[llvm-commits] [llvm] r52442 - in /llvm/trunk: lib/Transforms/Scalar/InstructionCombining.cpp test/Transforms/InstCombine/bswap-fold.ll
Chris Lattner
sabre at nondot.org
Tue Jun 17 21:33:21 PDT 2008
Author: lattner
Date: Tue Jun 17 23:33:20 2008
New Revision: 52442
URL: http://llvm.org/viewvc/llvm-project?rev=52442&view=rev
Log:
implement some simple bswap optimizations, rdar://5992453
Modified:
llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll
Modified: llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp?rev=52442&r1=52441&r2=52442&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/InstructionCombining.cpp Tue Jun 17 23:33:20 2008
@@ -1304,6 +1304,46 @@
KnownZero = APInt::getHighBitsSet(BitWidth, Leaders) & DemandedMask;
break;
}
+ case Instruction::Call:
+ if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::bswap: {
+ // If the only bits demanded come from one byte of the bswap result,
+ // just shift the input byte into position to eliminate the bswap.
+ unsigned NLZ = DemandedMask.countLeadingZeros();
+ unsigned NTZ = DemandedMask.countTrailingZeros();
+
+ // Round NTZ down to the next byte. If we have 11 trailing zeros, then
+ // we need all the bits down to bit 8. Likewise, round NLZ. If we
+ // have 14 leading zeros, round to 8.
+ NLZ &= ~7;
+ NTZ &= ~7;
+ // If we need exactly one byte, we can do this transformation.
+ if (BitWidth-NLZ-NTZ == 8) {
+ unsigned ResultBit = NTZ;
+ unsigned InputBit = BitWidth-NTZ-8;
+
+ // Replace this with either a left or right shift to get the byte into
+ // the right place.
+ Instruction *NewVal;
+ if (InputBit > ResultBit)
+ NewVal = BinaryOperator::CreateLShr(I->getOperand(1),
+ ConstantInt::get(I->getType(), InputBit-ResultBit));
+ else
+ NewVal = BinaryOperator::CreateShl(I->getOperand(1),
+ ConstantInt::get(I->getType(), ResultBit-InputBit));
+ NewVal->takeName(I);
+ InsertNewInstBefore(NewVal, *I);
+ return UpdateValueUsesWith(I, NewVal);
+ }
+
+ // TODO: Could compute known zero/one bits based on the input.
+ break;
+ }
+ }
+ }
+ break;
}
// If the client is only demanding bits that we know, return the known
@@ -8533,144 +8573,150 @@
}
if (Changed) return II;
- } else {
- switch (II->getIntrinsicID()) {
- default: break;
- case Intrinsic::ppc_altivec_lvx:
- case Intrinsic::ppc_altivec_lvxl:
- case Intrinsic::x86_sse_loadu_ps:
- case Intrinsic::x86_sse2_loadu_pd:
- case Intrinsic::x86_sse2_loadu_dq:
- // Turn PPC lvx -> load if the pointer is known aligned.
- // Turn X86 loadups -> load if the pointer is known aligned.
- if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
- Value *Ptr = InsertBitCastBefore(II->getOperand(1),
- PointerType::getUnqual(II->getType()),
- CI);
- return new LoadInst(Ptr);
- }
- break;
- case Intrinsic::ppc_altivec_stvx:
- case Intrinsic::ppc_altivec_stvxl:
- // Turn stvx -> store if the pointer is known aligned.
- if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
- const Type *OpPtrTy =
- PointerType::getUnqual(II->getOperand(1)->getType());
- Value *Ptr = InsertBitCastBefore(II->getOperand(2), OpPtrTy, CI);
- return new StoreInst(II->getOperand(1), Ptr);
- }
- break;
- case Intrinsic::x86_sse_storeu_ps:
- case Intrinsic::x86_sse2_storeu_pd:
- case Intrinsic::x86_sse2_storeu_dq:
- case Intrinsic::x86_sse2_storel_dq:
- // Turn X86 storeu -> store if the pointer is known aligned.
- if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
- const Type *OpPtrTy =
- PointerType::getUnqual(II->getOperand(2)->getType());
- Value *Ptr = InsertBitCastBefore(II->getOperand(1), OpPtrTy, CI);
- return new StoreInst(II->getOperand(2), Ptr);
- }
- break;
-
- case Intrinsic::x86_sse_cvttss2si: {
- // These intrinsics only demands the 0th element of its input vector. If
- // we can simplify the input based on that, do so now.
- uint64_t UndefElts;
- if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), 1,
- UndefElts)) {
- II->setOperand(1, V);
- return II;
- }
- break;
+ }
+
+ switch (II->getIntrinsicID()) {
+ default: break;
+ case Intrinsic::bswap:
+ // bswap(bswap(x)) -> x
+ if (IntrinsicInst *Operand = dyn_cast<IntrinsicInst>(II->getOperand(1)))
+ if (Operand->getIntrinsicID() == Intrinsic::bswap)
+ return ReplaceInstUsesWith(CI, Operand->getOperand(1));
+ break;
+ case Intrinsic::ppc_altivec_lvx:
+ case Intrinsic::ppc_altivec_lvxl:
+ case Intrinsic::x86_sse_loadu_ps:
+ case Intrinsic::x86_sse2_loadu_pd:
+ case Intrinsic::x86_sse2_loadu_dq:
+ // Turn PPC lvx -> load if the pointer is known aligned.
