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[InstCombine] Add test for freeze of PHI with noundef start value (NFC) #157112

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Merged
merged 3 commits into from
Sep 9, 2025
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[InstCombine] Add test for freeze of PHI with noundef start value (NFC) #157112

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[InstCombine] Add test for freeze of PHI with noundef start value (NFC)
c-rhodes Sep 5, 2025
41dfb5e
update label names
c-rhodes Sep 5, 2025
22337b8
update label names
c-rhodes Sep 5, 2025
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49 changes: 49 additions & 0 deletions llvm/test/Transforms/InstCombine/freeze.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -1135,6 +1135,55 @@ exit:
ret void
}

; We can remove this freeze as the incoming values to the PHI have the same
; well-defined start value and the GEP can't produce poison, but this is
; currently unsupported.
define void @fold_phi_noundef_start_value(ptr noundef %init, i1 %cond.0, i1 %cond.1, i1 %cond.2) {
; CHECK-LABEL: define void @fold_phi_noundef_start_value(
; CHECK-SAME: ptr noundef [[INIT:%.*]], i1 [[COND_0:%.*]], i1 [[COND_1:%.*]], i1 [[COND_2:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*]]:
; CHECK-NEXT: br label %[[LOOP:.*]]
; CHECK: [[LOOP]]:
; CHECK-NEXT: [[IV_0:%.*]] = phi ptr [ [[INIT]], %[[ENTRY]] ], [ [[IV_0_NEXT:%.*]], %[[LOOP_LATCH:.*]] ]
; CHECK-NEXT: br i1 [[COND_0]], label %[[LOOP_LATCH]], label %[[IF_ELSE:.*]]
; CHECK: [[IF_ELSE]]:
; CHECK-NEXT: [[IV_1:%.*]] = getelementptr i8, ptr [[IV_0]], i64 -8
; CHECK-NEXT: br label %[[LOOP_LATCH]]
; CHECK: [[LOOP_LATCH]]:
; CHECK-NEXT: [[IV_2:%.*]] = phi ptr [ [[IV_0]], %[[LOOP]] ], [ [[IV_1]], %[[IF_ELSE]] ]
; CHECK-NEXT: [[IV_2_FR:%.*]] = freeze ptr [[IV_2]]
; CHECK-NEXT: [[IV_2_FR_INT:%.*]] = ptrtoint ptr [[IV_2_FR]] to i64
; CHECK-NEXT: [[IV_0_INT:%.*]] = ptrtoint ptr [[IV_0]] to i64
; CHECK-NEXT: [[IDX:%.*]] = sub i64 [[IV_0_INT]], [[IV_2_FR_INT]]
; CHECK-NEXT: [[IV_0_NEXT]] = getelementptr i8, ptr [[IV_0]], i64 [[IDX]]
; CHECK-NEXT: br i1 [[COND_2]], label %[[EXIT:.*]], label %[[LOOP]]
; CHECK: [[EXIT]]:
; CHECK-NEXT: ret void
;
entry:
br label %loop

loop:
%iv.0 = phi ptr [ %init, %entry ], [ %iv.0.next, %loop.latch ]
br i1 %cond.0, label %loop.latch, label %if.else

if.else:
%iv.1 = getelementptr i8, ptr %iv.0, i64 -8
br label %loop.latch

loop.latch:
%iv.2 = phi ptr [ %iv.0, %loop ], [ %iv.1, %if.else ]
%iv.2.fr = freeze ptr %iv.2
%iv.2.fr.int = ptrtoint ptr %iv.2.fr to i64
%iv.0.int = ptrtoint ptr %iv.0 to i64
%idx = sub i64 %iv.0.int, %iv.2.fr.int
%iv.0.next = getelementptr i8, ptr %iv.0, i64 %idx
br i1 %cond.2, label %exit, label %loop

exit:
ret void
}

define void @fold_phi_invoke_start_value(i32 %n) personality ptr undef {
; CHECK-LABEL: define void @fold_phi_invoke_start_value(
; CHECK-SAME: i32 [[N:%.*]]) personality ptr undef {
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