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Improve handling of SelectInst.
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Reorder operations to remove duplicated work.
Fix to leave floating-point types out of the optimization.
Add tests to predsimplify.ll for SwitchInst and SelectInst handling.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30055 91177308-0d34-0410-b5e6-96231b3b80d8
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@nlewycky
nlewycky committed Sep 2, 2006
1 parent 9442599 commit a3a68bd
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Showing 3 changed files with 229 additions and 32 deletions.
75 changes: 44 additions & 31 deletions lib/Transforms/Scalar/PredicateSimplifier.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -28,9 +28,6 @@
//
//===------------------------------------------------------------------===//

// TODO:
// * Check handling of NAN in floating point types

#define DEBUG_TYPE "predsimplify"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Constants.h"
Expand Down Expand Up @@ -112,14 +109,22 @@ namespace {
}

void addEqual(Value *V1, Value *V2) {
// If %x = 0. and %y = -0., seteq %x, %y is true, but
// copysign(%x) is not the same as copysign(%y).
if (V2->getType()->isFloatingPoint()) return;

order(V1, V2);
if (isa<Constant>(V2)) return; // refuse to set false == true.

DEBUG(std::cerr << "equal: " << *V1 << " and " << *V2 << "\n");
union_find.unionSets(V1, V2);
addImpliedProperties(EQ, V1, V2);
}

void addNotEqual(Value *V1, Value *V2) {
// If %x = NAN then seteq %x, %x is false.
if (V2->getType()->isFloatingPoint()) return;

DEBUG(std::cerr << "not equal: " << *V1 << " and " << *V2 << "\n");
if (findProperty(NE, V1, V2) != Properties.end())
return; // found.
Expand Down Expand Up @@ -180,15 +185,9 @@ namespace {
struct Property {
Property(Ops opcode, Value *v1, Value *v2)
: Opcode(opcode), V1(v1), V2(v2)
{ assert(opcode != EQ && "Equality belongs in the synonym set,"
{ assert(opcode != EQ && "Equality belongs in the synonym set, "
"not a property."); }

bool operator<(const Property &rhs) const {
if (Opcode != rhs.Opcode) return Opcode < rhs.Opcode;
if (V1 != rhs.V1) return V1 < rhs.V1;
return V2 < rhs.V2;
}

Ops Opcode;
Value *V1, *V2;
};
Expand All @@ -208,7 +207,7 @@ namespace {
}
}

// Finds the properties implied by a synonym and adds them too.
// Finds the properties implied by a equivalence and adds them too.
// Example: ("seteq %a, %b", true, EQ) --> (%a, %b, EQ)
// ("seteq %a, %b", false, EQ) --> (%a, %b, NE)
void addImpliedProperties(Ops Opcode, Value *V1, Value *V2) {
Expand Down Expand Up @@ -267,13 +266,25 @@ namespace {
default:
break;
}
} else if (SelectInst *SI = dyn_cast<SelectInst>(V2)) {
if (Opcode != EQ && Opcode != NE) return;

ConstantBool *True = (Opcode==EQ) ? ConstantBool::True
: ConstantBool::False,
*False = (Opcode==EQ) ? ConstantBool::False
: ConstantBool::True;

if (V1 == SI->getTrueValue())
addEqual(SI->getCondition(), True);
else if (V1 == SI->getFalseValue())
addEqual(SI->getCondition(), False);
else if (Opcode == EQ)
assert("Result of select not equal to either value.");
}
}

std::map<Value *, unsigned> SynonymMap;
std::vector<Value *> Synonyms;

public:
#ifdef DEBUG
void debug(std::ostream &os) const {
for (EquivalenceClasses<Value*>::iterator I = union_find.begin(),
E = union_find.end(); I != E; ++I) {
Expand All @@ -284,6 +295,7 @@ namespace {
std::cerr << "\n--\n";
}
}
#endif

std::vector<Property> Properties;
};
Expand Down Expand Up @@ -351,13 +363,13 @@ void PredicateSimplifier::getAnalysisUsage(AnalysisUsage &AU) const {

// resolve catches cases addProperty won't because it wasn't used as a
// condition in the branch, and that visit won't, because the instruction
// was defined outside of the range that the properties apply to.
// was defined outside of the scope that the properties apply to.
Value *PredicateSimplifier::resolve(SetCondInst *SCI,
const PropertySet &KP) {
// Attempt to resolve the SetCondInst to a boolean.

Value *SCI0 = SCI->getOperand(0),
*SCI1 = SCI->getOperand(1);
Value *SCI0 = resolve(SCI->getOperand(0), KP),
*SCI1 = resolve(SCI->getOperand(1), KP);
PropertySet::ConstPropertyIterator NE =
KP.findProperty(PropertySet::NE, SCI0, SCI1);

Expand All @@ -378,9 +390,6 @@ Value *PredicateSimplifier::resolve(SetCondInst *SCI,
}
}

SCI0 = KP.canonicalize(SCI0);
SCI1 = KP.canonicalize(SCI1);

ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(SCI0),
*CI2 = dyn_cast<ConstantIntegral>(SCI1);

Expand Down Expand Up @@ -445,6 +454,8 @@ Value *PredicateSimplifier::resolve(Value *V, const PropertySet &KP) {

V = KP.canonicalize(V);

DEBUG(std::cerr << "peering into " << *V << "\n");

if (BinaryOperator *BO = dyn_cast<BinaryOperator>(V))
return resolve(BO, KP);
else if (SelectInst *SI = dyn_cast<SelectInst>(V))
Expand All @@ -466,8 +477,19 @@ void PredicateSimplifier::visit(Instruction *I, DominatorTree::Node *DTNode,
DEBUG(std::cerr << "Considering instruction " << *I << "\n");
DEBUG(KnownProperties.debug(std::cerr));

