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Do not insert prefetches with unsupported memory operands.

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Summary:
Ignore advices where the memory operand of the 'anchor' instruction
uses unsupported register types.

Reviewers: davidxl

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D54983

llvm-svn: 347724
This commit is contained in:
Mircea Trofin 2018-11-28 01:08:45 +00:00
parent f3afb84186
commit 0953e7ad7b
3 changed files with 21 additions and 5 deletions
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20
lib/Target/X86/X86InsertPrefetch.cpp
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@ -76,6 +76,19 @@ ErrorOr<PrefetchHints> getPrefetchHints(const FunctionSamples *TopSamples,
return std::error_code();
}
// The prefetch instruction can't take memory operands involving vector
// registers.
bool IsMemOpCompatibleWithPrefetch(const MachineInstr &MI, int Op) {
unsigned BaseReg = MI.getOperand(Op + X86::AddrBaseReg).getReg();
unsigned IndexReg = MI.getOperand(Op + X86::AddrIndexReg).getReg();
return (BaseReg == 0 ||
X86MCRegisterClasses[X86::GR64RegClassID].contains(BaseReg) ||
X86MCRegisterClasses[X86::GR32RegClassID].contains(BaseReg)) &&
(IndexReg == 0 ||
X86MCRegisterClasses[X86::GR64RegClassID].contains(IndexReg) ||
X86MCRegisterClasses[X86::GR32RegClassID].contains(IndexReg));
}
} // end anonymous namespace
//===----------------------------------------------------------------------===//
@ -182,6 +195,11 @@ bool X86InsertPrefetch::runOnMachineFunction(MachineFunction &MF) {
int Offset = X86II::getMemoryOperandNo(Current->getDesc().TSFlags);
if (Offset < 0)
continue;
unsigned Bias = X86II::getOperandBias(Current->getDesc());
int MemOpOffset = Offset + Bias;
// FIXME(mtrofin): ORE message when the recommendation cannot be taken.
if (!IsMemOpCompatibleWithPrefetch(*Current, MemOpOffset))
continue;
Prefetches.clear();
if (!findPrefetchInfo(Samples, *Current, Prefetches))
continue;
@ -195,8 +213,6 @@ bool X86InsertPrefetch::runOnMachineFunction(MachineFunction &MF) {
MachineInstr *PFetch =
MF.CreateMachineInstr(Desc, Current->getDebugLoc(), true);
MachineInstrBuilder MIB(MF, PFetch);
unsigned Bias = X86II::getOperandBias(Current->getDesc());
int MemOpOffset = Offset + Bias;
assert(X86::AddrBaseReg == 0 && X86::AddrScaleAmt == 1 &&
X86::AddrIndexReg == 2 && X86::AddrDisp == 3 &&

0
test/CodeGen/X86/insert-prefetch-nomemop.afdo → test/CodeGen/X86/insert-prefetch-invalid-instr.afdo
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6
test/CodeGen/X86/insert-prefetch-no-MachineMemOperand.ll → test/CodeGen/X86/insert-prefetch-invalid-instr.ll
View File

@ -1,4 +1,4 @@
; RUN: llc < %s -prefetch-hints-file=%S/insert-prefetch-nomemop.afdo | FileCheck %s
; RUN: llc < %s -prefetch-hints-file=%S/insert-prefetch-invalid-instr.afdo | FileCheck %s
; ModuleID = 'prefetch.cc'
source_filename = "prefetch.cc"
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
@ -42,5 +42,5 @@ attributes #2 = { argmemonly nounwind }
;CHECK-LABEL: main:
;CHECK: # %bb.0:
;CHECK: prefetchnta 291
;CHECK: prefetchnta 42(%rax,%ymm0)
;CHECK-NEXT: vgatherpf1dpd (%rax,%ymm0) {%k1}
;CHECK-NOT: prefetchnta 42(%rax,%ymm0)
;CHECK: vgatherpf1dpd (%rax,%ymm0) {%k1}