8 files changed, 82 insertions, 24 deletions
diff --git a/llvm/include/llvm/InitializePasses.h b/llvm/include/llvm/InitializePasses.h
index 7e572232d5b..92127fa3301 100644
--- a/llvm/include/llvm/InitializePasses.h
+++ b/llvm/include/llvm/InitializePasses.h
@@ -260,7 +260,7 @@ void initializeStackColoringPass(PassRegistry&);
 void initializeStackSlotColoringPass(PassRegistry&);
 void initializeStraightLineStrengthReducePass(PassRegistry &);
 void initializeStripDeadDebugInfoPass(PassRegistry&);
-void initializeStripDeadPrototypesPassPass(PassRegistry&);
+void initializeStripDeadPrototypesLegacyPassPass(PassRegistry&);
 void initializeStripDebugDeclarePass(PassRegistry&);
 void initializeStripNonDebugSymbolsPass(PassRegistry&);
 void initializeStripSymbolsPass(PassRegistry&);
diff --git a/llvm/include/llvm/Transforms/IPO/StripDeadPrototypes.h b/llvm/include/llvm/Transforms/IPO/StripDeadPrototypes.h
new file mode 100644
index 00000000000..9dddd12871c
--- /dev/null
+++ b/llvm/include/llvm/Transforms/IPO/StripDeadPrototypes.h
@@ -0,0 +1,34 @@
+//===-- StripDeadPrototypes.h - Remove unused function declarations -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass loops over all of the functions in the input module, looking for
+// dead declarations and removes them. Dead declarations are declarations of
+// functions for which no implementation is available (i.e., declarations for
+// unused library functions).
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_IPO_STRIPDEADPROTOTYPES_H
+#define LLVM_TRANSFORMS_IPO_STRIPDEADPROTOTYPES_H
+
+#include "llvm/IR/Module.h"
+#include "llvm/IR/PassManager.h"
+
+namespace llvm {
+
+/// Pass to remove unused function declarations.
+class StripDeadPrototypesPass {
+public:
+  static StringRef name() { return "StripDeadPrototypesPass"; }
+  PreservedAnalyses run(Module &M);
+};
+
+}
+
+#endif // LLVM_TRANSFORMS_IPO_STRIPDEADPROTOTYPES_H
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
index f18fcb18575..b24c615f85f 100644
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -30,6 +30,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Transforms/InstCombine/InstCombine.h"
+#include "llvm/Transforms/IPO/StripDeadPrototypes.h"
 #include "llvm/Transforms/Scalar/ADCE.h"
 #include "llvm/Transforms/Scalar/EarlyCSE.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
index 6f523301f92..638f606c402 100644
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -31,6 +31,7 @@ MODULE_PASS("invalidate<all>", InvalidateAllAnalysesPass())
 MODULE_PASS("no-op-module", NoOpModulePass())
 MODULE_PASS("print", PrintModulePass(dbgs()))
 MODULE_PASS("print-cg", LazyCallGraphPrinterPass(dbgs()))
+MODULE_PASS("strip-dead-prototypes", StripDeadPrototypesPass())
 MODULE_PASS("verify", VerifierPass())
 #undef MODULE_PASS
 
diff --git a/llvm/lib/Transforms/IPO/IPO.cpp b/llvm/lib/Transforms/IPO/IPO.cpp
index 7ecc37710ed..97e45843682 100644
--- a/llvm/lib/Transforms/IPO/IPO.cpp
+++ b/llvm/lib/Transforms/IPO/IPO.cpp
@@ -40,7 +40,7 @@ void llvm::initializeIPO(PassRegistry &Registry) {
   initializeMergeFunctionsPass(Registry);
   initializePartialInlinerPass(Registry);
   initializePruneEHPass(Registry);
-  initializeStripDeadPrototypesPassPass(Registry);
+  initializeStripDeadPrototypesLegacyPassPass(Registry);
   initializeStripSymbolsPass(Registry);
   initializeStripDebugDeclarePass(Registry);
   initializeStripDeadDebugInfoPass(Registry);
diff --git a/llvm/lib/Transforms/IPO/StripDeadPrototypes.cpp b/llvm/lib/Transforms/IPO/StripDeadPrototypes.cpp
index 22ba1c6c674..c94cc7c74a8 100644
--- a/llvm/lib/Transforms/IPO/StripDeadPrototypes.cpp
+++ b/llvm/lib/Transforms/IPO/StripDeadPrototypes.cpp
@@ -14,35 +14,19 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/IPO/StripDeadPrototypes.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Pass.h"
+#include "llvm/Transforms/IPO.h"
+
 using namespace llvm;
 
