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[X86] Disable loop unrolling in loop vectorization pass when VF is 1.

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The patch disabled unrolling in loop vectorization pass when VF==1 on x86 architecture,
by setting MaxInterleaveFactor to 1. Unrolling in loop vectorization pass may introduce
the cost of overflow check, memory boundary check and extra prologue/epilogue code when
regular unroller will unroll the loop another time. Disable it when VF==1 remove the
unnecessary cost on x86. The same can be done for other platforms after verifying
interleaving/memory bound checking to be not perf critical on those platforms.

Differential Revision: http://reviews.llvm.org/D9515


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236613 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Wei Mi
2015-05-06 17:12:25 +00:00
parent 530a574a9d
commit cac51be31f
16 changed files with 64 additions and 19 deletions
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8
include/llvm/Analysis/TargetTransformInfo.h
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@ -403,7 +403,7 @@ public:
/// \return The maximum interleave factor that any transform should try to
/// perform for this target. This number depends on the level of parallelism
/// and the number of execution units in the CPU.
unsigned getMaxInterleaveFactor() const;
unsigned getMaxInterleaveFactor(unsigned VF) const;
/// \return The expected cost of arithmetic ops, such as mul, xor, fsub, etc.
unsigned
@ -562,7 +562,7 @@ public:
const APInt &Imm, Type *Ty) = 0;
virtual unsigned getNumberOfRegisters(bool Vector) = 0;
virtual unsigned getRegisterBitWidth(bool Vector) = 0;
virtual unsigned getMaxInterleaveFactor() = 0;
virtual unsigned getMaxInterleaveFactor(unsigned VF) = 0;
virtual unsigned
getArithmeticInstrCost(unsigned Opcode, Type *Ty, OperandValueKind Opd1Info,
OperandValueKind Opd2Info,
@ -703,8 +703,8 @@ public:
unsigned getRegisterBitWidth(bool Vector) override {
return Impl.getRegisterBitWidth(Vector);
}
unsigned getMaxInterleaveFactor() override {
return Impl.getMaxInterleaveFactor();
unsigned getMaxInterleaveFactor(unsigned VF) override {
return Impl.getMaxInterleaveFactor(VF);
}
unsigned
getArithmeticInstrCost(unsigned Opcode, Type *Ty, OperandValueKind Opd1Info,