[clang] ee8b538 - [BranchProbability] move options for 'likely' and 'unlikely'

[Sanjay Patel via cfe-commits]

Author: Sanjay Patel
Date: 2021-03-20T14:46:46-04:00
New Revision: ee8b53815ddf6f6f94ade0068903cd5ae843fafa

URL: https://github.com/llvm/llvm-project/commit/ee8b53815ddf6f6f94ade0068903cd5ae843fafa
DIFF: https://github.com/llvm/llvm-project/commit/ee8b53815ddf6f6f94ade0068903cd5ae843fafa.diff

LOG: [BranchProbability] move options for 'likely' and 'unlikely'

This makes the settings available for use in other passes by housing
them within the Support lib, but NFC otherwise.

See D98898 for the proposed usage in SimplifyCFG
(where this change was originally included).

Differential Revision: https://reviews.llvm.org/D98945

Added: 
    

Modified: 
    clang/lib/CodeGen/CodeGenFunction.cpp
    llvm/include/llvm/Support/BranchProbability.h
    llvm/include/llvm/Transforms/Scalar/LowerExpectIntrinsic.h
    llvm/lib/Support/BranchProbability.cpp
    llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp

Removed: 
    


################################################################################
diff  --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index a00ae74fa165..18927b46958c 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -42,8 +42,8 @@
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/Operator.h"
+#include "llvm/Support/BranchProbability.h"
 #include "llvm/Support/CRC.h"
-#include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
 using namespace clang;
 using namespace CodeGen;

diff  --git a/llvm/include/llvm/Support/BranchProbability.h b/llvm/include/llvm/Support/BranchProbability.h
index 6c7ad1fe2a52..f977c70221a5 100644
--- a/llvm/include/llvm/Support/BranchProbability.h
+++ b/llvm/include/llvm/Support/BranchProbability.h
@@ -13,6 +13,7 @@
 #ifndef LLVM_SUPPORT_BRANCHPROBABILITY_H
 #define LLVM_SUPPORT_BRANCHPROBABILITY_H
 
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Support/DataTypes.h"
 #include <algorithm>
 #include <cassert>
@@ -21,6 +22,9 @@
 
 namespace llvm {
 
+extern cl::opt<uint32_t> LikelyBranchWeight;
+extern cl::opt<uint32_t> UnlikelyBranchWeight;
+
 class raw_ostream;
 
 // This class represents Branch Probability as a non-negative fraction that is

diff  --git a/llvm/include/llvm/Transforms/Scalar/LowerExpectIntrinsic.h b/llvm/include/llvm/Transforms/Scalar/LowerExpectIntrinsic.h
index 22b2e649e4d4..4e47ff70d557 100644
--- a/llvm/include/llvm/Transforms/Scalar/LowerExpectIntrinsic.h
+++ b/llvm/include/llvm/Transforms/Scalar/LowerExpectIntrinsic.h
@@ -17,7 +17,6 @@
 
 #include "llvm/IR/Function.h"
 #include "llvm/IR/PassManager.h"
-#include "llvm/Support/CommandLine.h"
 
 namespace llvm {
 
@@ -32,8 +31,6 @@ struct LowerExpectIntrinsicPass : PassInfoMixin<LowerExpectIntrinsicPass> {
   PreservedAnalyses run(Function &F, FunctionAnalysisManager &);
 };
 
-extern cl::opt<uint32_t> LikelyBranchWeight;
-extern cl::opt<uint32_t> UnlikelyBranchWeight;
 }
 
 #endif

diff  --git a/llvm/lib/Support/BranchProbability.cpp b/llvm/lib/Support/BranchProbability.cpp
index 60d5478a9052..d93d9cffb9f7 100644
--- a/llvm/lib/Support/BranchProbability.cpp
+++ b/llvm/lib/Support/BranchProbability.cpp
@@ -19,6 +19,20 @@
 
 using namespace llvm;
 
+// These default values are chosen to represent an extremely skewed outcome for
+// a condition, but they leave some room for interpretation by later passes.
+//
+// If the documentation for __builtin_expect() was made explicit that it should
+// only be used in extreme cases, we could make this ratio higher. As it stands,
+// programmers may be using __builtin_expect() / llvm.expect to annotate that a
+// branch is only mildly likely or unlikely to be taken.
+cl::opt<uint32_t> llvm::LikelyBranchWeight(
+    "likely-branch-weight", cl::Hidden, cl::init(2000),
+    cl::desc("Weight of the branch likely to be taken (default = 2000)"));
+cl::opt<uint32_t> llvm::UnlikelyBranchWeight(
+    "unlikely-branch-weight", cl::Hidden, cl::init(1),
+    cl::desc("Weight of the branch unlikely to be taken (default = 1)"));
+
 constexpr uint32_t BranchProbability::D;
 
 raw_ostream &BranchProbability::print(raw_ostream &OS) const {

diff  --git a/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp b/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
index da13075dfee2..d862fcfe8ce5 100644
--- a/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
+++ b/llvm/lib/Transforms/Scalar/LowerExpectIntrinsic.cpp
@@ -24,6 +24,7 @@
 #include "llvm/IR/Metadata.h"
 #include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
+#include "llvm/Support/BranchProbability.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Transforms/Scalar.h"
 
@@ -34,25 +35,6 @@ using namespace llvm;
 STATISTIC(ExpectIntrinsicsHandled,
           "Number of 'expect' intrinsic instructions handled");
 
-// These default values are chosen to represent an extremely skewed outcome for
-// a condition, but they leave some room for interpretation by later passes.
-//
-// If the documentation for __builtin_expect() was made explicit that it should
-// only be used in extreme cases, we could make this ratio higher. As it stands,
-// programmers may be using __builtin_expect() / llvm.expect to annotate that a
-// branch is likely or unlikely to be taken.
-//
-// There is a known dependency on this ratio in CodeGenPrepare when transforming
-// 'select' instructions. It may be worthwhile to hoist these values to some
-// shared space, so they can be used directly by other passes.
-
-cl::opt<uint32_t> llvm::LikelyBranchWeight(
-    "likely-branch-weight", cl::Hidden, cl::init(2000),
-    cl::desc("Weight of the branch likely to be taken (default = 2000)"));
-cl::opt<uint32_t> llvm::UnlikelyBranchWeight(
-    "unlikely-branch-weight", cl::Hidden, cl::init(1),
-    cl::desc("Weight of the branch unlikely to be taken (default = 1)"));
-
 static std::tuple<uint32_t, uint32_t>
 getBranchWeight(Intrinsic::ID IntrinsicID, CallInst *CI, int BranchCount) {
   if (IntrinsicID == Intrinsic::expect) {