Merging r343443:

------------------------------------------------------------------------
r343443 | ctopper | 2018-10-01 00:08:41 -0700 (Mon, 01 Oct 2018) | 9 lines

[X86] Stop X86DomainReassignment from creating copies between GR8/GR16 physical registers and k-registers.

We can only copy between a k-register and a GR32/GR64 register.

This patch detects that the copy will be illegal and prevents the domain reassignment from happening for that closure.

This probably isn't the best fix, and we should probably figure out how to handle this correctly.

Fixes PR38803.
------------------------------------------------------------------------

llvm-svn: 344804

1 files changed, 21 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86DomainReassignment.cpp b/llvm/lib/Target/X86/X86DomainReassignment.cpp
index 5196446b39e..62588e9509d 100644
--- a/llvm/lib/Target/X86/X86DomainReassignment.cpp
+++ b/llvm/lib/Target/X86/X86DomainReassignment.cpp
@@ -217,6 +217,27 @@ public:
   InstrCOPYReplacer(unsigned SrcOpcode, RegDomain DstDomain, unsigned DstOpcode)
       : InstrReplacer(SrcOpcode, DstOpcode), DstDomain(DstDomain) {}
 
+  bool isLegal(const MachineInstr *MI,
+               const TargetInstrInfo *TII) const override {
+    if (!InstrConverterBase::isLegal(MI, TII))
+      return false;
+
+    // Don't allow copies to/flow GR8/GR16 physical registers.
+    // FIXME: Is there some better way to support this?
+    unsigned DstReg = MI->getOperand(0).getReg();
+    if (TargetRegisterInfo::isPhysicalRegister(DstReg) &&
+        (X86::GR8RegClass.contains(DstReg) ||
+         X86::GR16RegClass.contains(DstReg)))
+      return false;
+    unsigned SrcReg = MI->getOperand(1).getReg();
+    if (TargetRegisterInfo::isPhysicalRegister(SrcReg) &&
+        (X86::GR8RegClass.contains(SrcReg) ||
+         X86::GR16RegClass.contains(SrcReg)))
+      return false;
+
+    return true;
+  }
+
   double getExtraCost(const MachineInstr *MI,
                       MachineRegisterInfo *MRI) const override {
     assert(MI->getOpcode() == TargetOpcode::COPY && "Expected a COPY");