3 Commits

Author SHA1 Message Date
Craig Topper
3fe4bd464c [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

llvm-svn: 354756
2019-02-24 19:33:37 +00:00
Reid Kleckner
49a24278ba [ELF] Fix large code model MIR verifier errors
Instead of using the MOVGOT64r pseudo, use the existing
MO_PIC_BASE_OFFSET support on symbol operands. Now I don't have to
create a "scratch register operand" for the pseudo to use, and the
register allocator can make better decisions.

Fixes some X86 verifier errors tracked in PR27481.

llvm-svn: 345219
2018-10-24 22:57:28 +00:00
Reid Kleckner
980c4df037 Re-land r335297 "[X86] Implement more of x86-64 large and medium PIC code models"
Don't try to generate large PIC code for non-ELF targets. Neither COFF
nor MachO have relocations for large position independent code, and
users have been using "large PIC" code models to JIT 64-bit code for a
while now. With this change, if they are generating ELF code, their
JITed code will truly be PIC, but if they target MachO or COFF, it will
contain 64-bit immediates that directly reference external symbols. For
a JIT, that's perfectly fine.

llvm-svn: 337740
2018-07-23 21:14:35 +00:00