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[ConstraintElim] Decompose sub nsw (#118219)
Closes #118211.
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‎llvm/lib/Transforms/Scalar/ConstraintElimination.cpp

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Original file line numberDiff line numberDiff line change
@@ -527,6 +527,13 @@ static Decomposition decompose(Value *V,
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if (match(V, m_NSWAdd(m_Value(Op0), m_Value(Op1))))
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return MergeResults(Op0, Op1, IsSigned);
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if (match(V, m_NSWSub(m_Value(Op0), m_Value(Op1)))) {
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auto ResA = decompose(Op0, Preconditions, IsSigned, DL);
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auto ResB = decompose(Op1, Preconditions, IsSigned, DL);
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ResA.sub(ResB);
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return ResA;
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}
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ConstantInt *CI;
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if (match(V, m_NSWMul(m_Value(Op0), m_ConstantInt(CI))) && canUseSExt(CI)) {
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auto Result = decompose(Op0, Preconditions, IsSigned, DL);

‎llvm/test/Transforms/ConstraintElimination/sub-nsw.ll

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@@ -0,0 +1,129 @@
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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; RUN: opt -passes=constraint-elimination -S %s | FileCheck %s
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define i1 @test_decompose_sub_nsw_sgt_nonneg(i32 %x, i32 %y) {
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; CHECK-LABEL: define i1 @test_decompose_sub_nsw_sgt_nonneg(
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; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 [[Y]], [[X]]
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; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SUB]], 10
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; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
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; CHECK: [[IF_THEN]]:
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; CHECK-NEXT: ret i1 true
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; CHECK: [[IF_ELSE]]:
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; CHECK-NEXT: ret i1 true
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;
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entry:
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%sub = sub nsw i32 %y, %x
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%cond = icmp sgt i32 %sub, 10
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br i1 %cond, label %if.then, label %if.else
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if.then:
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%ret = icmp slt i32 %x, %y
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ret i1 %ret
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if.else:
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ret i1 true
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}
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define i1 @test_decompose_sub_nsw_sgt_zero(i32 %x, i32 %y) {
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; CHECK-LABEL: define i1 @test_decompose_sub_nsw_sgt_zero(
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; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 [[Y]], [[X]]
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; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SUB]], 0
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; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
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; CHECK: [[IF_THEN]]:
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; CHECK-NEXT: ret i1 true
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; CHECK: [[IF_ELSE]]:
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; CHECK-NEXT: ret i1 true
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;
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entry:
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%sub = sub nsw i32 %y, %x
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%cond = icmp sgt i32 %sub, 0
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br i1 %cond, label %if.then, label %if.else
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if.then:
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%ret = icmp slt i32 %x, %y
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ret i1 %ret
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if.else:
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ret i1 true
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}
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define i1 @test_decompose_sub_nsw_sgt_zero_inv(i32 %x, i32 %y) {
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; CHECK-LABEL: define i1 @test_decompose_sub_nsw_sgt_zero_inv(
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; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 [[Y]], [[X]]
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; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SUB]], 10
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; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
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; CHECK: [[IF_THEN]]:
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; CHECK-NEXT: ret i1 false
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; CHECK: [[IF_ELSE]]:
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; CHECK-NEXT: ret i1 true
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;
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entry:
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%sub = sub nsw i32 %y, %x
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%cond = icmp sgt i32 %sub, 10
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br i1 %cond, label %if.then, label %if.else
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if.then:
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%ret = icmp sge i32 %x, %y
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ret i1 %ret
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if.else:
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ret i1 true
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}
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define i1 @test_decompose_sub_nonsw_sgt_zero(i32 %x, i32 %y) {
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; CHECK-LABEL: define i1 @test_decompose_sub_nonsw_sgt_zero(
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; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: [[SUB:%.*]] = sub i32 [[Y]], [[X]]
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; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SUB]], 10
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; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
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; CHECK: [[IF_THEN]]:
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; CHECK-NEXT: [[RET:%.*]] = icmp slt i32 [[X]], [[Y]]
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; CHECK-NEXT: ret i1 [[RET]]
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; CHECK: [[IF_ELSE]]:
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; CHECK-NEXT: ret i1 true
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;
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entry:
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%sub = sub i32 %y, %x
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%cond = icmp sgt i32 %sub, 10
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br i1 %cond, label %if.then, label %if.else
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if.then:
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%ret = icmp slt i32 %x, %y
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ret i1 %ret
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if.else:
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ret i1 true
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}
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define i1 @test_decompose_sub_nsw_sgt_neg(i32 %x, i32 %y) {
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; CHECK-LABEL: define i1 @test_decompose_sub_nsw_sgt_neg(
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; CHECK-SAME: i32 [[X:%.*]], i32 [[Y:%.*]]) {
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; CHECK-NEXT: [[ENTRY:.*:]]
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; CHECK-NEXT: [[SUB:%.*]] = sub nsw i32 [[Y]], [[X]]
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; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[SUB]], -10
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; CHECK-NEXT: br i1 [[COND]], label %[[IF_THEN:.*]], label %[[IF_ELSE:.*]]
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; CHECK: [[IF_THEN]]:
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; CHECK-NEXT: [[RET:%.*]] = icmp slt i32 [[X]], [[Y]]
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; CHECK-NEXT: ret i1 [[RET]]
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; CHECK: [[IF_ELSE]]:
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; CHECK-NEXT: ret i1 true
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;
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entry:
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%sub = sub nsw i32 %y, %x
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%cond = icmp sgt i32 %sub, -10
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br i1 %cond, label %if.then, label %if.else
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if.then:
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%ret = icmp slt i32 %x, %y
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ret i1 %ret
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if.else:
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ret i1 true
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}

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