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[InlineCost] add visitSelectInst()
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InlineCost can understand Select IR now.  This patch finds free Select IRs and
continue the propagation of SimplifiedValues, ConstantOffsetPtrs, and
SROAArgValues.

Differential Revision: https://reviews.llvm.org/D37198

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@314307 91177308-0d34-0410-b5e6-96231b3b80d8
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Haicheng Wu committed Sep 27, 2017
1 parent 9da33de commit ba6de61
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82 changes: 82 additions & 0 deletions lib/Analysis/InlineCost.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -241,6 +241,7 @@ class CallAnalyzer : public InstVisitor<CallAnalyzer, bool> {
bool visitCallSite(CallSite CS);
bool visitReturnInst(ReturnInst &RI);
bool visitBranchInst(BranchInst &BI);
bool visitSelectInst(SelectInst &SI);
bool visitSwitchInst(SwitchInst &SI);
bool visitIndirectBrInst(IndirectBrInst &IBI);
bool visitResumeInst(ResumeInst &RI);
Expand Down Expand Up @@ -1177,6 +1178,87 @@ bool CallAnalyzer::visitBranchInst(BranchInst &BI) {
SimplifiedValues.lookup(BI.getCondition()));
}

bool CallAnalyzer::visitSelectInst(SelectInst &SI) {
bool CheckSROA = SI.getType()->isPointerTy();
Value *TrueVal = SI.getTrueValue();
Value *FalseVal = SI.getFalseValue();

Constant *TrueC = dyn_cast<Constant>(TrueVal);
if (!TrueC)
TrueC = SimplifiedValues.lookup(TrueVal);
Constant *FalseC = dyn_cast<Constant>(FalseVal);
if (!FalseC)
FalseC = SimplifiedValues.lookup(FalseVal);
Constant *CondC =
dyn_cast_or_null<Constant>(SimplifiedValues.lookup(SI.getCondition()));

if (!CondC) {
// Select C, X, X => X
if (TrueC == FalseC && TrueC) {
SimplifiedValues[&SI] = TrueC;
return true;
}

if (!CheckSROA)
return Base::visitSelectInst(SI);

std::pair<Value *, APInt> TrueBaseAndOffset =
ConstantOffsetPtrs.lookup(TrueVal);
std::pair<Value *, APInt> FalseBaseAndOffset =
ConstantOffsetPtrs.lookup(FalseVal);
if (TrueBaseAndOffset == FalseBaseAndOffset && TrueBaseAndOffset.first) {
ConstantOffsetPtrs[&SI] = TrueBaseAndOffset;

Value *SROAArg;
DenseMap<Value *, int>::iterator CostIt;
if (lookupSROAArgAndCost(TrueVal, SROAArg, CostIt))
SROAArgValues[&SI] = SROAArg;
return true;
}

return Base::visitSelectInst(SI);
}

// Select condition is a constant.
Value *SelectedV = CondC->isAllOnesValue()
? TrueVal
: (CondC->isNullValue()) ? FalseVal : nullptr;
if (!SelectedV) {
// Condition is a vector constant that is not all 1s or all 0s. If all
// operands are constants, ConstantExpr::getSelect() can handle the cases
// such as select vectors.
if (TrueC && FalseC) {
if (auto *C = ConstantExpr::getSelect(CondC, TrueC, FalseC)) {
SimplifiedValues[&SI] = C;
return true;
}
}
return Base::visitSelectInst(SI);
}

// Condition is either all 1s or all 0s. SI can be simplified.
if (Constant *SelectedC = dyn_cast<Constant>(SelectedV)) {
SimplifiedValues[&SI] = SelectedC;
return true;
}

if (!CheckSROA)
return true;

std::pair<Value *, APInt> BaseAndOffset =
ConstantOffsetPtrs.lookup(SelectedV);
if (BaseAndOffset.first) {
ConstantOffsetPtrs[&SI] = BaseAndOffset;

Value *SROAArg;
DenseMap<Value *, int>::iterator CostIt;
if (lookupSROAArgAndCost(SelectedV, SROAArg, CostIt))
SROAArgValues[&SI] = SROAArg;
}

return true;
}

bool CallAnalyzer::visitSwitchInst(SwitchInst &SI) {
// We model unconditional switches as free, see the comments on handling
// branches.
Expand Down
251 changes: 251 additions & 0 deletions test/Transforms/Inline/AArch64/select.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,251 @@
; RUN: opt -inline -mtriple=aarch64--linux-gnu -S -o - < %s -inline-threshold=0 | FileCheck %s

target datalayout = "e-m:e-i8:8:32-i16:16:32-i64:64-i128:128-n32:64-S128"
target triple = "aarch64--linux-gnu"

