[llvm] r243939 - Revert "[LSR] Generate and use zero extends"
Sanjoy Das
sanjoy at playingwithpointers.com
Mon Aug 3 18:52:05 PDT 2015
Author: sanjoy
Date: Mon Aug 3 20:52:05 2015
New Revision: 243939
URL: http://llvm.org/viewvc/llvm-project?rev=243939&view=rev
Log:
Revert "[LSR] Generate and use zero extends"
This reverts commit r243348 and r243357. They caused PR24347.
Removed:
llvm/trunk/test/Transforms/LoopStrengthReduce/X86/zext-of-scale.ll
Modified:
llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp?rev=243939&r1=243938&r2=243939&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopStrengthReduce.cpp Mon Aug 3 20:52:05 2015
@@ -256,22 +256,9 @@ struct Formula {
/// live in an add immediate field rather than a register.
int64_t UnfoldedOffset;
- /// ZeroExtendScaledReg - This formula zero extends the scale register to
- /// ZeroExtendType before its use.
- bool ZeroExtendScaledReg;
-
- /// ZeroExtendBaseReg - This formula zero extends all the base registers to
- /// ZeroExtendType before their use.
- bool ZeroExtendBaseReg;
-
- /// ZeroExtendType - The destination type of the zero extension implied by
- /// the above two booleans.
- Type *ZeroExtendType;
-
Formula()
: BaseGV(nullptr), BaseOffset(0), HasBaseReg(false), Scale(0),
- ScaledReg(nullptr), UnfoldedOffset(0), ZeroExtendScaledReg(false),
- ZeroExtendBaseReg(false), ZeroExtendType(nullptr) {}
+ ScaledReg(nullptr), UnfoldedOffset(0) {}
void InitialMatch(const SCEV *S, Loop *L, ScalarEvolution &SE);
@@ -426,12 +413,10 @@ size_t Formula::getNumRegs() const {
/// getType - Return the type of this formula, if it has one, or null
/// otherwise. This type is meaningless except for the bit size.
Type *Formula::getType() const {
- return ZeroExtendType
- ? ZeroExtendType
- : !BaseRegs.empty()
- ? BaseRegs.front()->getType()
- : ScaledReg ? ScaledReg->getType()
- : BaseGV ? BaseGV->getType() : nullptr;
+ return !BaseRegs.empty() ? BaseRegs.front()->getType() :
+ ScaledReg ? ScaledReg->getType() :
+ BaseGV ? BaseGV->getType() :
+ nullptr;
}
/// DeleteBaseReg - Delete the given base reg from the BaseRegs list.
@@ -472,10 +457,7 @@ void Formula::print(raw_ostream &OS) con
}
for (const SCEV *BaseReg : BaseRegs) {
if (!First) OS << " + "; else First = false;
- if (ZeroExtendBaseReg)
- OS << "reg(zext " << *BaseReg << " to " << *ZeroExtendType << ')';
- else
- OS << "reg(" << *BaseReg << ')';
+ OS << "reg(" << *BaseReg << ')';
}
if (HasBaseReg && BaseRegs.empty()) {
if (!First) OS << " + "; else First = false;
@@ -487,12 +469,9 @@ void Formula::print(raw_ostream &OS) con
if (Scale != 0) {
if (!First) OS << " + "; else First = false;
OS << Scale << "*reg(";
- if (ScaledReg) {
- if (ZeroExtendScaledReg)
- OS << "(zext " << *ScaledReg << " to " << *ZeroExtendType << ')';
- else
- OS << *ScaledReg;
- } else
+ if (ScaledReg)
+ OS << *ScaledReg;
+ else
OS << "<unknown>";
OS << ')';
}
@@ -1753,7 +1732,6 @@ class LSRInstance {
void GenerateICmpZeroScales(LSRUse &LU, unsigned LUIdx, Formula Base);
void GenerateScales(LSRUse &LU, unsigned LUIdx, Formula Base);
void GenerateTruncates(LSRUse &LU, unsigned LUIdx, Formula Base);
- void GenerateZExts(LSRUse &LU, unsigned LUIdx, Formula Base);
void GenerateCrossUseConstantOffsets();
void GenerateAllReuseFormulae();
@@ -3649,64 +3627,6 @@ void LSRInstance::GenerateTruncates(LSRU
}
}
-/// GenerateZExts - If a scale or a base register can be rewritten as
-/// "Zext({A,+,1})" then consider a formula of that form.
