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[InstCombine] Add test for missing (or (zext x), (shl (ashr x, bw-1))) -> (sext x) case

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#129363 handled all the cases where there was a sext for the original source value, but not for cases where the source is already half the size of the destination type

Another regression noticed in #76524
This commit is contained in:
Simon Pilgrim 2025-03-07 17:38:21 +00:00
parent afbbca5c9d
commit 445c43d712
1 changed files with 25 additions and 0 deletions
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25
llvm/test/Transforms/InstCombine/iX-ext-split.ll
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@ -89,6 +89,31 @@ entry:
ret void
}
; (non)ext split from i64 to i128
define void @i128_ext_split_store_i64(i64 %x, ptr %out) {
; CHECK-LABEL: define void @i128_ext_split_store_i64(
; CHECK-SAME: i64 [[X:%.*]], ptr [[OUT:%.*]]) {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: [[LO:%.*]] = zext i64 [[X]] to i128
; CHECK-NEXT: [[SIGN:%.*]] = ashr i64 [[X]], 63
; CHECK-NEXT: [[WIDEN:%.*]] = zext i64 [[SIGN]] to i128
; CHECK-NEXT: [[HI:%.*]] = shl nuw i128 [[WIDEN]], 64
; CHECK-NEXT: [[RES:%.*]] = or disjoint i128 [[HI]], [[LO]]
; CHECK-NEXT: store i128 [[RES]], ptr [[OUT]], align 16
; CHECK-NEXT: ret void
;
entry:
%lo = zext i64 %x to i128
%sign = ashr i64 %x, 63
%widen = zext i64 %sign to i128
%hi = shl nuw i128 %widen, 64
%res = or disjoint i128 %hi, %lo
store i128 %res, ptr %out, align 16
ret void
}
; negative test - wrong constant value
define i128 @i128_ext_split_neg1(i32 %x) {
; CHECK-LABEL: define i128 @i128_ext_split_neg1(