[llvm-profgen] Turn off cold context trimming by default

[wenlei]

Summary

We merge cold context by default to save profile size. However trimming cold context after merging doesn't save size much, so default to off to reflect how it's commonly used.

[hoy]

lgtm.

llvm/tools/llvm-profgen/ProfileGenerator.cpp

 
 static cl::opt<bool> CSProfMergeColdContext(
     "csprof-merge-cold-context", cl::init(true), cl::ZeroOrMore,
     cl::desc("If the total count of context profile is smaller than "
              "the threshold, it will be merged into context-less base "
              "profile."));
 
 static cl::opt<bool> CSProfTrimColdContext(
-    "csprof-trim-cold-context", cl::init(true), cl::ZeroOrMore,
+    "csprof-trim-cold-context", cl::init(false), cl::ZeroOrMore,
     cl::desc("If the total count of the profile after all merge is done "
              "is still smaller than threshold, it will be trimmed."));
 
 static cl::opt<uint32_t> CSProfMaxColdContextDepth(
     "csprof-max-cold-context-depth", cl::init(1), cl::ZeroOrMore,
     cl::desc("Keep the last K contexts while merging cold profile. 1 means the "
              "context-less base profile"));