+ // Turn X86 loadups -> load if the pointer is known aligned.
+ if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
+ Value *Ptr = InsertBitCastBefore(II->getOperand(1),
+ PointerType::getUnqual(II->getType()),
+ CI);
+ return new LoadInst(Ptr);
+ }
+ break;
+ case Intrinsic::ppc_altivec_stvx:
+ case Intrinsic::ppc_altivec_stvxl:
+ // Turn stvx -> store if the pointer is known aligned.
+ if (GetOrEnforceKnownAlignment(II->getOperand(2), 16) >= 16) {
+ const Type *OpPtrTy =
+ PointerType::getUnqual(II->getOperand(1)->getType());
+ Value *Ptr = InsertBitCastBefore(II->getOperand(2), OpPtrTy, CI);
+ return new StoreInst(II->getOperand(1), Ptr);
+ }
+ break;
+ case Intrinsic::x86_sse_storeu_ps:
+ case Intrinsic::x86_sse2_storeu_pd:
+ case Intrinsic::x86_sse2_storeu_dq:
+ case Intrinsic::x86_sse2_storel_dq:
+ // Turn X86 storeu -> store if the pointer is known aligned.
+ if (GetOrEnforceKnownAlignment(II->getOperand(1), 16) >= 16) {
+ const Type *OpPtrTy =
+ PointerType::getUnqual(II->getOperand(2)->getType());
+ Value *Ptr = InsertBitCastBefore(II->getOperand(1), OpPtrTy, CI);
+ return new StoreInst(II->getOperand(2), Ptr);
}
+ break;
+
+ case Intrinsic::x86_sse_cvttss2si: {
+ // These intrinsics only demands the 0th element of its input vector. If
+ // we can simplify the input based on that, do so now.
+ uint64_t UndefElts;
+ if (Value *V = SimplifyDemandedVectorElts(II->getOperand(1), 1,
+ UndefElts)) {
+ II->setOperand(1, V);
+ return II;
+ }
+ break;
+ }
+
+ case Intrinsic::ppc_altivec_vperm:
+ // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
+ if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
+ assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
+
+ // Check that all of the elements are integer constants or undefs.
+ bool AllEltsOk = true;
+ for (unsigned i = 0; i != 16; ++i) {
+ if (!isa<ConstantInt>(Mask->getOperand(i)) &&
+ !isa<UndefValue>(Mask->getOperand(i))) {
+ AllEltsOk = false;
+ break;
+ }
+ }
- case Intrinsic::ppc_altivec_vperm:
- // Turn vperm(V1,V2,mask) -> shuffle(V1,V2,mask) if mask is a constant.
- if (ConstantVector *Mask = dyn_cast<ConstantVector>(II->getOperand(3))) {
- assert(Mask->getNumOperands() == 16 && "Bad type for intrinsic!");
+ if (AllEltsOk) {
+ // Cast the input vectors to byte vectors.
+ Value *Op0 =InsertBitCastBefore(II->getOperand(1),Mask->getType(),CI);
+ Value *Op1 =InsertBitCastBefore(II->getOperand(2),Mask->getType(),CI);
+ Value *Result = UndefValue::get(Op0->getType());
+
+ // Only extract each element once.
+ Value *ExtractedElts[32];
+ memset(ExtractedElts, 0, sizeof(ExtractedElts));
- // Check that all of the elements are integer constants or undefs.
- bool AllEltsOk = true;
for (unsigned i = 0; i != 16; ++i) {
- if (!isa<ConstantInt>(Mask->getOperand(i)) &&
- !isa<UndefValue>(Mask->getOperand(i))) {
- AllEltsOk = false;
- break;
- }
- }
-
- if (AllEltsOk) {
- // Cast the input vectors to byte vectors.
- Value *Op0 =InsertBitCastBefore(II->getOperand(1),Mask->getType(),CI);
- Value *Op1 =InsertBitCastBefore(II->getOperand(2),Mask->getType(),CI);
- Value *Result = UndefValue::get(Op0->getType());
-
- // Only extract each element once.
- Value *ExtractedElts[32];
- memset(ExtractedElts, 0, sizeof(ExtractedElts));
-
- for (unsigned i = 0; i != 16; ++i) {
- if (isa<UndefValue>(Mask->getOperand(i)))
- continue;
- unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
- Idx &= 31; // Match the hardware behavior.
-
- if (ExtractedElts[Idx] == 0) {
- Instruction *Elt =
- new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
- InsertNewInstBefore(Elt, CI);
- ExtractedElts[Idx] = Elt;
- }
+ if (isa<UndefValue>(Mask->getOperand(i)))
+ continue;
+ unsigned Idx=cast<ConstantInt>(Mask->getOperand(i))->getZExtValue();
+ Idx &= 31; // Match the hardware behavior.
- // Insert this value into the result vector.