declare void @pad()
@glbl = external global i32

define i32 @outer1(i1 %cond) {
; CHECK-LABEL: @outer1(
; CHECK-NOT: call i32 @inner1
%C = call i32 @inner1(i1 %cond, i32 1)
ret i32 %C
}

define i32 @inner1(i1 %cond, i32 %val) {
%select = select i1 %cond, i32 1, i32 %val ; Simplified to 1
call void @pad()
store i32 0, i32* @glbl
ret i32 %select ; Simplifies to ret i32 1
}


define i32 @outer2(i32 %val) {
; CHECK-LABEL: @outer2(
; CHECK-NOT: call i32 @inner2
%C = call i32 @inner2(i1 true, i32 %val)
ret i32 %C
}

define i32 @inner2(i1 %cond, i32 %val) {
%select = select i1 %cond, i32 1, i32 %val ; Simplifies to 1
call void @pad()
store i32 0, i32* @glbl
ret i32 %select ; Simplifies to ret i32 1
}


define i32 @outer3(i32 %val) {
; CHECK-LABEL: @outer3(
; CHECK-NOT: call i32 @inner3
%C = call i32 @inner3(i1 false, i32 %val)
ret i32 %C
}

define i32 @inner3(i1 %cond, i32 %val) {
%select = select i1 %cond, i32 %val, i32 -1 ; Simplifies to -1
call void @pad()
store i32 0, i32* @glbl
ret i32 %select ; Simplifies to ret i32 -1
}


define i32 @outer4() {
; CHECK-LABEL: @outer4(
; CHECK-NOT: call i32 @inner4
%C = call i32 @inner4(i1 true, i32 1, i32 -1)
ret i32 %C
}

define i32 @inner4(i1 %cond, i32 %val1, i32 %val2) {
%select = select i1 %cond, i32 %val1, i32 %val2 ; Simplifies to 1
call void @pad()
store i32 0, i32* @glbl
store i32 1, i32* @glbl
ret i32 %select ; Simplifies to ret i32 1
}


define i1 @outer5() {
; CHECK-LABEL: @outer5(
; CHECK-NOT: call i1 @inner5
%C = call i1 @inner5(i1 true, i1 true, i1 false)
ret i1 %C
}

declare void @dead()

define i1 @inner5(i1 %cond, i1 %val1, i1 %val2) {
%select = select i1 %cond, i1 %val1, i1 %val2 ; Simplifies to true
br i1 %select, label %exit, label %isfalse ; Simplifies to br label %end

isfalse: ; This block is unreachable once inlined
call void @dead()
br label %exit

exit:
store i32 0, i32* @glbl
ret i1 %select ; Simplifies to ret i1 true
}


define i32 @outer6(i1 %cond) {
; CHECK-LABEL: @outer6(
; CHECK-NOT: call i32 @inner6
%A = alloca i32
%C = call i32 @inner6(i1 %cond, i32* %A)
ret i32 %C
}

define i32 @inner6(i1 %cond, i32* %ptr) {
%G1 = getelementptr inbounds i32, i32* %ptr, i32 1
%G2 = getelementptr inbounds i32, i32* %G1, i32 1
%G3 = getelementptr inbounds i32, i32* %ptr, i32 2
%select = select i1 %cond, i32* %G2, i32* %G3 ; Simplified to %A[2]
%load = load i32, i32* %select ; SROA'ed
call void @pad()
ret i32 %load ; Simplified
}


define i32 @outer7(i32* %ptr) {
; CHECK-LABEL: @outer7(
; CHECK-NOT: call i32 @inner7
%A = alloca i32
%C = call i32 @inner7(i1 true, i32* %A, i32* %ptr)
ret i32 %C
}

define i32 @inner7(i1 %cond, i32* %p1, i32* %p2) {
%select = select i1 %cond, i32* %p1, i32* %p2 ; Simplifies to %A
%load = load i32, i32* %select ; SROA'ed
call void @pad()
store i32 0, i32* @glbl
ret i32 %load ; Simplified
}


define i32 @outer8(i32* %ptr) {
; CHECK-LABEL: @outer8(
; CHECK-NOT: call i32 @inner8
%A = alloca i32
%C = call i32 @inner8(i1 false, i32* %ptr, i32* %A)
ret i32 %C
}

define i32 @inner8(i1 %cond, i32* %p1, i32* %p2) {
%select = select i1 %cond, i32* %p1, i32* %p2 ; Simplifies to %A
%load = load i32, i32* %select ; SROA'ed
call void @pad()
store i32 0, i32* @glbl
ret i32 %load ; Simplified
}


