Remove the MCRegAliasIterator tables and compute the aliases dynamically.

The size reduction in the RegDiffLists are rather dramatic.  Here are a few
size differences for MCTargetDesc.o files (before and after) in bytes:
R600 - 36160B - 11184B - 69% reduction
ARM - 28480B - 8368B - 71% reduction
Mips - 816B - 576B - 29% reduction

One side effect of dynamically computing the aliases is that the iterator does
not guarantee that the entries are ordered or that duplicates have been removed.
The documentation implies this is a safe assumption and I found no clients that
requires these attributes (i.e., strict ordering and uniqueness).

My local LNT tester results showed no execution-time failures or significant
compile-time regressions (i.e., beyond what I would consider noise) for -O0g,
-O2 and -O3 runs on x86_64 and i386 configurations.
rdar://12906217

llvm-svn: 182783

1 files changed, 0 insertions, 3 deletions

diff --git a/llvm/utils/TableGen/CodeGenRegisters.h b/llvm/utils/TableGen/CodeGenRegisters.h
index b56555dade6..ba62db48274 100644
--- a/llvm/utils/TableGen/CodeGenRegisters.h
+++ b/llvm/utils/TableGen/CodeGenRegisters.h
@@ -205,9 +205,6 @@ namespace llvm {
     // Canonically ordered set.
     typedef std::set<const CodeGenRegister*, Less> Set;
 
-    // Compute the set of registers overlapping this.
-    void computeOverlaps(Set &Overlaps, const CodeGenRegBank&) const;
-
   private:
     bool SubRegsComplete;
     bool SuperRegsComplete;