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[InstCombine] Teach how to fold a select into a cttz/ctlz with the 'is_zero_undef' flag.
This patch teaches the Instruction Combiner how to fold a cttz/ctlz followed by a icmp plus select into a single cttz/ctlz with flag 'is_zero_undef' cleared. Added test InstCombine/select-cmp-cttz-ctlz.ll. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@227197 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrea Di Biagio
parent
0b2455c374
commit
944d86558e
@ -437,6 +437,66 @@ static Value *foldSelectICmpAndOr(const SelectInst &SI, Value *TrueVal,
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return Builder->CreateOr(V, Y);
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}
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/// Attempt to fold a cttz/ctlz followed by a icmp plus select into a single
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/// call to cttz/ctlz with flag 'is_zero_undef' cleared.
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///
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/// For example, we can fold the following code sequence:
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/// \code
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/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
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/// %1 = icmp ne i32 %x, 0
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/// %2 = select i1 %1, i32 %0, i32 32
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/// \code
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///
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/// into:
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/// %0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
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static Value *foldSelectCttzCtlz(ICmpInst *ICI, Value *TrueVal, Value *FalseVal,
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InstCombiner::BuilderTy *Builder) {
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ICmpInst::Predicate Pred = ICI->getPredicate();
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Value *CmpLHS = ICI->getOperand(0);
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Value *CmpRHS = ICI->getOperand(1);
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// Check if the condition value compares a value for equality against zero.
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if (!ICI->isEquality() || !match(CmpRHS, m_Zero()))
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return nullptr;
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Value *Count = FalseVal;
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Value *ValueOnZero = TrueVal;
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if (Pred == ICmpInst::ICMP_NE)
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std::swap(Count, ValueOnZero);
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// Skip zero extend/truncate.
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Value *V = nullptr;
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if (match(Count, m_ZExt(m_Value(V))) ||
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match(Count, m_Trunc(m_Value(V))))
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Count = V;
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// Check if the value propagated on zero is a constant number equal to the
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// sizeof in bits of 'Count'.
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unsigned SizeOfInBits = Count->getType()->getScalarSizeInBits();
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if (!match(ValueOnZero, m_SpecificInt(SizeOfInBits)))
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return nullptr;
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// Check that 'Count' is a call to intrinsic cttz/ctlz. Also check that the
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// input to the cttz/ctlz is used as LHS for the compare instruction.
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if (match(Count, m_Intrinsic<Intrinsic::cttz>(m_Specific(CmpLHS))) ||
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match(Count, m_Intrinsic<Intrinsic::ctlz>(m_Specific(CmpLHS)))) {
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IntrinsicInst *II = cast<IntrinsicInst>(Count);
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IRBuilder<> Builder(II);
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if (cast<ConstantInt>(II->getArgOperand(1))->isOne()) {
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// Explicitly clear the 'undef_on_zero' flag.
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IntrinsicInst *NewI = cast<IntrinsicInst>(II->clone());
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Type *Ty = NewI->getArgOperand(1)->getType();
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NewI->setArgOperand(1, Constant::getNullValue(Ty));
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Builder.Insert(NewI);
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Count = NewI;
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}
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return Builder.CreateZExtOrTrunc(Count, ValueOnZero->getType());
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}
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return nullptr;
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}
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/// visitSelectInstWithICmp - Visit a SelectInst that has an
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/// ICmpInst as its first operand.
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///
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@ -665,6 +725,9 @@ Instruction *InstCombiner::visitSelectInstWithICmp(SelectInst &SI,
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if (Value *V = foldSelectICmpAndOr(SI, TrueVal, FalseVal, Builder))
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return ReplaceInstUsesWith(SI, V);
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if (Value *V = foldSelectCttzCtlz(ICI, TrueVal, FalseVal, Builder))
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return ReplaceInstUsesWith(SI, V);
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return Changed ? &SI : nullptr;
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}
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@ -349,7 +349,8 @@ define i32 @ctlz_select(i32 %Value) nounwind {
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ret i32 %s
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; CHECK-LABEL: @ctlz_select(
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; CHECK: select i1 %tobool, i32 %ctlz, i32 32
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; CHECK-NEXT: call i32 @llvm.ctlz.i32(i32 %Value, i1 false)
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; CHECK-NEXT: ret i32
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}
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define i32 @cttz_select(i32 %Value) nounwind {
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@ -359,5 +360,6 @@ define i32 @cttz_select(i32 %Value) nounwind {
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ret i32 %s
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; CHECK-LABEL: @cttz_select(
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; CHECK: select i1 %tobool, i32 %cttz, i32 32
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; CHECK-NEXT: call i32 @llvm.cttz.i32(i32 %Value, i1 false)
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; CHECK-NEXT: ret i32
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}
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300
test/Transforms/InstCombine/select-cmp-cttz-ctlz.ll
Normal file
300
test/Transforms/InstCombine/select-cmp-cttz-ctlz.ll
Normal file
@ -0,0 +1,300 @@
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; RUN: opt -instcombine -S < %s | FileCheck %s
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; This test is to verify that the instruction combiner is able to fold
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; a cttz/ctlz followed by a icmp + select into a single cttz/ctlz with
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; the 'is_zero_undef' flag cleared.
