[PowerPC] Do not produce invalid CTR loop with an FRem

An FRem instruction inside a loop should prevent the loop from being converted
into a CTR loop since this is not an operation that is legal on any PPC
subtarget. This will always be a call to a library function which means the
loop will be invalid if this instruction is in the body.

Fixes PR36292.

llvm-svn: 325739

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp b/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp
index ae9b8c518d5..6443447e70c 100644
--- a/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp
+++ b/llvm/lib/Target/PowerPC/PPCCTRLoops.cpp
@@ -455,13 +455,16 @@ bool PPCCTRLoops::mightUseCTR(BasicBlock *BB) {
         return true;
     }
 
+    // FREM is always a call.
+    if (J->getOpcode() == Instruction::FRem)
+      return true;
+
     if (STI->useSoftFloat()) {
       switch(J->getOpcode()) {
       case Instruction::FAdd:
       case Instruction::FSub:
       case Instruction::FMul:
       case Instruction::FDiv:
-      case Instruction::FRem:
       case Instruction::FPTrunc:
       case Instruction::FPExt:
       case Instruction::FPToUI: