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- Bug fixes.

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- Allow icmp rewrite using an iv / stride of a smaller integer type.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43480 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2007-10-29 22:07:18 +00:00
parent e476a66761
commit af62c09437
2 changed files with 104 additions and 10 deletions
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48
lib/Transforms/Scalar/LoopStrengthReduce.cpp
View File

@ -1476,6 +1476,8 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
uint64_t SignBit = 1ULL << (BitWidth-1);
const Type *CmpTy = C->getType();
const Type *NewCmpTy = NULL;
unsigned TyBits = CmpTy->getPrimitiveSizeInBits();
unsigned NewTyBits = 0;
int64_t NewCmpVal = CmpVal;
SCEVHandle *NewStride = NULL;
Value *NewIncV = NULL;
@ -1521,7 +1523,31 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
}
NewCmpTy = NewIncV->getType();
if (RequiresTypeConversion(CmpTy, NewCmpTy)) {
NewTyBits = isa<PointerType>(NewCmpTy)
? UIntPtrTy->getPrimitiveSizeInBits()
: NewCmpTy->getPrimitiveSizeInBits();
if (RequiresTypeConversion(NewCmpTy, CmpTy)) {
// Check if it is possible to rewrite it using a iv / stride of a smaller
// integer type.
bool TruncOk = false;
if (NewCmpTy->isInteger()) {
unsigned Bits = NewTyBits;
if (ICmpInst::isSignedPredicate(Predicate))
--Bits;
uint64_t Mask = (1ULL << Bits) - 1;
if (((uint64_t)NewCmpVal & Mask) == (uint64_t)NewCmpVal)
TruncOk = true;
}
if (!TruncOk) {
NewCmpVal = CmpVal;
continue;
}
}
// Don't rewrite if use offset is non-constant and the new type is
// of a different type.
// FIXME: too conservative?
if (NewTyBits != TyBits && !isa<SCEVConstant>(CondUse->Offset)) {
NewCmpVal = CmpVal;
continue;
}
@ -1552,13 +1578,12 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
if (NewCmpVal != CmpVal) {
// Create a new compare instruction using new stride / iv.
ICmpInst *OldCond = Cond;
Value *RHS = ConstantInt::get(C->getType(), NewCmpVal);
// Both sides of a ICmpInst must be of the same type.
if (NewCmpTy != CmpTy) {
if (isa<PointerType>(NewCmpTy) && !isa<PointerType>(CmpTy))
RHS= SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, RHS, NewCmpTy);
else
RHS = SCEVExpander::InsertCastOfTo(Instruction::BitCast, RHS, NewCmpTy);
Value *RHS;
if (!isa<PointerType>(NewCmpTy))
RHS = ConstantInt::get(NewCmpTy, NewCmpVal);
else {
RHS = ConstantInt::get(UIntPtrTy, NewCmpVal);
RHS = SCEVExpander::InsertCastOfTo(Instruction::IntToPtr, RHS, NewCmpTy);
}
// Insert new compare instruction.
Cond = new ICmpInst(Predicate, NewIncV, RHS);
@ -1572,8 +1597,11 @@ ICmpInst *LoopStrengthReduce::ChangeCompareStride(Loop *L, ICmpInst *Cond,
OldCond->eraseFromParent();
IVUsesByStride[*CondStride].Users.pop_back();
SCEVHandle NewOffset = SE->getMulExpr(CondUse->Offset,
SE->getConstant(ConstantInt::get(CondUse->Offset->getType(), Scale)));
SCEVHandle NewOffset = TyBits == NewTyBits
? SE->getMulExpr(CondUse->Offset,
SE->getConstant(ConstantInt::get(CmpTy, Scale)))
: SE->getConstant(ConstantInt::get(NewCmpTy,
cast<SCEVConstant>(CondUse->Offset)->getValue()->getSExtValue()*Scale));
IVUsesByStride[*NewStride].addUser(NewOffset, Cond, NewIncV);
CondUse = &IVUsesByStride[*NewStride].Users.back();
CondStride = NewStride;

66
test/CodeGen/X86/loop-strength-reduce6.ll Normal file
View File

@ -0,0 +1,66 @@
; RUN: llvm-as < %s | llc -march=x86-64 | not grep inc
define fastcc i32 @decodeMP3(i32 %isize, i32* %done) {
entry:
br i1 false, label %cond_next191, label %cond_true189
cond_true189: ; preds = %entry
ret i32 0
cond_next191: ; preds = %entry
br i1 false, label %cond_next37.i, label %cond_false.i9
cond_false.i9: ; preds = %cond_next191
ret i32 0
cond_next37.i: ; preds = %cond_next191
br i1 false, label %cond_false50.i, label %cond_true44.i
cond_true44.i: ; preds = %cond_next37.i
br i1 false, label %cond_true11.i.i, label %bb414.preheader.i
cond_true11.i.i: ; preds = %cond_true44.i
ret i32 0
cond_false50.i: ; preds = %cond_next37.i
ret i32 0
bb414.preheader.i: ; preds = %cond_true44.i
br i1 false, label %bb.i18, label %do_layer3.exit
bb.i18: ; preds = %bb414.preheader.i
br i1 false, label %bb358.i, label %cond_true79.i
cond_true79.i: ; preds = %bb.i18
ret i32 0
bb331.i: ; preds = %bb358.i, %cond_true.i149.i
br i1 false, label %cond_true.i149.i, label %cond_false.i151.i
cond_true.i149.i: ; preds = %bb331.i
br i1 false, label %bb178.preheader.i.i, label %bb331.i
cond_false.i151.i: ; preds = %bb331.i
ret i32 0
bb163.i.i: ; preds = %bb178.preheader.i.i, %bb163.i.i
%rawout2.451.rec.i.i = phi i64 [ 0, %bb178.preheader.i.i ], [ %indvar.next260.i, %bb163.i.i ] ; <i64> [#uses=2]
%i.052.i.i = trunc i64 %rawout2.451.rec.i.i to i32 ; <i32> [#uses=1]
%tmp165.i144.i = shl i32 %i.052.i.i, 5 ; <i32> [#uses=1]
%tmp165169.i.i = sext i32 %tmp165.i144.i to i64 ; <i64> [#uses=0]
%indvar.next260.i = add i64 %rawout2.451.rec.i.i, 1 ; <i64> [#uses=2]
%exitcond261.i = icmp eq i64 %indvar.next260.i, 18 ; <i1> [#uses=1]
br i1 %exitcond261.i, label %bb178.preheader.i.i, label %bb163.i.i
bb178.preheader.i.i: ; preds = %bb163.i.i, %cond_true.i149.i
br label %bb163.i.i
bb358.i: ; preds = %bb.i18
br i1 false, label %bb331.i, label %bb406.i
bb406.i: ; preds = %bb358.i
ret i32 0
do_layer3.exit: ; preds = %bb414.preheader.i
ret i32 0
}