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define i16 @test1(i16 %x) {
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; CHECK-LABEL: @test1(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i16 @llvm.ctlz.i16(i16 %x, i1 false)
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; CHECK-NEXT: ret i16 [[VAR]]
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entry:
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%0 = tail call i16 @llvm.ctlz.i16(i16 %x, i1 true)
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%tobool = icmp ne i16 %x, 0
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%cond = select i1 %tobool, i16 %0, i16 16
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ret i16 %cond
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}
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define i32 @test2(i32 %x) {
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; CHECK-LABEL: @test2(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i32 @llvm.ctlz.i32(i32 %x, i1 false)
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; CHECK-NEXT: ret i32 [[VAR]]
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entry:
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%0 = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
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%tobool = icmp ne i32 %x, 0
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%cond = select i1 %tobool, i32 %0, i32 32
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ret i32 %cond
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}
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define i64 @test3(i64 %x) {
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; CHECK-LABEL: @test3(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i64 @llvm.ctlz.i64(i64 %x, i1 false)
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; CHECK-NEXT: ret i64 [[VAR]]
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entry:
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%0 = tail call i64 @llvm.ctlz.i64(i64 %x, i1 true)
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%tobool = icmp ne i64 %x, 0
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%cond = select i1 %tobool, i64 %0, i64 64
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ret i64 %cond
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}
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define i16 @test4(i16 %x) {
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; CHECK-LABEL: @test4(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i16 @llvm.ctlz.i16(i16 %x, i1 false)
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; CHECK-NEXT: ret i16 [[VAR]]
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entry:
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%0 = tail call i16 @llvm.ctlz.i16(i16 %x, i1 true)
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%tobool = icmp eq i16 %x, 0
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%cond = select i1 %tobool, i16 16, i16 %0
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ret i16 %cond
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}
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define i32 @test5(i32 %x) {
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; CHECK-LABEL: @test5(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i32 @llvm.ctlz.i32(i32 %x, i1 false)
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; CHECK-NEXT: ret i32 [[VAR]]
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entry:
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%0 = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
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%tobool = icmp eq i32 %x, 0
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%cond = select i1 %tobool, i32 32, i32 %0
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ret i32 %cond
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}
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define i64 @test6(i64 %x) {
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; CHECK-LABEL: @test6(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i64 @llvm.ctlz.i64(i64 %x, i1 false)
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; CHECK-NEXT: ret i64 [[VAR]]
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entry:
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%0 = tail call i64 @llvm.ctlz.i64(i64 %x, i1 true)
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%tobool = icmp eq i64 %x, 0
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%cond = select i1 %tobool, i64 64, i64 %0
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ret i64 %cond
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}
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define i16 @test1b(i16 %x) {
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; CHECK-LABEL: @test1b(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i16 @llvm.cttz.i16(i16 %x, i1 false)
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; CHECK-NEXT: ret i16 [[VAR]]
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entry:
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%0 = tail call i16 @llvm.cttz.i16(i16 %x, i1 true)
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%tobool = icmp ne i16 %x, 0
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%cond = select i1 %tobool, i16 %0, i16 16
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ret i16 %cond
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}
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define i32 @test2b(i32 %x) {
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; CHECK-LABEL: @test2b(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
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; CHECK-NEXT: ret i32 [[VAR]]
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entry:
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%0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
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%tobool = icmp ne i32 %x, 0
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%cond = select i1 %tobool, i32 %0, i32 32
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ret i32 %cond
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}
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define i64 @test3b(i64 %x) {
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; CHECK-LABEL: @test3b(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i64 @llvm.cttz.i64(i64 %x, i1 false)
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; CHECK-NEXT: ret i64 [[VAR]]
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entry:
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%0 = tail call i64 @llvm.cttz.i64(i64 %x, i1 true)
