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7 changes: 4 additions & 3 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
Original file line number Diff line number Diff line change
Expand Up @@ -2441,9 +2441,10 @@ Instruction *InstCombinerImpl::foldICmpShlConstant(ICmpInst &Cmp,
Type *TruncTy = ShType->getWithNewBitWidth(TypeBits - Amt);
Constant *NewC =
ConstantInt::get(TruncTy, RHSC.ashr(*ShiftAmt).trunc(TypeBits - Amt));
return new ICmpInst(
CmpPred, Builder.CreateTrunc(X, TruncTy, "", Shl->hasNoSignedWrap()),
NewC);
return new ICmpInst(CmpPred,
Builder.CreateTrunc(X, TruncTy, "", /*IsNUW=*/false,
Shl->hasNoSignedWrap()),
NewC);
}
}

Expand Down
31 changes: 31 additions & 0 deletions llvm/test/Transforms/InstCombine/icmp.ll
Original file line number Diff line number Diff line change
Expand Up @@ -5255,6 +5255,16 @@ define i1 @test_icmp_shl_nuw(i64 %x) {
ret i1 %cmp
}

define i1 @test_icmp_shl_nuw_i31(i31 %x) {
; CHECK-LABEL: @test_icmp_shl_nuw_i31(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i31 [[X:%.*]], 250
; CHECK-NEXT: ret i1 [[CMP]]
;
%shl = shl nuw i31 %x, 23
%cmp = icmp ugt i31 %shl, -50331648
ret i1 %cmp
}

define i1 @test_icmp_shl_nsw(i64 %x) {
; CHECK-LABEL: @test_icmp_shl_nsw(
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[X:%.*]], 3
Expand All @@ -5265,6 +5275,17 @@ define i1 @test_icmp_shl_nsw(i64 %x) {
ret i1 %cmp
}

define i1 @test_icmp_shl_nsw_i31(i31 %x) {
; CHECK-LABEL: @test_icmp_shl_nsw_i31(
; CHECK-NEXT: [[TMP1:%.*]] = trunc nsw i31 [[X:%.*]] to i8
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i8 [[TMP1]], -6
; CHECK-NEXT: ret i1 [[CMP]]
;
%shl = shl nsw i31 %x, 23
%cmp = icmp ugt i31 %shl, -50331648
ret i1 %cmp
}

define <2 x i1> @test_icmp_shl_vec(<2 x i64> %x) {
; CHECK-LABEL: @test_icmp_shl_vec(
; CHECK-NEXT: [[TMP1:%.*]] = trunc <2 x i64> [[X:%.*]] to <2 x i32>
Expand Down Expand Up @@ -5295,3 +5316,13 @@ define i1 @test_icmp_shl_sgt(i64 %x) {
%cmp = icmp sgt i64 %shl, 8589934591
ret i1 %cmp
}

define i1 @pr94897(i32 range(i32 -2147483648, 0) %x) {
; CHECK-LABEL: @pr94897(
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i32 [[X:%.*]], -3
; CHECK-NEXT: ret i1 [[CMP]]
;
%shl = shl nsw i32 %x, 24
%cmp = icmp ugt i32 %shl, -50331648
ret i1 %cmp
}