[llvm-commits] [llvm] r85478 - /llvm/trunk/lib/Analysis/MemoryBuiltins.cpp

[Victor Hernandez]

Duncan,

Here's my patch to get rid of doubles, how does it look?

Index: lib/Analysis/MemoryBuiltins.cpp
===================================================================
--- lib/Analysis/MemoryBuiltins.cpp	(revision 85528)
+++ lib/Analysis/MemoryBuiltins.cpp	(working copy)
@@ -158,13 +158,19 @@
      if (Opcode == Instruction::Shl) {
        ConstantInt* Op1Int = dyn_cast<ConstantInt>(Op1);
        if (!Op1Int) return NULL;
-      Value* Op1Pow = ConstantInt::get(Op1->getType(),
-                                    pow(2.0, (double) Op1Int- 
 >getZExtValue()));
+
+      unsigned Op1BitWidth = Op1->getType()->getPrimitiveSizeInBits();
+      // check for overflow
+      if (Op1Int->getZExtValue() > Op1BitWidth)
+        return NULL;
+
+      Value* Op1Pow = ConstantInt::get(Context,
+                            APInt(Op1BitWidth, 1, false) << Op1Int- 
 >getValue());
        if (Op0 == ElementSize || (FoldedElementSize && Op0 ==  
FoldedElementSize))
          // ArraySize << log2(ElementSize)
          return Op1Pow;
        if (Op1Pow == ElementSize ||
-        (FoldedElementSize && Op1Pow == FoldedElementSize))
+          (FoldedElementSize && Op1Pow == FoldedElementSize))
          // ElementSize << log2(ArraySize)
          return Op0;
      }

thanks,
Victor

On Oct 29, 2009, at 1:26 AM, Duncan Sands wrote:

> Hi,
>
>>       ConstantInt* Op1Int = dyn_cast<ConstantInt>(Op1);
>>       if (!Op1Int) return NULL;
>>       Value* Op1Pow = ConstantInt::get(Op1->getType(),
>> -                                       pow(2, Op1Int->getZExtValue 
>> ()));
>> +                                       pow((double) 2, (double)  
>> Op1Int->getZExtValue()));
>
> this is an integer power: 2 to the power of Op1Int.  This shouldn't  
> be done like
> this at all!  It's just a shift left for heavens sake - why the  
> doubles?!  It
> can other be done in uint64_t, or using the APInt shift methods.
>
> /me makes note to self to audit this code for other monstrosities.
>
> Ciao,
>
> Duncan.
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