- Result = InsertElementInst::Create(Result, ExtractedElts[Idx],
- i, "tmp");
- InsertNewInstBefore(cast<Instruction>(Result), CI);
+ if (ExtractedElts[Idx] == 0) {
+ Instruction *Elt =
+ new ExtractElementInst(Idx < 16 ? Op0 : Op1, Idx&15, "tmp");
+ InsertNewInstBefore(Elt, CI);
+ ExtractedElts[Idx] = Elt;
}
- return CastInst::Create(Instruction::BitCast, Result, CI.getType());
+
+ // Insert this value into the result vector.
+ Result = InsertElementInst::Create(Result, ExtractedElts[Idx],
+ i, "tmp");
+ InsertNewInstBefore(cast<Instruction>(Result), CI);
}
+ return CastInst::Create(Instruction::BitCast, Result, CI.getType());
}
- break;
+ }
+ break;
- case Intrinsic::stackrestore: {
- // If the save is right next to the restore, remove the restore. This can
- // happen when variable allocas are DCE'd.
- if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
- if (SS->getIntrinsicID() == Intrinsic::stacksave) {
- BasicBlock::iterator BI = SS;
- if (&*++BI == II)
- return EraseInstFromFunction(CI);
- }
+ case Intrinsic::stackrestore: {
+ // If the save is right next to the restore, remove the restore. This can
+ // happen when variable allocas are DCE'd.
+ if (IntrinsicInst *SS = dyn_cast<IntrinsicInst>(II->getOperand(1))) {
+ if (SS->getIntrinsicID() == Intrinsic::stacksave) {
+ BasicBlock::iterator BI = SS;
+ if (&*++BI == II)
+ return EraseInstFromFunction(CI);
}
-
- // Scan down this block to see if there is another stack restore in the
- // same block without an intervening call/alloca.
- BasicBlock::iterator BI = II;
- TerminatorInst *TI = II->getParent()->getTerminator();
- bool CannotRemove = false;
- for (++BI; &*BI != TI; ++BI) {
- if (isa<AllocaInst>(BI)) {
+ }
+
+ // Scan down this block to see if there is another stack restore in the
+ // same block without an intervening call/alloca.
+ BasicBlock::iterator BI = II;
+ TerminatorInst *TI = II->getParent()->getTerminator();
+ bool CannotRemove = false;
+ for (++BI; &*BI != TI; ++BI) {
+ if (isa<AllocaInst>(BI)) {
+ CannotRemove = true;
+ break;
+ }
+ if (isa<CallInst>(BI)) {
+ if (!isa<IntrinsicInst>(BI)) {
CannotRemove = true;
break;
}
- if (isa<CallInst>(BI)) {
- if (!isa<IntrinsicInst>(BI)) {
- CannotRemove = true;
- break;
- }
- // If there is a stackrestore below this one, remove this one.
- return EraseInstFromFunction(CI);
- }
- }
-
- // If the stack restore is in a return/unwind block and if there are no
- // allocas or calls between the restore and the return, nuke the restore.
- if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
+ // If there is a stackrestore below this one, remove this one.
return EraseInstFromFunction(CI);
- break;
- }
+ }
}
+
+ // If the stack restore is in a return/unwind block and if there are no
+ // allocas or calls between the restore and the return, nuke the restore.
+ if (!CannotRemove && (isa<ReturnInst>(TI) || isa<UnwindInst>(TI)))
+ return EraseInstFromFunction(CI);
+ break;
+ }
}
return visitCallSite(II);
Modified: llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll?rev=52442&r1=52441&r2=52442&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/bswap-fold.ll Tue Jun 17 23:33:20 2008
@@ -1,7 +1,5 @@
-; RUN: llvm-as < %s | opt -instcombine | llvm-dis | \
-; RUN: grep ret | count 3
-; RUN: llvm-as < %s | opt -instcombine | llvm-dis | \
-; RUN: not grep call.*bswap
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | grep ret | count 6
+; RUN: llvm-as < %s | opt -instcombine | llvm-dis | not grep call.*bswap
define i1 @test1(i16 %tmp2) {
%tmp10 = call i16 @llvm.bswap.i16( i16 %tmp2 ) ; <i16> [#uses=1]
@@ -27,3 +25,28 @@
declare i16 @llvm.bswap.i16(i16)
+; rdar://5992453
+; A & 255
+define i32 @test4(i32 %a) nounwind {
+entry:
+ %tmp2 = tail call i32 @llvm.bswap.i32( i32 %a )
+ %tmp4 = lshr i32 %tmp2, 24
+ ret i32 %tmp4
+}
+
+; A
+define i32 @test5(i32 %a) nounwind {
+entry:
+ %tmp2 = tail call i32 @llvm.bswap.i32( i32 %a )
+ %tmp4 = tail call i32 @llvm.bswap.i32( i32 %tmp2 )
+ ret i32 %tmp4
+}
+
+; a >> 24
+define i32 @test6(i32 %a) nounwind {
+entry:
+ %tmp2 = tail call i32 @llvm.bswap.i32( i32 %a )
+ %tmp4 = and i32 %tmp2, 255
+ ret i32 %tmp4
+}
+
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