Add pthread_self function prototype and make it speculatable.

Summary: This allows pthread_self to be pulled out of a loop by LICM.

Reviewers: hfinkel, arsenm, davide

Reviewed By: davide

Subscribers: davide, wdng, llvm-commits

Differential Revision: https://reviews.llvm.org/D32782

llvm-svn: 303495

1 files changed, 12 insertions, 0 deletions

diff --git a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
index ebde1f9a17d..cf345325254 100644
--- a/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
+++ b/llvm/lib/Transforms/Utils/BuildLibCalls.cpp
@@ -38,6 +38,7 @@ STATISTIC(NumNoCapture, "Number of arguments inferred as nocapture");
 STATISTIC(NumReadOnlyArg, "Number of arguments inferred as readonly");
 STATISTIC(NumNoAlias, "Number of function returns inferred as noalias");
 STATISTIC(NumNonNull, "Number of function returns inferred as nonnull returns");
+STATISTIC(NumSpeculatable, "Number of functions inferred as speculatable");
 
 static bool setDoesNotAccessMemory(Function &F) {
   if (F.doesNotAccessMemory())
@@ -71,6 +72,14 @@ static bool setDoesNotThrow(Function &F) {
   return true;
 }
 
+static bool setSpeculatable(Function &F) {
+  if (F.isSpeculatable())
+    return false;
+  F.setSpeculatable();
+  ++NumSpeculatable;
+  return true;
+}
+
 static bool setRetDoesNotAlias(Function &F) {
   if (F.hasAttribute(AttributeList::ReturnIndex, Attribute::NoAlias))
     return false;
@@ -530,6 +539,9 @@ bool llvm::inferLibFuncAttributes(Function &F, const TargetLibraryInfo &TLI) {
     Changed |= setOnlyReadsMemory(F, 0);
     Changed |= setOnlyReadsMemory(F, 1);
     return Changed;
+  case LibFunc_pthread_self:
+    Changed |= setSpeculatable(F);
+    return Changed;
   case LibFunc_vfscanf:
     Changed |= setDoesNotThrow(F);
     Changed |= setDoesNotCapture(F, 0);