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Pull in r354756 from upstream llvm trunk (by Craig Topper):

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[X86] Fix tls variable lowering issue with large code model

  Summary:
  The problem here is the lowering for tls variable. Below is the DAG
  for the code. SelectionDAG has 11 nodes:

  t0: ch = EntryToken
	t8: i64,ch = load<(load 8 from `i8 addrspace(257)* null`,
	addrspace 257)> t0, Constant:i64<0>, undef:i64
	  t10: i64 = X86ISD::WrapperRIP TargetGlobalTLSAddress:i64<i32*
	  @x> 0 [TF=10]
	t11: i64,ch = load<(load 8 from got)> t0, t10, undef:i64
      t12: i64 = add t8, t11
    t4: i32,ch = load<(dereferenceable load 4 from @x)> t0, t12,
    undef:i64
  t6: ch = CopyToReg t0, Register:i32 %0, t4

  And when mcmodel is large, below instruction can NOT be folded.

    t10: i64 = X86ISD::WrapperRIP TargetGlobalTLSAddress:i64<i32* @x> 0
    [TF=10]
  t11: i64,ch = load<(load 8 from got)> t0, t10, undef:i64

  So "t11: i64,ch = load<(load 8 from got)> t0, t10, undef:i64" is
  lowered to " Morphed node: t11: i64,ch = MOV64rm<Mem:(load 8 from
  got)> t10, TargetConstant:i8<1>, Register:i64 $noreg,
  TargetConstant:i32<0>, Register:i32 $noreg, t0"

  When llvm start to lower "t10: i64 = X86ISD::WrapperRIP
  TargetGlobalTLSAddress:i64<i32* @x> 0 [TF=10]", it fails.

  The patch is to fold the load and X86ISD::WrapperRIP.

  Fixes PR26906

  Patch by LuoYuanke

  Reviewers: craig.topper, rnk, annita.zhang, wxiao3

  Reviewed By: rnk

  Subscribers: llvm-commits

  Tags: #llvm

  Differential Revision: https://reviews.llvm.org/D58336

This should fix "fatal error: error in backend: Cannot select" messages
when compiling <ctype.h> functions using -mcmodel=large.

Reported by:	phk
PR:		233143
MFC after:	3 days
This commit is contained in:
Dimitry Andric 2019-02-24 21:22:16 +00:00
parent 484160a9cf
commit 4f560b016f
1 changed files with 13 additions and 5 deletions
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18
contrib/llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
View file

@ -989,15 +989,23 @@ bool X86DAGToDAGISel::matchWrapper(SDValue N, X86ISelAddressMode &AM) {
if (AM.hasSymbolicDisplacement())
return true;
bool IsRIPRelTLS = false;
bool IsRIPRel = N.getOpcode() == X86ISD::WrapperRIP;
if (IsRIPRel) {
SDValue Val = N.getOperand(0);
if (Val.getOpcode() == ISD::TargetGlobalTLSAddress)
IsRIPRelTLS = true;
}
// We can't use an addressing mode in the 64-bit large code model. In the
// medium code model, we use can use an mode when RIP wrappers are present.
// That signifies access to globals that are known to be "near", such as the
// GOT itself.
// We can't use an addressing mode in the 64-bit large code model.
// Global TLS addressing is an exception. In the medium code model,
// we use can use a mode when RIP wrappers are present.
// That signifies access to globals that are known to be "near",
// such as the GOT itself.
CodeModel::Model M = TM.getCodeModel();
if (Subtarget->is64Bit() &&
(M == CodeModel::Large || (M == CodeModel::Medium && !IsRIPRel)))
((M == CodeModel::Large && !IsRIPRelTLS) ||
(M == CodeModel::Medium && !IsRIPRel)))
return true;
// Base and index reg must be 0 in order to use %rip as base.