[llvm-commits] [PATCH] Compress Repeated Byte Output

[Chris Lattner]

On Aug 25, 2011, at 1:43 PM, David Greene wrote:

> 
> Emit a repeated sequence of bytes using .zero.  This saves an enormous
> amount of asm file space for certain programs.
> ---
> 
> This patch fixed a bunch of problems we saw related to asm output file size.
> Please review.  Thanks!

Looks good with a few changes:

+static bool isRepeatedByteSequence(const ConstantInt *CI, TargetMachine &TM) {

This needs a doxygen comment, also please change it to be something like:

static int isRepeatedByteSequence(const Value *V, TargetMachine &TM) {

and have it return 0-255 for success and -1 for failure.  It should handle the non-ConstantInt case as well.  You could even generalize this predicate to handle structs and subarrays if you feel ambitious (but as a follow-on patch).

+  if (CI->isZero() ||
+      CI->isAllOnesValue() ||
+      TM.getTargetData()->getTypeAllocSize(CI->getType()) == 1)
+    return true;
+
+  unsigned Bytes = TM.getTargetData()->getTypeAllocSize(CI->getType());

Please don't call getTypeAllocSize twice, use:

+  if (CI->isZero() || CI->isAllOnesValue())
    return true;

+  unsigned Bytes = TM.getTargetData()->getTypeAllocSize(CI->getType());
  if (Bytes == 1) return true;
...


+  uint64_t Value = CI->getZExtValue();

This will abort for int128_t, please check that the bitwidth of CI is <= 64 bits and a multiple of 8 bits.

Please resend with this changes, thanks!

-Chris