Fix crash in AggressiveAntiDepBreaker with empty CriticalPathSet

If no register classes are added to CriticalPathRCs, then the CriticalPathSet
bitmask will be empty. In that case, ExcludeRegs must remain NULL or else this
line will cause a segfault:

  } else if ((ExcludeRegs != NULL) && ExcludeRegs->test(AntiDepReg)) {

I have no in-tree test case.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190584 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AggressiveAntiDepBreaker.cpp b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
index e0797079c5eb1b51bbbba9034c94da4619cdb2a7..2ee7767115875b1fce6d9d9872340c8f6b8c783d 100644 (file)
--- a/lib/CodeGen/AggressiveAntiDepBreaker.cpp
+++ b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
@@ -782,7 +782,7 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
     if (MI == CriticalPathMI) {
       CriticalPathSU = CriticalPathStep(CriticalPathSU);
       CriticalPathMI = (CriticalPathSU) ? CriticalPathSU->getInstr() : 0;
-    } else {
+    } else if (CriticalPathSet.any()) {
       ExcludeRegs = &CriticalPathSet;
     }