[PowerPC] Replace float load/store pair with integer load/store pair when it's only used in load/store

Replace float load/store pair with integer load/store pair when it's only used in load/store,
because float load/store instructions cost more cycles then integer load/store.

A typical scenario is when there is a call with more than 13 float arguments passing, we need pass them by stack.
So we need a load/store pair to do such memory operation if the variable is global variable.

Differential Revision: https://reviews.llvm.org/D64195

llvm-svn: 366775

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.h b/llvm/lib/Target/PowerPC/PPCISelLowering.h
index 97422c6eda3..ff9423aadee 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.h
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.h
@@ -834,6 +834,18 @@ namespace llvm {
       return true;
     }
 
+    bool isDesirableToTransformToIntegerOp(unsigned Opc,
+                                           EVT VT) const override {
+      // Only handle float load/store pair because float(fpr) load/store
+      // instruction has more cycles than integer(gpr) load/store in PPC.
+      if (Opc != ISD::LOAD && Opc != ISD::STORE)
+        return false;
+      if (VT != MVT::f32 && VT != MVT::f64)
+        return false;
+
+      return true; 
+    }
+
     // Returns true if the address of the global is stored in TOC entry.
     bool isAccessedAsGotIndirect(SDValue N) const;