 #define DEBUG_TYPE "strip-dead-prototypes"
 
 STATISTIC(NumDeadPrototypes, "Number of dead prototypes removed");
 
-namespace {
-
-/// @brief Pass to remove unused function declarations.
-class StripDeadPrototypesPass : public ModulePass {
-public:
-  static char ID; // Pass identification, replacement for typeid
-  StripDeadPrototypesPass() : ModulePass(ID) {
-    initializeStripDeadPrototypesPassPass(*PassRegistry::getPassRegistry());
-  }
-  bool runOnModule(Module &M) override;
-};
-
-} // end anonymous namespace
-
-char StripDeadPrototypesPass::ID = 0;
-INITIALIZE_PASS(StripDeadPrototypesPass, "strip-dead-prototypes",
-                "Strip Unused Function Prototypes", false, false)
-
-bool StripDeadPrototypesPass::runOnModule(Module &M) {
+static bool stripDeadPrototypes(Module &M) {
   bool MadeChange = false;
 
   // Erase dead function prototypes.
@@ -69,6 +53,32 @@ bool StripDeadPrototypesPass::runOnModule(Module &M) {
   return MadeChange;
 }
 
+PreservedAnalyses StripDeadPrototypesPass::run(Module &M) {
+  if (stripDeadPrototypes(M))
+    return PreservedAnalyses::none();
+  return PreservedAnalyses::all();
+}
+
+namespace {
+
+class StripDeadPrototypesLegacyPass : public ModulePass {
+public:
+  static char ID; // Pass identification, replacement for typeid
+  StripDeadPrototypesLegacyPass() : ModulePass(ID) {
+    initializeStripDeadPrototypesLegacyPassPass(
+        *PassRegistry::getPassRegistry());
+  }
+  bool runOnModule(Module &M) override {
+    return stripDeadPrototypes(M);
+  }
+};
+
+} // end anonymous namespace
+
+char StripDeadPrototypesLegacyPass::ID = 0;
+INITIALIZE_PASS(StripDeadPrototypesLegacyPass, "strip-dead-prototypes",
+                "Strip Unused Function Prototypes", false, false)
+
 ModulePass *llvm::createStripDeadPrototypesPass() {
-  return new StripDeadPrototypesPass();
+  return new StripDeadPrototypesLegacyPass();
 }
diff --git a/llvm/test/Transforms/LowerExpectIntrinsic/basic.ll b/llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
index 73d9f44ee7e..69e67cd7c1d 100644
--- a/llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
+++ b/llvm/test/Transforms/LowerExpectIntrinsic/basic.ll
@@ -1,5 +1,5 @@
 ; RUN: opt -lower-expect -strip-dead-prototypes -S -o - < %s | FileCheck %s
-; RUN: opt -S -passes=lower-expect < %s | opt -strip-dead-prototypes -S | FileCheck %s
+; RUN: opt -S -passes='function(lower-expect),strip-dead-prototypes' < %s | FileCheck %s
 
 ; CHECK-LABEL: @test1(
 define i32 @test1(i32 %x) nounwind uwtable ssp {
diff --git a/llvm/test/Transforms/StripDeadPrototypes/basic.ll b/llvm/test/Transforms/StripDeadPrototypes/basic.ll
new file mode 100644
index 00000000000..6845faf7d03
--- /dev/null
+++ b/llvm/test/Transforms/StripDeadPrototypes/basic.ll
@@ -0,0 +1,12 @@
+; RUN: opt -strip-dead-prototypes -S -o - < %s | FileCheck %s
+; RUN: opt -S -passes=strip-dead-prototypes < %s | FileCheck %s
+
+; CHECK: declare i32 @f
+declare i32 @f()
+; CHECK-NOT: declare i32 @g
+declare i32 @g()
+
+define i32 @foo() {
+  %call = call i32 @f()
+  ret i32 %call
+}