define <2 x i32> @outer9(<2 x i32> %val) {
; CHECK-LABEL: @outer9(
; CHECK-NOT: call <2 x i32> @inner9
%C = call <2 x i32> @inner9(<2 x i1> <i1 true, i1 true>, <2 x i32> %val)
ret <2 x i32> %C
}

define <2 x i32> @inner9(<2 x i1> %cond, <2 x i32> %val) {
%select = select <2 x i1> %cond, <2 x i32> <i32 1, i32 1>, <2 x i32> %val ; Simplifies to <1, 1>
call void @pad()
store i32 0, i32* @glbl
ret <2 x i32> %select ; Simplifies to ret <2 x i32> <1, 1>
}


define <2 x i32> @outer10(<2 x i32> %val) {
; CHECK-LABEL: @outer10(
; CHECK-NOT: call <2 x i32> @inner10
%C = call <2 x i32> @inner10(<2 x i1> <i1 false, i1 false>, <2 x i32> %val)
ret <2 x i32> %C
}

define <2 x i32> @inner10(<2 x i1> %cond, <2 x i32> %val) {
%select = select <2 x i1> %cond, < 2 x i32> %val, <2 x i32> <i32 -1, i32 -1> ; Simplifies to <-1, -1>
call void @pad()
store i32 0, i32* @glbl
ret <2 x i32> %select ; Simplifies to ret <2 x i32> <-1, -1>
}


define <2 x i32> @outer11() {
; CHECK-LABEL: @outer11(
; CHECK-NOT: call <2 x i32> @inner11
%C = call <2 x i32> @inner11(<2 x i1> <i1 true, i1 false>)
ret <2 x i32> %C
}

define <2 x i32> @inner11(<2 x i1> %cond) {
%select = select <2 x i1> %cond, <2 x i32> <i32 1, i32 1>, < 2 x i32> <i32 -1, i32 -1> ; Simplifies to <1, -1>
call void @pad()
ret <2 x i32> %select ; Simplifies to ret <2 x i32> <1, -1>
}


define i1 @outer12(i32* %ptr) {
; CHECK-LABEL: @outer12(
; CHECK-NOT: call i1 @inner12
%C = call i1 @inner12(i1 true, i32* @glbl, i32* %ptr)
ret i1 %C
}

define i1 @inner12(i1 %cond, i32* %ptr1, i32* %ptr2) {
%select = select i1 %cond, i32* %ptr1, i32* %ptr2 ; Simplified to @glbl
%cmp = icmp eq i32* %select, @glbl ; Simplified to true
call void @pad()
store i32 0, i32* @glbl
ret i1 %cmp ; Simplifies to ret i1 true
}


define <2 x i32> @outer13(<2 x i32> %val1, <2 x i32> %val2) {
; CHECK-LABEL: @outer13(
; CHECK: call <2 x i32> @inner13
%C = call <2 x i32> @inner13(<2 x i1> <i1 true, i1 false>, <2 x i32> %val1, <2 x i32> %val2)
ret <2 x i32> %C
}

define <2 x i32> @inner13(<2 x i1> %cond, <2 x i32> %val1, < 2 x i32> %val2) {
%select = select <2 x i1> %cond, <2 x i32> %val1, < 2 x i32> %val2 ; Cannot be Simplified
call void @pad()
store i32 0, i32* @glbl
store i32 1, i32* @glbl
ret <2 x i32> %select ; Simplified
}


define i32 @outer14(i32 %val1, i32 %val2) {
; CHECK-LABEL: @outer14(
; CHECK-NOT: call i32 @inner14
%C = call i32 @inner14(i1 true, i32 %val1, i32 %val2)
ret i32 %C
}

define i32 @inner14(i1 %cond, i32 %val1, i32 %val2) {
%select = select i1 %cond, i32 %val1, i32 %val2 ; Simplified to %val1
call void @pad()
store i32 0, i32* @glbl
store i32 1, i32* @glbl
ret i32 %select ; Simplifies to ret i32 %val1
}


define i32 @outer15(i32 %val1, i32 %val2) {
; CHECK-LABEL: @outer15(
; CHECK-NOT: call i32 @inner15
%C = call i32 @inner15(i1 false, i32 %val1, i32 %val2)
ret i32 %C
}

define i32 @inner15(i1 %cond, i32 %val1, i32 %val2) {
%select = select i1 %cond, i32 %val1, i32 %val2 ; Simplified to %val2
call void @pad()
store i32 0, i32* @glbl
store i32 1, i32* @glbl
ret i32 %select ; Simplifies to ret i32 %val2
}

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