PGO: Add IR-based PGO.

driver/cl_options_instrumentation.cpp

@@ -15,9 +15,11 @@
 
 #include "driver/cl_options_instrumentation.h"
 
+#include "errors.h"
 #include "globals.h"
 
 namespace {
+namespace cl = llvm::cl;
 
 #if LDC_LLVM_VER >= 309
 /// Option for generating IR-based PGO instrumentation (LLVM pass)
@@ -82,6 +84,29 @@ void initializeInstrumentationOptionsFromCmdline() {
     pgoMode = PGO_ASTBasedUse;
     initFromPathString(global.params.datafileInstrProf, ASTPGOInstrUseFile);
   }
+#if LDC_LLVM_VER >= 309
+  else if (IRPGOInstrGenFile.getNumOccurrences() > 0) {
+    pgoMode = PGO_IRBasedInstr;
+    if (IRPGOInstrGenFile.empty()) {
+      global.params.datafileInstrProf = "default_%m.profraw";
+    } else {
+      initFromPathString(global.params.datafileInstrProf, IRPGOInstrGenFile);
+    }
+  } else if (!IRPGOInstrUseFile.empty()) {
+    pgoMode = PGO_IRBasedUse;
+    initFromPathString(global.params.datafileInstrProf, IRPGOInstrUseFile);
+  }
+#endif
+
+  // There is a bug in (our use of?) LLVM where codegen errors with
+  // PGO_IRBasedInstr for Windows targets. So disable IRBased PGO on Windows for
+  // now.
+  assert(global.params.targetTriple);
+  if ((pgoMode == PGO_IRBasedInstr) &&
+      global.params.targetTriple->isOSWindows()) {
+    error(Loc(),
+          "'-fprofile-generate' is not yet supported for Windows targets.");
+  }
 
   if (dmdFunctionTrace)
     global.params.trace = true;

driver/cl_options_instrumentation.h

@@ -24,7 +24,8 @@ namespace cl = llvm::cl;
 extern cl::opt<bool> instrumentFunctions;
 
 /// This initializes the instrumentation options, and checks the validity of the
-/// commandline flags. It should be called only once.
+/// commandline flags. targetTriple should be initialized before calling this.
+/// It should be called only once.
 void initializeInstrumentationOptionsFromCmdline();
 
 enum PGOKind {

driver/main.cpp

@@ -431,7 +431,6 @@ void parseCommandLine(int argc, char **argv, Strings &sourceFiles,
   }
 #endif
 
-  opts::initializeInstrumentationOptionsFromCmdline();
   opts::initializeSanitizerOptionsFromCmdline();
 
   processVersions(debugArgs, "debug", DebugCondition::setGlobalLevel,
@@ -1067,6 +1066,8 @@ int cppmain(int argc, char **argv) {
     global.lib_ext = "a";
   }
 
+  opts::initializeInstrumentationOptionsFromCmdline();
+
   Strings libmodules;
   return mars_mainBody(files, libmodules);
 }

gen/optimizer.cpp

@@ -207,7 +207,8 @@ static void addSanitizerCoveragePass(const PassManagerBuilder &Builder,
 }
 
 // Adds PGO instrumentation generation and use passes.
-static void addPGOPasses(legacy::PassManagerBase &mpm, unsigned optLevel) {
+static void addPGOPasses(PassManagerBuilder &builder,
+                         legacy::PassManagerBase &mpm, unsigned optLevel) {
   if (opts::isInstrumentingForASTBasedPGO()) {
     InstrProfOptions options;
     options.NoRedZone = global.params.disableRedZone;
@@ -227,6 +228,16 @@ static void addPGOPasses(legacy::PassManagerBase &mpm, unsigned optLevel) {
     }
 #endif
   }
+#if LDC_LLVM_VER >= 309
+  else if (opts::isInstrumentingForIRBasedPGO()) {
+#if LDC_LLVM_VER >= 400
+    builder.EnablePGOInstrGen = true;
+#endif
+    builder.PGOInstrGen = global.params.datafileInstrProf;
+  } else if (opts::isUsingIRBasedPGOProfile()) {
+    builder.PGOInstrUse = global.params.datafileInstrProf;
+  }
+#endif
 }
 
 /**
@@ -328,7 +339,7 @@ static void addOptimizationPasses(legacy::PassManagerBase &mpm,
   builder.addExtension(PassManagerBuilder::EP_OptimizerLast,
                        addStripExternalsPass);
 
-  addPGOPasses(mpm, optLevel);
+  addPGOPasses(builder, mpm, optLevel);
 
   builder.populateFunctionPassManager(fpm);
   builder.populateModulePassManager(mpm);

tests/PGO/irbased_indirect_calls.d

@@ -0,0 +1,62 @@
+// Test instrumentation of indirect calls
+
+// REQUIRES: atleast_llvm309
+
+// There is an LLVM bug, this test currently errors during LLVM codegen for Windows.
+// XFAIL: Windows
+
+// RUN: %ldc -O3 -fprofile-generate=%t.profraw -run %s  \
+// RUN:   &&  %profdata merge %t.profraw -o %t.profdata \
+// RUN:   &&  %ldc -O3 -c -output-ll -of=%t.use.ll -fprofile-use=%t.profdata %s \
+// RUN:   &&  FileCheck %s -check-prefix=PROFUSE < %t.use.ll
+
+import ldc.attributes : weak;
+
+extern (C)
+{ // simplify name mangling for simpler string matching
+
+    @weak // disable reasoning about this function
+    void hot()
+    {
+    }
+
+    void luke()
+    {
+    }
+
+    void cold()
+    {
+    }
+
+    void function() foo;
+
+    @weak // disable reasoning about this function
+    void select_func(int i)
+    {
+        if (i < 1700)
+            foo = &hot;
+        else if (i < 1990)
+            foo = &luke;
+        else
+            foo = &cold;
+    }
+
+} // extern C
+
+// PROFUSE-LABEL: @_Dmain(
+int main()
+{
+    for (int i; i < 2000; ++i)
+    {
+        select_func(i);
+
+        // PROFUSE:  [[REG1:%[0-9]+]] = load void ()*, void ()** @foo
+        // PROFUSE:  [[REG2:%[0-9]+]] = icmp eq void ()* [[REG1]], @hot
+        // PROFUSE:  call void @hot()
+        // PROFUSE:  call void [[REG1]]()
+
+        foo();
+    }
+
+    return 0;
+}