#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Allocator.h"
+#include "llvm/Support/CommandLine.h"
#include "llvm/Target/TargetLibraryInfo.h"
#include "llvm/Transforms/Utils/BuildLibCalls.h"
using namespace llvm;
+static cl::opt<bool>
+ColdErrorCalls("error-reporting-is-cold", cl::init(true),
+ cl::Hidden, cl::desc("Treat error-reporting calls as cold"));
+
/// This class is the abstract base class for the set of optimizations that
/// corresponds to one library call.
namespace {
// Formatting and IO Library Call Optimizations
//===----------------------------------------------------------------------===//
+struct ErrorReportingOpt : public LibCallOptimization {
+ ErrorReportingOpt(int S = -1) : StreamArg(S) {}
+
+ virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &) {
+ // Error reporting calls should be cold, mark them as such.
+ // This applies even to non-builtin calls: it is only a hint and applies to
+ // functions that the frontend might not understand as builtins.
+
+ // This heuristic was suggested in:
+ // Improving Static Branch Prediction in a Compiler
+ // Brian L. Deitrich, Ben-Chung Cheng, Wen-mei W. Hwu
+ // Proceedings of PACT'98, Oct. 1998, IEEE
+
+ if (!CI->hasFnAttr(Attribute::Cold) && isReportingError(Callee, CI)) {
+ CI->addAttribute(AttributeSet::FunctionIndex, Attribute::Cold);
+ }
+
+ return 0;
+ }
+
+protected:
+ bool isReportingError(Function *Callee, CallInst *CI) {
+ if (!ColdErrorCalls)
+ return false;
+
+ if (!Callee || !Callee->isDeclaration())
+ return false;
+
+ if (StreamArg < 0)
+ return true;
+
+ // These functions might be considered cold, but only if their stream
+ // argument is stderr.
+
+ if (StreamArg >= (int) CI->getNumArgOperands())
+ return false;
+ LoadInst *LI = dyn_cast<LoadInst>(CI->getArgOperand(StreamArg));
+ if (!LI)
+ return false;
+ GlobalVariable *GV = dyn_cast<GlobalVariable>(LI->getPointerOperand());
+ if (!GV || !GV->isDeclaration())
+ return false;
+ return GV->getName() == "stderr";
+ }
+
+ int StreamArg;
+};
+
struct PrintFOpt : public LibCallOptimization {
Value *optimizeFixedFormatString(Function *Callee, CallInst *CI,
IRBuilder<> &B) {
struct FPrintFOpt : public LibCallOptimization {
Value *optimizeFixedFormatString(Function *Callee, CallInst *CI,
IRBuilder<> &B) {
+ ErrorReportingOpt ER(/* StreamArg = */ 0);
+ (void) ER.callOptimizer(Callee, CI, B);
+
// All the optimizations depend on the format string.
StringRef FormatStr;
if (!getConstantStringInfo(CI->getArgOperand(1), FormatStr))
struct FWriteOpt : public LibCallOptimization {
virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+ ErrorReportingOpt ER(/* StreamArg = */ 3);
+ (void) ER.callOptimizer(Callee, CI, B);
+
// Require a pointer, an integer, an integer, a pointer, returning integer.
FunctionType *FT = Callee->getFunctionType();
if (FT->getNumParams() != 4 || !FT->getParamType(0)->isPointerTy() ||
struct FPutsOpt : public LibCallOptimization {
virtual Value *callOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+ ErrorReportingOpt ER(/* StreamArg = */ 1);
+ (void) ER.callOptimizer(Callee, CI, B);
+
// These optimizations require DataLayout.
if (!TD) return 0;
static ToAsciiOpt ToAscii;
// Formatting and IO library call optimizations.
+static ErrorReportingOpt ErrorReporting;
+static ErrorReportingOpt ErrorReporting0(0);
+static ErrorReportingOpt ErrorReporting1(1);
static PrintFOpt PrintF;
static SPrintFOpt SPrintF;
static FPrintFOpt FPrintF;
return &FPuts;
case LibFunc::puts:
return &Puts;
+ case LibFunc::perror:
+ return &ErrorReporting;
+ case LibFunc::vfprintf:
+ case LibFunc::fiprintf:
+ return &ErrorReporting0;
+ case LibFunc::fputc:
+ return &ErrorReporting1;
case LibFunc::ceil:
case LibFunc::fabs:
case LibFunc::floor:
--- /dev/null
+; Test the static branch probability heuristics for error-reporting functions.