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%tobool = icmp ne i64 %x, 0
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%cond = select i1 %tobool, i64 %0, i64 64
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ret i64 %cond
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}
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define i16 @test4b(i16 %x) {
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; CHECK-LABEL: @test4b(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i16 @llvm.cttz.i16(i16 %x, i1 false)
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; CHECK-NEXT: ret i16 [[VAR]]
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entry:
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%0 = tail call i16 @llvm.cttz.i16(i16 %x, i1 true)
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%tobool = icmp eq i16 %x, 0
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%cond = select i1 %tobool, i16 16, i16 %0
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ret i16 %cond
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}
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define i32 @test5b(i32 %x) {
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; CHECK-LABEL: @test5b(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
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; CHECK-NEXT: ret i32 [[VAR]]
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entry:
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%0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
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%tobool = icmp eq i32 %x, 0
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%cond = select i1 %tobool, i32 32, i32 %0
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ret i32 %cond
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}
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define i64 @test6b(i64 %x) {
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; CHECK-LABEL: @test6b(
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; CHECK: [[VAR:%[a-zA-Z0-9]+]] = tail call i64 @llvm.cttz.i64(i64 %x, i1 false)
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; CHECK-NEXT: ret i64 [[VAR]]
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entry:
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%0 = tail call i64 @llvm.cttz.i64(i64 %x, i1 true)
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%tobool = icmp eq i64 %x, 0
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%cond = select i1 %tobool, i64 64, i64 %0
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ret i64 %cond
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}
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define i32 @test1c(i16 %x) {
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; CHECK-LABEL: @test1c(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i16 @llvm.cttz.i16(i16 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = zext i16 [[VAR1]] to i32
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; CHECK-NEXT: ret i32 [[VAR2]]
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entry:
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%0 = tail call i16 @llvm.cttz.i16(i16 %x, i1 true)
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%cast2 = zext i16 %0 to i32
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%tobool = icmp ne i16 %x, 0
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%cond = select i1 %tobool, i32 %cast2, i32 16
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ret i32 %cond
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}
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define i64 @test2c(i16 %x) {
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; CHECK-LABEL: @test2c(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i16 @llvm.cttz.i16(i16 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = zext i16 [[VAR1]] to i64
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; CHECK-NEXT: ret i64 [[VAR2]]
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entry:
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%0 = tail call i16 @llvm.cttz.i16(i16 %x, i1 true)
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%conv = zext i16 %0 to i64
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%tobool = icmp ne i16 %x, 0
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%cond = select i1 %tobool, i64 %conv, i64 16
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ret i64 %cond
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}
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define i64 @test3c(i32 %x) {
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; CHECK-LABEL: @test3c(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = zext i32 [[VAR1]] to i64
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; CHECK-NEXT: ret i64 [[VAR2]]
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entry:
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%0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
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%conv = zext i32 %0 to i64
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%tobool = icmp ne i32 %x, 0
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%cond = select i1 %tobool, i64 %conv, i64 32
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ret i64 %cond
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}
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define i32 @test4c(i16 %x) {
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; CHECK-LABEL: @test4c(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i16 @llvm.ctlz.i16(i16 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = zext i16 [[VAR1]] to i32
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; CHECK-NEXT: ret i32 [[VAR2]]
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entry:
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%0 = tail call i16 @llvm.ctlz.i16(i16 %x, i1 true)
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%cast = zext i16 %0 to i32
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%tobool = icmp ne i16 %x, 0
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%cond = select i1 %tobool, i32 %cast, i32 16
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ret i32 %cond
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}
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define i64 @test5c(i16 %x) {
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; CHECK-LABEL: @test5c(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i16 @llvm.ctlz.i16(i16 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = zext i16 [[VAR1]] to i64
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; CHECK-NEXT: ret i64 [[VAR2]]
