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[X86] Add support for using fast short rep mov for memcpy lowering. 

Disabled by default behind an option.

Differential Revision: https://reviews.llvm.org/D86883
This commit is contained in:
Hiroshi Yamauchi 2020-08-21 12:44:36 -07:00
parent 72e2fbde54
commit 0ab6a15698
3 changed files with 40 additions and 1 deletions
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2
llvm/lib/Target/X86/X86ISelLowering.cpp
View File

@ -3109,7 +3109,7 @@ argsAreStructReturn(ArrayRef<ISD::InputArg> Ins, bool IsMCU) {
static SDValue CreateCopyOfByValArgument(SDValue Src, SDValue Dst,
SDValue Chain, ISD::ArgFlagsTy Flags,
SelectionDAG &DAG, const SDLoc &dl) {
SDValue SizeNode = DAG.getConstant(Flags.getByValSize(), dl, MVT::i32);
SDValue SizeNode = DAG.getIntPtrConstant(Flags.getByValSize(), dl);
return DAG.getMemcpy(
Chain, dl, Dst, Src, SizeNode, Flags.getNonZeroByValAlign(),

8
llvm/lib/Target/X86/X86SelectionDAGInfo.cpp
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@ -24,6 +24,10 @@ using namespace llvm;
#define DEBUG_TYPE "x86-selectiondag-info"
static cl::opt<bool>
UseFSRMForMemcpy("x86-use-fsrm-for-memcpy", cl::Hidden, cl::init(false),
cl::desc("Use fast short rep mov in memcpy lowering"));
bool X86SelectionDAGInfo::isBaseRegConflictPossible(
SelectionDAG &DAG, ArrayRef<MCPhysReg> ClobberSet) const {
// We cannot use TRI->hasBasePointer() until *after* we select all basic
@ -306,6 +310,10 @@ SDValue X86SelectionDAGInfo::EmitTargetCodeForMemcpy(
const X86Subtarget &Subtarget =
DAG.getMachineFunction().getSubtarget<X86Subtarget>();
// If enabled and available, use fast short rep mov.
if (UseFSRMForMemcpy && Subtarget.hasFSRM())
return emitRepmovs(Subtarget, DAG, dl, Chain, Dst, Src, Size, MVT::i8);
/// Handle constant sizes,
if (ConstantSDNode *ConstantSize = dyn_cast<ConstantSDNode>(Size))
return emitConstantSizeRepmov(

31
llvm/test/CodeGen/X86/memcpy-inline-fsrm.ll Normal file
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@ -0,0 +1,31 @@
; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
; RUN: llc -mtriple=x86_64-linux-gnu -x86-use-fsrm-for-memcpy -mattr=-fsrm < %s -o - | FileCheck %s --check-prefix=NOFSRM
; RUN: llc -mtriple=x86_64-linux-gnu -x86-use-fsrm-for-memcpy -mattr=+fsrm < %s -o - | FileCheck %s --check-prefix=FSRM
; RUN: llc -mtriple=x86_64-linux-gnu -x86-use-fsrm-for-memcpy -mcpu=haswell < %s | FileCheck %s --check-prefix=NOFSRM
; RUN: llc -mtriple=x86_64-linux-gnu -x86-use-fsrm-for-memcpy -mcpu=icelake-client < %s | FileCheck %s --check-prefix=FSRM
; RUN: llc -mtriple=x86_64-linux-gnu -x86-use-fsrm-for-memcpy -mcpu=icelake-server < %s | FileCheck %s --check-prefix=FSRM
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i1) nounwind
define void @test1(i8* %a, i8* %b, i64 %s) nounwind {
; NOFSRM-LABEL: test1
; NOFSRM: # %bb.0:
; NOFSRM: jmp memcpy
;
; FSRM-LABEL: test1
; FSRM: # %bb.0:
; FSRM-NEXT: movq %rdx, %rcx
; FSRM-NEXT: rep;movsb (%rsi), %es:(%rdi)
; FSRM-NEXT: retq
tail call void @llvm.memcpy.p0i8.p0i8.i64(i8* %a, i8* %b, i64 %s, i1 0)
ret void
}
; Check that we don't crash due to a memcpy size type mismatch error ("Cannot
; emit physreg copy instruction") in X86InstrInfo::copyPhysReg.
%struct = type { [4096 x i8] }
declare void @foo(%struct* byval)
define void @test2(%struct* %x) {
call void @foo(%struct* byval %x)
ret void
}