[PPC64] Fix PR20071 (fctiduz generated for targets lacking that instruction)

PR20071 identifies a problem in PowerPC's fast-isel implementation for
floating-point conversion to integer.  The fctiduz instruction was added in
Power ISA 2.06 (i.e., Power7 and later).  However, this instruction is being
generated regardless of which 64-bit PowerPC target is selected.

The intent is for fast-isel to punt to DAG selection when this instruction is
not available.  This patch implements that change.  For testing purposes, the
existing fast-isel-conversion.ll test adds a RUN line for -mcpu=970 and tests
for the expected code generation.  Additionally, the existing test
fast-isel-conversion-p5.ll was found to be incorrectly expecting the
unavailable instruction to be generated.  I've removed these test variants
since we have adequate coverage in fast-isel-conversion.ll.

llvm-svn: 211627

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCFastISel.cpp b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
index f3730e74c1d..92a0ec1a9b3 100644
--- a/llvm/lib/Target/PowerPC/PPCFastISel.cpp
+++ b/llvm/lib/Target/PowerPC/PPCFastISel.cpp
@@ -1030,6 +1030,10 @@ bool PPCFastISel::SelectFPToI(const Instruction *I, bool IsSigned) {
   if (DstVT != MVT::i32 && DstVT != MVT::i64)
     return false;
 
+  // If we don't have FCTIDUZ and we need it, punt to SelectionDAG.
+  if (DstVT == MVT::i64 && !IsSigned && !PPCSubTarget->hasFPCVT())
+    return false;
+
   Value *Src = I->getOperand(0);
   Type *SrcTy = Src->getType();
   if (!isTypeLegal(SrcTy, SrcVT))