-void LSRInstance::GenerateZExts(LSRUse &LU, unsigned LUIdx, Formula Base) {
- // Don't bother with symbolic values.
- if (Base.BaseGV)
- return;
-
- auto CanBeNarrowed = [&](const SCEV *Reg) -> const SCEV * {
- // Check if the register is an increment can be rewritten as zext(R) where
- // the zext is free.
-
- const auto *RegAR = dyn_cast_or_null<SCEVAddRecExpr>(Reg);
- if (!RegAR)
- return nullptr;
-
- const auto *ZExtStart = dyn_cast<SCEVZeroExtendExpr>(RegAR->getStart());
- const auto *ConstStep =
- dyn_cast<SCEVConstant>(RegAR->getStepRecurrence(SE));
- if (!ZExtStart || !ConstStep || ConstStep->getValue()->getValue() != 1)
- return nullptr;
-
- const SCEV *NarrowStart = ZExtStart->getOperand();
- if (!TTI.isZExtFree(NarrowStart->getType(), ZExtStart->getType()))
- return nullptr;
-
- const auto *NarrowAR = dyn_cast<SCEVAddRecExpr>(
- SE.getAddRecExpr(NarrowStart, SE.getConstant(NarrowStart->getType(), 1),
- RegAR->getLoop(), RegAR->getNoWrapFlags()));
-
- if (!NarrowAR || !NarrowAR->getNoWrapFlags(SCEV::FlagNUW))
- return nullptr;
-
- return NarrowAR;
- };
-
- if (Base.ScaledReg && !Base.ZeroExtendType)
- if (const SCEV *S = CanBeNarrowed(Base.ScaledReg)) {
- Formula F = Base;
- F.ZeroExtendType = Base.ScaledReg->getType();
- F.ZeroExtendScaledReg = true;
- F.ScaledReg = S;
-
- if (isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
- InsertFormula(LU, LUIdx, F);
- }
-
- if (Base.BaseRegs.size() == 1 && !Base.ZeroExtendType)
- if (const SCEV *S = CanBeNarrowed(Base.BaseRegs[0])) {
- Formula F = Base;
- F.ZeroExtendType = Base.BaseRegs[0]->getType();
- F.ZeroExtendBaseReg = true;
- F.BaseRegs[0] = S;
-
- if (isLegalUse(TTI, LU.MinOffset, LU.MaxOffset, LU.Kind, LU.AccessTy, F))
- InsertFormula(LU, LUIdx, F);
- }
-}
-
namespace {
/// WorkItem - Helper class for GenerateCrossUseConstantOffsets. It's used to
@@ -3926,8 +3846,6 @@ LSRInstance::GenerateAllReuseFormulae()
LSRUse &LU = Uses[LUIdx];
for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
GenerateTruncates(LU, LUIdx, LU.Formulae[i]);
- for (size_t i = 0, f = LU.Formulae.size(); i != f; ++i)
- GenerateZExts(LU, LUIdx, LU.Formulae[i]);
}
GenerateCrossUseConstantOffsets();
@@ -4565,28 +4483,13 @@ Value *LSRInstance::Expand(const LSRFixu
// If we're expanding for a post-inc user, make the post-inc adjustment.
PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);
- const SCEV *ExtendedReg =
- F.ZeroExtendBaseReg ? SE.getZeroExtendExpr(Reg, F.ZeroExtendType) : Reg;
+ Reg = TransformForPostIncUse(Denormalize, Reg,
+ LF.UserInst, LF.OperandValToReplace,
+ Loops, SE, DT);
- const SCEV *PostIncReg =
- TransformForPostIncUse(Denormalize, ExtendedReg, LF.UserInst,
- LF.OperandValToReplace, Loops, SE, DT);
- if (PostIncReg == ExtendedReg) {
- Value *Expanded = Rewriter.expandCodeFor(Reg, nullptr, IP);
- if (F.ZeroExtendBaseReg)
- Expanded = new ZExtInst(Expanded, F.ZeroExtendType, "", IP);
- Ops.push_back(SE.getUnknown(Expanded));
- } else {
- Ops.push_back(
- SE.getUnknown(Rewriter.expandCodeFor(PostIncReg, nullptr, IP)));
- }
+ Ops.push_back(SE.getUnknown(Rewriter.expandCodeFor(Reg, nullptr, IP)));
}
- // Note on post-inc uses and zero extends -- since the no-wrap behavior for
- // the post-inc SCEV can be different from the no-wrap behavior of the pre-inc
- // SCEV, if a post-inc transform is required we do the zero extension on the
- // pre-inc expression before doing the post-inc transform.
-
// Expand the ScaledReg portion.
Value *ICmpScaledV = nullptr;
if (F.Scale != 0) {
@@ -4594,33 +4497,22 @@ Value *LSRInstance::Expand(const LSRFixu
// If we're expanding for a post-inc user, make the post-inc adjustment.
PostIncLoopSet &Loops = const_cast<PostIncLoopSet &>(LF.PostIncLoops);
- const SCEV *ExtendedScaleS =
- F.ZeroExtendScaledReg ? SE.getZeroExtendExpr(ScaledS, F.ZeroExtendType)
- : ScaledS;
- const SCEV *PostIncScaleS =
- TransformForPostIncUse(Denormalize, ExtendedScaleS, LF.UserInst,
- LF.OperandValToReplace, Loops, SE, DT);
+ ScaledS = TransformForPostIncUse(Denormalize, ScaledS,
+ LF.UserInst, LF.OperandValToReplace,
+ Loops, SE, DT);
if (LU.Kind == LSRUse::ICmpZero) {
// Expand ScaleReg as if it was part of the base regs.
- Value *Expanded = nullptr;
- if (PostIncScaleS == ExtendedScaleS) {
- Expanded = Rewriter.expandCodeFor(ScaledS, nullptr, IP);
- if (F.ZeroExtendScaledReg)
- Expanded = new ZExtInst(Expanded, F.ZeroExtendType, "", IP);
- } else {
- Expanded = Rewriter.expandCodeFor(PostIncScaleS, nullptr, IP);
- }
-
if (F.Scale == 1)
- Ops.push_back(SE.getUnknown(Expanded));
+ Ops.push_back(
+ SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP)));
else {
// An interesting way of "folding" with an icmp is to use a negated
// scale, which we'll implement by inserting it into the other operand
// of the icmp.
