Cache subregister relationships in a set in TargetRegisterInfo to allow faster lookups.

This speeds up LiveVariables from 0.6279s to 0.6165s on kimwitu++.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52818 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 10 insertions, 0 deletions

diff --git a/lib/Target/TargetRegisterInfo.cpp b/lib/Target/TargetRegisterInfo.cpp
index 3f44a0cb5a..e69496f4b2 100644
--- a/lib/Target/TargetRegisterInfo.cpp
+++ b/lib/Target/TargetRegisterInfo.cpp
@@ -29,6 +29,16 @@ TargetRegisterInfo::TargetRegisterInfo(const TargetRegisterDesc *D, unsigned NR,
 
   CallFrameSetupOpcode   = CFSO;
   CallFrameDestroyOpcode = CFDO;
+  
+  for (unsigned i = 0; i < NumRegs; ++i) {
+    const TargetRegisterDesc* CurrReg = Desc + i;
+    
+    // Initialize the Subregs set, which stores pairs (a, b) where
+    // b is a subreg of a.
+    if (CurrReg->SubRegs)
+      for (const unsigned* CurrSR = CurrReg->SubRegs; *CurrSR; ++CurrSR)
+        Subregs.insert(std::make_pair(i, *CurrSR));
+  }
 }
 
 TargetRegisterInfo::~TargetRegisterInfo() {}