Re-commit : [PowerPC] Add handling for ColdCC calling convention and a pass to mark

candidates with coldcc attribute.

This recommits r322721 reverted due to sanitizer memory leak build bot failures.

Original commit message:
This patch adds support for the coldcc calling convention for Power.
This changes the set of non-volatile registers. It includes a pass to stress
test the implementation by marking all static directly called functions with
the coldcc attribute through the option -enable-coldcc-stress-test. It also
includes an option, -ppc-enable-coldcc, to add the coldcc attribute to
functions which are cold at all call sites based on BlockFrequencyInfo when
the containing function does not call any non cold functions.

Differential Revision: https://reviews.llvm.org/D38413

llvm-svn: 323778

1 files changed, 13 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
index aa4073f7ea0..226c75f704f 100644
--- a/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCTargetTransformInfo.cpp
@@ -27,6 +27,11 @@ static cl::opt<unsigned>
 CacheLineSize("ppc-loop-prefetch-cache-line", cl::Hidden, cl::init(64),
               cl::desc("The loop prefetch cache line size"));
 
+static cl::opt<bool>
+EnablePPCColdCC("ppc-enable-coldcc", cl::Hidden, cl::init(false),
+                cl::desc("Enable using coldcc calling conv for cold "
+                         "internal functions"));
+
 //===----------------------------------------------------------------------===//
 //
 // PPC cost model.
@@ -215,6 +220,14 @@ void PPCTTIImpl::getUnrollingPreferences(Loop *L, ScalarEvolution &SE,
   BaseT::getUnrollingPreferences(L, SE, UP);
 }
 
+// This function returns true to allow using coldcc calling convention.
+// Returning true results in coldcc being used for functions which are cold at
+// all call sites when the callers of the functions are not calling any other
+// non coldcc functions.
+bool PPCTTIImpl::useColdCCForColdCall(Function &F) {
+  return EnablePPCColdCC;
+}
+
 bool PPCTTIImpl::enableAggressiveInterleaving(bool LoopHasReductions) {
   // On the A2, always unroll aggressively. For QPX unaligned loads, we depend
   // on combining the loads generated for consecutive accesses, and failure to