[llvm-commits] CVS: llvm/lib/Transforms/Scalar/InstructionCombining.cpp

[Chris Lattner]

Changes in directory llvm/lib/Transforms/Scalar:

InstructionCombining.cpp updated: 1.415 -> 1.416
---
Log message:

Implement casts.ll:test26: a cast from float -> double -> integer, doesn't
need the float->double part.


---
Diffs of the changes:  (+11 -2)

 InstructionCombining.cpp |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)


Index: llvm/lib/Transforms/Scalar/InstructionCombining.cpp
diff -u llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.415 llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.416
--- llvm/lib/Transforms/Scalar/InstructionCombining.cpp:1.415	Mon Jan 16 13:47:21 2006
+++ llvm/lib/Transforms/Scalar/InstructionCombining.cpp	Thu Jan 19 01:40:22 2006
@@ -3799,8 +3799,8 @@
 // isEliminableCastOfCast - Return true if it is valid to eliminate the CI
 // instruction.
 //
-static inline bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
-                                          const Type *DstTy, TargetData *TD) {
+static bool isEliminableCastOfCast(const Type *SrcTy, const Type *MidTy,
+                                   const Type *DstTy, TargetData *TD) {
 
   // It is legal to eliminate the instruction if casting A->B->A if the sizes
   // are identical and the bits don't get reinterpreted (for example
@@ -3856,6 +3856,15 @@
       return ResultCast == FirstCast;
     }
   }
+  
+  // If this is a cast from 'float -> double -> integer', cast from
+  // 'float -> integer' directly, as the value isn't changed by the 
+  // float->double conversion.
+  if (SrcTy->isFloatingPoint() && MidTy->isFloatingPoint() &&
+      DstTy->isIntegral() && 
+      SrcTy->getPrimitiveSize() < MidTy->getPrimitiveSize())
+    return true;
+  
   return false;
 }