+; RUN: opt < %s -instcombine -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+%struct._IO_FILE = type { i32, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, i8*, %struct._IO_marker*, %struct._IO_FILE*, i32, i32, i64, i16, i8, [1 x i8], i8*, i64, i8*, i8*, i8*, i8*, i64, i32, [20 x i8] }
+%struct._IO_marker = type { %struct._IO_marker*, %struct._IO_FILE*, i32 }
+
+@stdout = external global %struct._IO_FILE*
+@stderr = external global %struct._IO_FILE*
+@.str = private unnamed_addr constant [13 x i8] c"an error: %d\00", align 1
+@.str1 = private unnamed_addr constant [9 x i8] c"an error\00", align 1
+
+define i32 @test1(i32 %a) #0 {
+; CHECK-LABEL: @test1
+entry:
+ %cmp = icmp sgt i32 %a, 8
+ br i1 %cmp, label %if.then, label %return
+
+if.then: ; preds = %entry
+ %0 = load %struct._IO_FILE** @stderr, align 8
+ %call = tail call i32 (%struct._IO_FILE*, i8*, ...)* @fprintf(%struct._IO_FILE* %0, i8* getelementptr inbounds ([13 x i8]* @.str, i64 0, i64 0), i32 %a) #1
+ br label %return
+
+; CHECK: %call = tail call i32 (%struct._IO_FILE*, i8*, ...)* @fprintf(%struct._IO_FILE* %0, i8* getelementptr inbounds ([13 x i8]* @.str, i64 0, i64 0), i32 %a) #[[AT1:[0-9]+]]
+
+return: ; preds = %entry, %if.then
+ %retval.0 = phi i32 [ 1, %if.then ], [ 0, %entry ]
+ ret i32 %retval.0
+}
+
+declare i32 @fprintf(%struct._IO_FILE* nocapture, i8* nocapture readonly, ...) #1
+
+define i32 @test2(i32 %a) #0 {
+; CHECK-LABEL: @test2
+entry:
+ %cmp = icmp sgt i32 %a, 8
+ br i1 %cmp, label %if.then, label %return
+
+if.then: ; preds = %entry
+ %0 = load %struct._IO_FILE** @stderr, align 8
+ %1 = tail call i64 @fwrite(i8* getelementptr inbounds ([9 x i8]* @.str1, i64 0, i64 0), i64 8, i64 1, %struct._IO_FILE* %0)
+ br label %return
+
+; CHECK: tail call i64 @fwrite(i8* getelementptr inbounds ([9 x i8]* @.str1, i64 0, i64 0), i64 8, i64 1, %struct._IO_FILE* %0) #[[AT2:[0-9]+]]
+
+return: ; preds = %entry, %if.then
+ %retval.0 = phi i32 [ 1, %if.then ], [ 0, %entry ]
+ ret i32 %retval.0
+}
+
+declare i64 @fwrite(i8* nocapture, i64, i64, %struct._IO_FILE* nocapture) #1
+
+define i32 @test3(i32 %a) #0 {
+; CHECK-LABEL: @test3
+entry:
+ %cmp = icmp sgt i32 %a, 8
+ br i1 %cmp, label %if.then, label %return
+
+if.then: ; preds = %entry
+ %0 = load %struct._IO_FILE** @stdout, align 8
+ %1 = tail call i64 @fwrite(i8* getelementptr inbounds ([9 x i8]* @.str1, i64 0, i64 0), i64 8, i64 1, %struct._IO_FILE* %0)
+ br label %return
+
+; CHECK-NOT: tail call i64 @fwrite(i8* getelementptr inbounds ([9 x i8]* @.str1, i64 0, i64 0), i64 8, i64 1, %struct._IO_FILE* %0) #[[AT2]]
+
+return: ; preds = %entry, %if.then
+ %retval.0 = phi i32 [ 1, %if.then ], [ 0, %entry ]
+ ret i32 %retval.0
+}
+
+attributes #0 = { nounwind uwtable }
+attributes #1 = { nounwind }
+
+; CHECK: attributes #[[AT1]] = { cold nounwind }
+; CHECK: attributes #[[AT2]] = { cold }
+