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[X86] Preserve memory refs when folding loads into divides. 

This is similar to what we already do for multiplies. Without this we can't unfold and hoist an invariant load.

llvm-svn: 317732
This commit is contained in:
Craig Topper 2017-11-08 22:26:39 +00:00
parent 55029d811f
commit 61f81f9637
2 changed files with 34 additions and 2 deletions
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6
llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
View File

@ -2885,11 +2885,15 @@ void X86DAGToDAGISel::Select(SDNode *Node) {
if (foldedLoad) {
SDValue Ops[] = { Tmp0, Tmp1, Tmp2, Tmp3, Tmp4, N1.getOperand(0),
InFlag };
SDNode *CNode =
MachineSDNode *CNode =
CurDAG->getMachineNode(MOpc, dl, MVT::Other, MVT::Glue, Ops);
InFlag = SDValue(CNode, 1);
// Update the chain.
ReplaceUses(N1.getValue(1), SDValue(CNode, 0));
// Record the mem-refs
MachineSDNode::mmo_iterator MemOp = MF->allocateMemRefsArray(1);
MemOp[0] = cast<LoadSDNode>(N1)->getMemOperand();
CNode->setMemRefs(MemOp, MemOp + 1);
} else {
InFlag =
SDValue(CurDAG->getMachineNode(Opc, dl, MVT::Glue, N1, InFlag), 0);

30
llvm/test/CodeGen/X86/hoist-invariant-load.ll
View File

@ -1,10 +1,12 @@
; REQUIRES: asserts
; RUN: llc -mcpu=haswell < %s -stats -O2 2>&1 | grep "4 machinelicm.*hoisted"
; RUN: llc -mcpu=haswell < %s -stats -O2 2>&1 | grep "7 machinelicm.*hoisted"
; For test:
; 2 invariant loads, 1 for OBJC_SELECTOR_REFERENCES_
; and 1 for objc_msgSend from the GOT
; For test_multi_def:
; 2 invariant load (full multiply, both loads should be hoisted.)
; For test_div_def:
; 2 invariant load (full divide, both loads should be hoisted.) 1 additional instruction for a zeroing edx that gets hoisted and then rematerialized.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.7.2"
@ -60,4 +62,30 @@ exit:
ret void
}
define void @test_div_def(i32* dereferenceable(8) %x1,
i32* dereferenceable(8) %x2,
i32* %y, i32 %count) nounwind {
entry:
br label %for.body
for.check:
%inc = add nsw i32 %i, 1
%done = icmp sge i32 %inc, %count
br i1 %done, label %exit, label %for.body
for.body:
%i = phi i32 [ 0, %entry ], [ %inc, %for.check ]
%x1_load = load i32, i32* %x1, align 8, !invariant.load !0
%x2_load = load i32, i32* %x2, align 8, !invariant.load !0
%x_quot = udiv i32 %x1_load, %x2_load
%y_elem = getelementptr inbounds i32, i32* %y, i32 %i
%y_load = load i32, i32* %y_elem, align 8
%y_plus = add i32 %x_quot, %y_load
store i32 %y_plus, i32* %y_elem, align 8
br label %for.check
exit:
ret void
}
!0 = !{}