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entry:
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%0 = tail call i16 @llvm.ctlz.i16(i16 %x, i1 true)
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%cast = zext i16 %0 to i64
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%tobool = icmp ne i16 %x, 0
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%cond = select i1 %tobool, i64 %cast, i64 16
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ret i64 %cond
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}
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define i64 @test6c(i32 %x) {
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; CHECK-LABEL: @test6c(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i32 @llvm.ctlz.i32(i32 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = zext i32 [[VAR1]] to i64
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; CHECK-NEXT: ret i64 [[VAR2]]
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entry:
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%0 = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
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%cast = zext i32 %0 to i64
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%tobool = icmp ne i32 %x, 0
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%cond = select i1 %tobool, i64 %cast, i64 32
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ret i64 %cond
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}
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define i16 @test1d(i64 %x) {
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; CHECK-LABEL: @test1d(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i64 @llvm.cttz.i64(i64 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = trunc i64 [[VAR1]] to i16
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; CHECK-NEXT: ret i16 [[VAR2]]
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entry:
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%0 = tail call i64 @llvm.cttz.i64(i64 %x, i1 true)
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%conv = trunc i64 %0 to i16
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%tobool = icmp ne i64 %x, 0
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%cond = select i1 %tobool, i16 %conv, i16 64
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ret i16 %cond
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}
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define i32 @test2d(i64 %x) {
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; CHECK-LABEL: @test2d(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i64 @llvm.cttz.i64(i64 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = trunc i64 [[VAR1]] to i32
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; CHECK-NEXT: ret i32 [[VAR2]]
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entry:
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%0 = tail call i64 @llvm.cttz.i64(i64 %x, i1 true)
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%cast = trunc i64 %0 to i32
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%tobool = icmp ne i64 %x, 0
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%cond = select i1 %tobool, i32 %cast, i32 64
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ret i32 %cond
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}
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define i16 @test3d(i32 %x) {
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; CHECK-LABEL: @test3d(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i32 @llvm.cttz.i32(i32 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = trunc i32 [[VAR1]] to i16
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; CHECK-NEXT: ret i16 [[VAR2]]
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entry:
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%0 = tail call i32 @llvm.cttz.i32(i32 %x, i1 true)
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%cast = trunc i32 %0 to i16
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%tobool = icmp ne i32 %x, 0
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%cond = select i1 %tobool, i16 %cast, i16 32
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ret i16 %cond
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}
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define i16 @test4d(i64 %x) {
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; CHECK-LABEL: @test4d(
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; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i64 @llvm.ctlz.i64(i64 %x, i1 false)
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; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = trunc i64 [[VAR1]] to i16
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; CHECK-NEXT: ret i16 [[VAR2]]
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entry:
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%0 = tail call i64 @llvm.ctlz.i64(i64 %x, i1 true)
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%cast = trunc i64 %0 to i16
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%tobool = icmp ne i64 %x, 0
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%cond = select i1 %tobool, i16 %cast, i16 64
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ret i16 %cond
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}
|
||||
|
||||
define i32 @test5d(i64 %x) {
|
||||
; CHECK-LABEL: @test5d(
|
||||
; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i64 @llvm.ctlz.i64(i64 %x, i1 false)
|
||||
; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = trunc i64 [[VAR1]] to i32
|
||||
; CHECK-NEXT: ret i32 [[VAR2]]
|
||||
entry:
|
||||
%0 = tail call i64 @llvm.ctlz.i64(i64 %x, i1 true)
|
||||
%cast = trunc i64 %0 to i32
|
||||
%tobool = icmp ne i64 %x, 0
|
||||
%cond = select i1 %tobool, i32 %cast, i32 64
|
||||
ret i32 %cond
|
||||
}
|
||||
|
||||
define i16 @test6d(i32 %x) {
|
||||
; CHECK-LABEL: @test6d(
|
||||
; CHECK: [[VAR1:%[a-zA-Z0-9]+]] = tail call i32 @llvm.ctlz.i32(i32 %x, i1 false)
|
||||
; CHECK-NEXT: [[VAR2:%[a-zA-Z0-9]+]] = trunc i32 [[VAR1]] to i16
|
||||
; CHECK-NEXT: ret i16 [[VAR2]]
|
||||
entry:
|
||||
%0 = tail call i32 @llvm.ctlz.i32(i32 %x, i1 true)
|
||||
%cast = trunc i32 %0 to i16
|
||||
%tobool = icmp ne i32 %x, 0
|
||||
%cond = select i1 %tobool, i16 %cast, i16 32
|
||||
ret i16 %cond
|
||||
}
|
||||
|
||||
declare i16 @llvm.ctlz.i16(i16, i1)
|
||||
declare i32 @llvm.ctlz.i32(i32, i1)
|
||||
declare i64 @llvm.ctlz.i64(i64, i1)
|
||||
declare i16 @llvm.cttz.i16(i16, i1)
|
||||
declare i32 @llvm.cttz.i32(i32, i1)
|
||||
declare i64 @llvm.cttz.i64(i64, i1)
|
||||
Loading…
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Reference in New Issue
Block a user