[PowerPC][MC] Support expressions in getMemRIX16Encoding.

Loosens an assert in getMemRIX16Encoding that restricts DQ-form instructions to
using an immediate, so that we can assemble instructions like lxv/stxv where the
offset is an expression.

Differential Revision: https://reviews.llvm.org/D51122

llvm-svn: 340761

1 files changed, 9 insertions, 3 deletions

diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
index 57bda1403c6..5a0b35a571a 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCCodeEmitter.cpp
@@ -264,10 +264,16 @@ unsigned PPCMCCodeEmitter::getMemRIX16Encoding(const MCInst &MI, unsigned OpNo,
   unsigned RegBits = getMachineOpValue(MI, MI.getOperand(OpNo+1), Fixups, STI) << 12;
 
   const MCOperand &MO = MI.getOperand(OpNo);
-  assert(MO.isImm() && !(MO.getImm() % 16) &&
-         "Expecting an immediate that is a multiple of 16");
+  if (MO.isImm()) {
+    assert(!(MO.getImm() % 16) &&
+           "Expecting an immediate that is a multiple of 16");
+    return ((getMachineOpValue(MI, MO, Fixups, STI) >> 4) & 0xFFF) | RegBits;
+  }
 
-  return ((getMachineOpValue(MI, MO, Fixups, STI) >> 4) & 0xFFF) | RegBits;
+  // Otherwise add a fixup for the displacement field.
+  Fixups.push_back(MCFixup::create(IsLittleEndian? 0 : 2, MO.getExpr(),
+                                   (MCFixupKind)PPC::fixup_ppc_half16ds));
+  return RegBits;
 }
 
 unsigned PPCMCCodeEmitter::getSPE8DisEncoding(const MCInst &MI, unsigned OpNo,