assert(F.Scale == -1 &&
"The only scale supported by ICmpZero uses is -1!");
- ICmpScaledV = Expanded;
+ ICmpScaledV = Rewriter.expandCodeFor(ScaledS, nullptr, IP);
}
} else {
// Otherwise just expand the scaled register and an explicit scale,
@@ -4634,17 +4526,7 @@ Value *LSRInstance::Expand(const LSRFixu
Ops.clear();
Ops.push_back(SE.getUnknown(FullV));
}
-
- Value *Expanded = nullptr;
- if (PostIncScaleS == ExtendedScaleS) {
- Expanded = Rewriter.expandCodeFor(ScaledS, nullptr, IP);
- if (F.ZeroExtendScaledReg)
- Expanded = new ZExtInst(Expanded, F.ZeroExtendType, "", IP);
- } else {
- Expanded = Rewriter.expandCodeFor(PostIncScaleS, nullptr, IP);
- }
-
- ScaledS = SE.getUnknown(Expanded);
+ ScaledS = SE.getUnknown(Rewriter.expandCodeFor(ScaledS, nullptr, IP));
if (F.Scale != 1)
ScaledS =
SE.getMulExpr(ScaledS, SE.getConstant(ScaledS->getType(), F.Scale));
Removed: llvm/trunk/test/Transforms/LoopStrengthReduce/X86/zext-of-scale.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopStrengthReduce/X86/zext-of-scale.ll?rev=243938&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopStrengthReduce/X86/zext-of-scale.ll (original)
+++ llvm/trunk/test/Transforms/LoopStrengthReduce/X86/zext-of-scale.ll (removed)
@@ -1,70 +0,0 @@
-; RUN: opt < %s -S -loop-reduce | FileCheck %s
-
-target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-unknown-linux-gnu"
-
-%struct = type { [8 x i8] }
-
-declare void @use_32(i32)
-declare void @use_64(i64)
-
-define void @f(i32 %tmp156, i32* %length_buf_1, i32* %length_buf_0, %struct* %b,
- %struct* %c, %struct* %d, %struct* %e, i32* %length_buf_2,
- i32 %tmp160) {
-; CHECK-LABEL: @f(
-entry:
- %begin151 = getelementptr inbounds %struct, %struct* %b, i64 0, i32 0, i64 12
- %tmp21 = bitcast i8* %begin151 to i32*
- %begin157 = getelementptr inbounds %struct, %struct* %c, i64 0, i32 0, i64 16
- %tmp23 = bitcast i8* %begin157 to double*
- %begin163 = getelementptr inbounds %struct, %struct* %d, i64 0, i32 0, i64 16
- %tmp25 = bitcast i8* %begin163 to double*
- %length.i820 = load i32, i32* %length_buf_1, align 4, !range !0
- %enter = icmp ne i32 %tmp156, -1
- br i1 %enter, label %ok_146, label %block_81_2
-
-ok_146:
- %var_13 = phi double [ %tmp186, %ok_161 ], [ 0.000000e+00, %entry ]
- %var_17 = phi i32 [ %tmp187, %ok_161 ], [ %tmp156, %entry ]
- %tmp174 = zext i32 %var_17 to i64
- %tmp175 = icmp ult i32 %var_17, %length.i820
- br i1 %tmp175, label %ok_152, label %block_81_2
-
-ok_152:
- %tmp176 = getelementptr inbounds i32, i32* %tmp21, i64 %tmp174
- %tmp177 = load i32, i32* %tmp176, align 4
- %tmp178 = zext i32 %tmp177 to i64
- %length.i836 = load i32, i32* %length_buf_2, align 4, !range !0
- %tmp179 = icmp ult i32 %tmp177, %length.i836
- br i1 %tmp179, label %ok_158, label %block_81_2
-
-ok_158:
- %tmp180 = getelementptr inbounds double, double* %tmp23, i64 %tmp178
- %tmp181 = load double, double* %tmp180, align 8
- %length.i = load i32, i32* %length_buf_0, align 4, !range !0
- %tmp182 = icmp slt i32 %var_17, %length.i
- br i1 %tmp182, label %ok_161, label %block_81_2
-
-ok_161:
-; CHECK-LABEL: ok_161:
-; CHECK: add
-; CHECK-NOT: add
- %tmp183 = getelementptr inbounds double, double* %tmp25, i64 %tmp174
- %tmp184 = load double, double* %tmp183, align 8
- %tmp185 = fmul double %tmp181, %tmp184
- %tmp186 = fadd double %var_13, %tmp185
- %tmp187 = add nsw i32 %var_17, 1
- %tmp188 = icmp slt i32 %tmp187, %tmp160
-; CHECK: br
- br i1 %tmp188, label %ok_146, label %block_81
-
-block_81:
- call void @use_64(i64 %tmp174) ;; pre-inc use
- call void @use_32(i32 %tmp187) ;; post-inc use
- ret void
-
-block_81_2:
- ret void
-}
-
-!0 = !{i32 0, i32 2147483647}
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