// Substitute values known to be equal.
for (unsigned i = 0, E = I->getNumOperands(); i != E; ++i) {
// Try to replace whole instruction.
Value *V = resolve(I, KnownProperties);
assert(V && "resolve not supposed to return NULL.");
if (V != I) {
modified = true;
++NumInstruction;
I->replaceAllUsesWith(V);
I->eraseFromParent();
return;
}

// Try to substitute operands.
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
Value *Oper = I->getOperand(i);
Value *V = resolve(Oper, KnownProperties);
assert(V && "resolve not supposed to return NULL.");
Expand All @@ -480,15 +502,6 @@ void PredicateSimplifier::visit(Instruction *I, DominatorTree::Node *DTNode,
}
}

Value *V = resolve(I, KnownProperties);
assert(V && "resolve not supposed to return NULL.");
if (V != I) {
modified = true;
++NumInstruction;
I->replaceAllUsesWith(V);
I->eraseFromParent();
}

if (TerminatorInst *TI = dyn_cast<TerminatorInst>(I))
visit(TI, DTNode, KnownProperties);
else if (LoadInst *LI = dyn_cast<LoadInst>(I))
Expand Down
22 changes: 22 additions & 0 deletions test/Transforms/PredicateSimplifier/2006-08-02-Switch.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,22 @@
; RUN: llvm-as < %s | opt -predsimplify -disable-output

fastcc void %_ov_splice(int %n1, int %n2, int %ch2) {
entry:
%tmp = setgt int %n1, %n2 ; <bool> [#uses=1]
%n.0 = select bool %tmp, int %n2, int %n1 ; <int> [#uses=1]
%tmp104 = setlt int 0, %ch2 ; <bool> [#uses=1]
br bool %tmp104, label %cond_true105, label %return

cond_true95: ; preds = %cond_true105
ret void

bb98: ; preds = %cond_true105
ret void

cond_true105: ; preds = %entry
%tmp94 = setgt int %n.0, 0 ; <bool> [#uses=1]
br bool %tmp94, label %cond_true95, label %bb98

return: ; preds = %entry
ret void
}
164 changes: 163 additions & 1 deletion test/Transforms/PredicateSimplifier/predsimplify.ll
View file
Original file line number Diff line number Diff line change
@@ -1,4 +1,5 @@
; RUN: llvm-as < %s | opt -predsimplify -instcombine -simplifycfg | llvm-dis | grep -v declare | not grep fail
; RUN: llvm-as < %s | opt -predsimplify -instcombine -simplifycfg | llvm-dis | grep -v declare | not grep fail &&
; RUN: llvm-as < %s | opt -predsimplify -instcombine -simplifycfg | llvm-dis | grep -v declare | grep pass | wc -l | grep 3

void %test1(int %x) {
entry:
Expand Down Expand Up @@ -124,6 +125,167 @@ else.2:
ret void
}

void %test9(int %y, int %z) {
entry:
%x = add int %y, %z
%A = seteq int %y, 3
%B = seteq int %z, 5
%C = and bool %A, %B
br bool %C, label %cond_true, label %return

cond_true:
%D = seteq int %x, 8
br bool %D, label %then, label %oops

then:
call void (...)* %pass( )
ret void

oops:
call void (...)* %fail( )
ret void

return:
ret void
}

void %switch1(int %x) {
entry:
%A = seteq int %x, 10
br bool %A, label %return, label %cond_false

cond_false:
switch int %x, label %return [
int 9, label %then1
int 10, label %then2
]

then1:
call void (...)* %pass( )
ret void

then2:
call void (...)* %fail( )
ret void

return:
ret void
}

void %switch2(int %x) {
entry:
%A = seteq int %x, 10
br bool %A, label %return, label %cond_false

cond_false:
switch int %x, label %return [
int 8, label %then1
int 9, label %then1
int 10, label %then1
]

then1:
%B = setne int %x, 8
br bool %B, label %then2, label %return

then2:
call void (...)* %pass( )
ret void

return:
ret void
}

void %switch3(int %x) {
entry:
%A = seteq int %x, 10
br bool %A, label %return, label %cond_false

cond_false:
switch int %x, label %return [
int 9, label %then1
int 10, label %then1
]

then1:
%B = seteq int %x, 9
br bool %B, label %return, label %oops

oops:
call void (...)* %fail( )
ret void

return:
ret void
}

void %switch4(int %x) {
entry:
%A = seteq int %x, 10
br bool %A, label %then1, label %cond_false

cond_false:
switch int %x, label %default [
int 9, label %then1
int 10, label %then2
]

then1:
ret void

then2:
ret void

default:
%B = seteq int %x, 9
br bool %B, label %oops, label %then1

oops:
call void (...)* %fail( )
ret void
}

void %select1(int %x) {
entry:
%A = seteq int %x, 10
%B = select bool %A, int 1, int 2
%C = seteq int %B, 1
br bool %C, label %then, label %else

then:
br bool %A, label %return, label %oops

else:
br bool %A, label %oops, label %return

oops:
call void (...)* %fail( )
ret void

return:
ret void
}

void %select2(int %x) {
entry:
%A = seteq int %x, 10
%B = select bool %A, int 1, int 2
%C = seteq int %B, 1
br bool %A, label %then, label %else

then:
br bool %C, label %return, label %oops

else:
br bool %C, label %oops, label %return

oops:
call void (...)* %fail( )
ret void

return:
ret void
}

declare void %fail(...)

Expand Down

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