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[InstCombine] Set samesign when converting signed predicates into unsigned #112642

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Merged
merged 3 commits into from
Oct 17, 2024
Merged

[InstCombine] Set samesign when converting signed predicates into unsigned #112642

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[InstCombine] Set `samesign` when converting signed predicates into u…
dtcxzyw Oct 17, 2024
961abf9
[InstCombine] Set `samesign` for unsigned predicates
dtcxzyw Oct 17, 2024
bd7ac7f
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dtcxzyw Oct 17, 2024
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7 changes: 5 additions & 2 deletions llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
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Expand Up @@ -6774,8 +6774,11 @@ Instruction *InstCombinerImpl::foldICmpUsingKnownBits(ICmpInst &I) {
// have the same sign.
if (I.isSigned() &&
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@nikic nikic Oct 17, 2024

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Shouldn't we also set the flag if !isSigned()?

((Op0Known.Zero.isNegative() && Op1Known.Zero.isNegative()) ||
(Op0Known.One.isNegative() && Op1Known.One.isNegative())))
return new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
(Op0Known.One.isNegative() && Op1Known.One.isNegative()))) {
ICmpInst *NewICmp = new ICmpInst(I.getUnsignedPredicate(), Op0, Op1);
NewICmp->setSameSign();
return NewICmp;
}

return nullptr;
}
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2 changes: 1 addition & 1 deletion llvm/test/Transforms/InstCombine/call-guard.ll
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Expand Up @@ -43,7 +43,7 @@ define void @test_guard_adjacent_diff_cond2(i32 %V1, i32 %V2) {
; CHECK-NEXT: [[TMP1:%.*]] = and i32 [[V1:%.*]], [[V2:%.*]]
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i32 [[TMP1]], 0
; CHECK-NEXT: [[AND:%.*]] = and i32 [[V1]], 255
; CHECK-NEXT: [[C:%.*]] = icmp ult i32 [[AND]], 129
; CHECK-NEXT: [[C:%.*]] = icmp samesign ult i32 [[AND]], 129
; CHECK-NEXT: [[TMP3:%.*]] = and i1 [[TMP2]], [[C]]
; CHECK-NEXT: call void (i1, ...) @llvm.experimental.guard(i1 [[TMP3]], i32 123) [ "deopt"() ]
; CHECK-NEXT: ret void
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2 changes: 1 addition & 1 deletion llvm/test/Transforms/InstCombine/icmp.ll
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Expand Up @@ -1457,7 +1457,7 @@ define <2 x i1> @test67vecinverse(<2 x i32> %x) {
define i1 @test68(i32 %x) {
; CHECK-LABEL: @test68(
; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 127
; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i32 [[AND]], 30
; CHECK-NEXT: [[CMP:%.*]] = icmp samesign ugt i32 [[AND]], 30
; CHECK-NEXT: ret i1 [[CMP]]
;
%and = and i32 %x, 127
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2 changes: 1 addition & 1 deletion llvm/test/Transforms/InstCombine/indexed-gep-compares.ll
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Expand Up @@ -40,7 +40,7 @@ define ptr @test1_nuw(ptr %A, i32 %Offset) {
; CHECK: bb:
; CHECK-NEXT: [[RHS_IDX:%.*]] = phi i32 [ [[RHS_ADD:%.*]], [[BB]] ], [ [[TMP_IDX]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[RHS_ADD]] = add nuw nsw i32 [[RHS_IDX]], 4
; CHECK-NEXT: [[COND:%.*]] = icmp ugt i32 [[RHS_IDX]], 400
; CHECK-NEXT: [[COND:%.*]] = icmp samesign ugt i32 [[RHS_IDX]], 400
; CHECK-NEXT: br i1 [[COND]], label [[BB2:%.*]], label [[BB]]
; CHECK: bb2:
; CHECK-NEXT: [[RHS_PTR:%.*]] = getelementptr inbounds nuw i8, ptr [[A:%.*]], i32 [[RHS_IDX]]
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4 changes: 2 additions & 2 deletions llvm/test/Transforms/InstCombine/phi-known-bits-operand-order.ll
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Expand Up @@ -20,7 +20,7 @@ define void @phi_recurrence_start_first() {
; CHECK-NEXT: br i1 [[COND_V2]], label [[FOR_COND11:%.*]], label [[FOR_COND26]]
; CHECK: for.cond11:
; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[START]], [[IF_THEN]] ], [ [[STEP:%.*]], [[FOR_COND11]] ]
; CHECK-NEXT: [[CMP13:%.*]] = icmp ult i32 [[I_1]], 100
; CHECK-NEXT: [[CMP13:%.*]] = icmp samesign ult i32 [[I_1]], 100
; CHECK-NEXT: [[STEP]] = add nuw nsw i32 [[I_1]], 1
; CHECK-NEXT: br i1 [[CMP13]], label [[FOR_COND11]], label [[WHILE_END]]
; CHECK: for.cond26:
Expand Down Expand Up @@ -68,7 +68,7 @@ define void @phi_recurrence_step_first() {
; CHECK-NEXT: br i1 [[COND_V2]], label [[FOR_COND11:%.*]], label [[FOR_COND26]]
; CHECK: for.cond11:
; CHECK-NEXT: [[I_1:%.*]] = phi i32 [ [[STEP:%.*]], [[FOR_COND11]] ], [ [[START]], [[IF_THEN]] ]
; CHECK-NEXT: [[CMP13:%.*]] = icmp ult i32 [[I_1]], 100
; CHECK-NEXT: [[CMP13:%.*]] = icmp samesign ult i32 [[I_1]], 100
; CHECK-NEXT: [[STEP]] = add nuw nsw i32 [[I_1]], 1
; CHECK-NEXT: br i1 [[CMP13]], label [[FOR_COND11]], label [[WHILE_END]]
; CHECK: for.cond26:
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