(V, /*ReturnCaptures=*/false);
I.first->second = capturesAnything(PointerMayBeCaptured(
V, /*ReturnCaptures=*/false, CaptureComponents::Provenance));
return !I.first->second;
}

Expand Down
2 changes: 0 additions & 2 deletions llvm/test/Transforms/DeadStoreElimination/assume.ll
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Expand Up @@ -8,7 +8,6 @@ define void @f() {
; CHECK-NEXT: [[TMP1:%.*]] = call noalias ptr @_Znwm(i64 32)
; CHECK-NEXT: [[TMP2:%.*]] = icmp ugt ptr [[TMP1]], @global
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP2]])
; CHECK-NEXT: store i8 0, ptr [[TMP1]], align 1
; CHECK-NEXT: ret void
;
%tmp1 = call noalias ptr @_Znwm(i64 32)
Expand All @@ -23,7 +22,6 @@ define void @f2() {
; CHECK-NEXT: [[TMP1:%.*]] = call noalias ptr @_Znwm(i64 32)
; CHECK-NEXT: [[TMP2:%.*]] = icmp ugt ptr [[TMP1]], @global
; CHECK-NEXT: call void @llvm.assume(i1 [[TMP2]])
; CHECK-NEXT: store i8 0, ptr [[TMP1]], align 1
; CHECK-NEXT: call void @quux(ptr @global)
; CHECK-NEXT: ret void
;
Expand Down
54 changes: 53 additions & 1 deletion llvm/test/Transforms/DeadStoreElimination/simple.ll
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Expand Up @@ -304,6 +304,58 @@ define void @custom_malloc_no_escape() {
ret void
}

declare void @use.ptr(ptr)

define void @malloc_no_escape_via_attr() {
; CHECK-LABEL: @malloc_no_escape_via_attr(
; CHECK-NEXT: [[M:%.*]] = call ptr @malloc(i64 24)
; CHECK-NEXT: call void @use.ptr(ptr captures(none) [[M]])
; CHECK-NEXT: ret void
;
%m = call ptr @malloc(i64 24)
call void @use.ptr(ptr captures(none) %m)
store i8 0, ptr %m
ret void
}

define void @malloc_address_only_escape() {
; CHECK-LABEL: @malloc_address_only_escape(
; CHECK-NEXT: [[M:%.*]] = call ptr @malloc(i64 24)
; CHECK-NEXT: call void @use.ptr(ptr captures(address) [[M]])
; CHECK-NEXT: ret void
;
%m = call ptr @malloc(i64 24)
call void @use.ptr(ptr captures(address) %m)
store i8 0, ptr %m
ret void
}

define void @malloc_provenance_escape() {
; CHECK-LABEL: @malloc_provenance_escape(
; CHECK-NEXT: [[M:%.*]] = call ptr @malloc(i64 24)
; CHECK-NEXT: call void @use.ptr(ptr captures(provenance) [[M]])
; CHECK-NEXT: store i8 0, ptr [[M]], align 1
; CHECK-NEXT: ret void
;
%m = call ptr @malloc(i64 24)
call void @use.ptr(ptr captures(provenance) %m)
store i8 0, ptr %m
ret void
}

define void @malloc_read_provenance_escape() {
; CHECK-LABEL: @malloc_read_provenance_escape(
; CHECK-NEXT: [[M:%.*]] = call ptr @malloc(i64 24)
; CHECK-NEXT: call void @use.ptr(ptr captures(read_provenance) [[M]])
; CHECK-NEXT: store i8 0, ptr [[M]], align 1
; CHECK-NEXT: ret void
;
%m = call ptr @malloc(i64 24)
call void @use.ptr(ptr captures(read_provenance) %m)
store i8 0, ptr %m
ret void
}

define void @test21() {
; CHECK-LABEL: @test21(
; CHECK-NEXT: ret void
Expand Down Expand Up @@ -484,7 +536,7 @@ define i32 @test32(i1 %c, ptr %p, i32 %i, i1 %arg) {
; CHECK: bb1:
; CHECK-NEXT: store i32 [[V]], ptr [[P]], align 4
; CHECK-NEXT: call void @unknown_func()
; CHECK-NEXT: br i1 %arg, label [[BB1]], label [[BB2:%.*]]
; CHECK-NEXT: br i1 [[ARG:%.*]], label [[BB1]], label [[BB2:%.*]]
; CHECK: bb2:
; CHECK-NEXT: ret i32 0
;
Expand Down