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6cacbbe0b7
As with other transforms in demanded bits, we must be careful not to wrongly propagate nsw/nuw if we are reducing values leading up to the shift. This bug was introduced with 1b24f35f843c and leads to the miscompile shown in: https://llvm.org/PR50341
101 lines
2.9 KiB
LLVM
101 lines
2.9 KiB
LLVM
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
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; RUN: opt -instcombine -S < %s | FileCheck %s
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define i16 @sext_shl_trunc_same_size(i16 %x, i32 %y) {
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; CHECK-LABEL: @sext_shl_trunc_same_size(
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; CHECK-NEXT: [[CONV1:%.*]] = zext i16 [[X:%.*]] to i32
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; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[CONV1]], [[Y:%.*]]
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; CHECK-NEXT: [[T:%.*]] = trunc i32 [[SHL]] to i16
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; CHECK-NEXT: ret i16 [[T]]
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;
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%conv = sext i16 %x to i32
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%shl = shl i32 %conv, %y
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%t = trunc i32 %shl to i16
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ret i16 %t
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}
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define i5 @sext_shl_trunc_smaller(i16 %x, i32 %y) {
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; CHECK-LABEL: @sext_shl_trunc_smaller(
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; CHECK-NEXT: [[CONV1:%.*]] = zext i16 [[X:%.*]] to i32
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; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[CONV1]], [[Y:%.*]]
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; CHECK-NEXT: [[T:%.*]] = trunc i32 [[SHL]] to i5
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; CHECK-NEXT: ret i5 [[T]]
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;
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%conv = sext i16 %x to i32
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%shl = shl i32 %conv, %y
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%t = trunc i32 %shl to i5
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ret i5 %t
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}
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; negative test - demanding 1 high-bit too many to change the extend
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define i17 @sext_shl_trunc_larger(i16 %x, i32 %y) {
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; CHECK-LABEL: @sext_shl_trunc_larger(
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; CHECK-NEXT: [[CONV:%.*]] = sext i16 [[X:%.*]] to i32
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; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[CONV]], [[Y:%.*]]
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; CHECK-NEXT: [[T:%.*]] = trunc i32 [[SHL]] to i17
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; CHECK-NEXT: ret i17 [[T]]
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;
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%conv = sext i16 %x to i32
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%shl = shl i32 %conv, %y
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%t = trunc i32 %shl to i17
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ret i17 %t
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}
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define i32 @sext_shl_mask(i16 %x, i32 %y) {
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; CHECK-LABEL: @sext_shl_mask(
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; CHECK-NEXT: [[CONV1:%.*]] = zext i16 [[X:%.*]] to i32
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; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[CONV1]], [[Y:%.*]]
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; CHECK-NEXT: [[T:%.*]] = and i32 [[SHL]], 65535
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; CHECK-NEXT: ret i32 [[T]]
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;
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%conv = sext i16 %x to i32
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%shl = shl i32 %conv, %y
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%t = and i32 %shl, 65535
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ret i32 %t
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}
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; negative test - demanding a bit that could change with sext
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define i32 @sext_shl_mask_higher(i16 %x, i32 %y) {
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; CHECK-LABEL: @sext_shl_mask_higher(
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; CHECK-NEXT: [[CONV:%.*]] = sext i16 [[X:%.*]] to i32
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; CHECK-NEXT: [[SHL:%.*]] = shl i32 [[CONV]], [[Y:%.*]]
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; CHECK-NEXT: [[T:%.*]] = and i32 [[SHL]], 65536
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; CHECK-NEXT: ret i32 [[T]]
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;
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%conv = sext i16 %x to i32
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%shl = shl i32 %conv, %y
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%t = and i32 %shl, 65536
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ret i32 %t
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}
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; May need some, but not all of the bits set by the 'or'.
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define i32 @set_shl_mask(i32 %x, i32 %y) {
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; CHECK-LABEL: @set_shl_mask(
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; CHECK-NEXT: [[Z:%.*]] = or i32 [[X:%.*]], 65537
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; CHECK-NEXT: [[S:%.*]] = shl i32 [[Z]], [[Y:%.*]]
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; CHECK-NEXT: [[R:%.*]] = and i32 [[S]], 65536
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; CHECK-NEXT: ret i32 [[R]]
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;
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%z = or i32 %x, 196609
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%s = shl i32 %z, %y
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%r = and i32 %s, 65536
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ret i32 %r
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}
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; PR50341
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define i8 @must_drop_poison(i32 %x, i32 %y) {
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; CHECK-LABEL: @must_drop_poison(
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; CHECK-NEXT: [[S:%.*]] = shl i32 [[X:%.*]], [[Y:%.*]]
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; CHECK-NEXT: [[T:%.*]] = trunc i32 [[S]] to i8
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; CHECK-NEXT: ret i8 [[T]]
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;
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%a = and i32 %x, 255
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%s = shl nuw nsw i32 %a, %y
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%t = trunc i32 %s to i8
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ret i8 %t
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}
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