From 476bfb7a1043f5aa07e23bef9188542b9bea3bd1 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Wed, 29 Sep 2010 23:52:12 +0000
Subject: [PATCH] Add strpbrk folding to SimplifyLibCalls.

llvm-svn: 115111
---
 lib/Transforms/Scalar/SimplifyLibCalls.cpp  | 49 ++++++++++++++++++---
 test/Transforms/SimplifyLibCalls/StrPBrk.ll | 25 +++++++++++
 2 files changed, 67 insertions(+), 7 deletions(-)
 create mode 100644 test/Transforms/SimplifyLibCalls/StrPBrk.ll

diff --git a/lib/Transforms/Scalar/SimplifyLibCalls.cpp b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
index 75754a55854..c4787c82f53 100644
--- a/lib/Transforms/Scalar/SimplifyLibCalls.cpp
+++ b/lib/Transforms/Scalar/SimplifyLibCalls.cpp
@@ -522,6 +522,46 @@ struct StrLenOpt : public LibCallOptimization {
   }
 };
 
+
+//===---------------------------------------===//
+// 'strpbrk' Optimizations
+
+struct StrPBrkOpt : public LibCallOptimization {
+  virtual Value *CallOptimizer(Function *Callee, CallInst *CI, IRBuilder<> &B) {
+    const FunctionType *FT = Callee->getFunctionType();
+    if (FT->getNumParams() != 2 ||
+        FT->getParamType(0) != Type::getInt8PtrTy(*Context) ||
+        FT->getParamType(1) != FT->getParamType(0) ||
+        FT->getReturnType() != FT->getParamType(0))
+      return 0;
+
+    std::string S1, S2;
+    bool HasS1 = GetConstantStringInfo(CI->getArgOperand(0), S1);
+    bool HasS2 = GetConstantStringInfo(CI->getArgOperand(1), S2);
+
+    // strpbrk(s, "") -> NULL
+    // strpbrk("", s) -> NULL
+    if ((HasS1 && S1.empty()) || (HasS2 && S2.empty()))
+      return Constant::getNullValue(CI->getType());
+
+    // Constant folding.
+    if (HasS1 && HasS2) {
+      size_t I = S1.find_first_of(S2);
+      if (I == std::string::npos) // No match.
+        return Constant::getNullValue(CI->getType());
+
+      Value *Idx = ConstantInt::get(Type::getInt64Ty(*Context), I);
+      return B.CreateGEP(CI->getArgOperand(0), Idx, "strpbrk");
+    }
+
+    // strpbrk(s, "a") -> strchr(s, 'a')
+    if (TD && HasS2 && S2.size() == 1)
+      return EmitStrChr(CI->getArgOperand(0), S2[0], B, TD);
+
+    return 0;
+  }
+};
+
 //===---------------------------------------===//
 // 'strto*' Optimizations.  This handles strtol, strtod, strtof, strtoul, etc.
 
@@ -1256,7 +1296,7 @@ namespace {
     // String and Memory LibCall Optimizations
     StrCatOpt StrCat; StrNCatOpt StrNCat; StrChrOpt StrChr; StrRChrOpt StrRChr;
     StrCmpOpt StrCmp; StrNCmpOpt StrNCmp; StrCpyOpt StrCpy; StrCpyOpt StrCpyChk;
-    StrNCpyOpt StrNCpy; StrLenOpt StrLen;
+    StrNCpyOpt StrNCpy; StrLenOpt StrLen; StrPBrkOpt StrPBrk;
     StrToOpt StrTo; StrStrOpt StrStr;
     MemCmpOpt MemCmp; MemCpyOpt MemCpy; MemMoveOpt MemMove; MemSetOpt MemSet;
     // Math Library Optimizations
@@ -1309,6 +1349,7 @@ void SimplifyLibCalls::InitOptimizations() {
   Optimizations["strcpy"] = &StrCpy;
   Optimizations["strncpy"] = &StrNCpy;
   Optimizations["strlen"] = &StrLen;
+  Optimizations["strpbrk"] = &StrPBrk;
   Optimizations["strtol"] = &StrTo;
   Optimizations["strtod"] = &StrTo;
   Optimizations["strtof"] = &StrTo;
@@ -2209,12 +2250,6 @@ bool SimplifyLibCalls::doInitialization(Module &M) {
 //   * stpcpy(str, "literal") ->
 //           llvm.memcpy(str,"literal",strlen("literal")+1,1)
 //
-// strpbrk:
-//   * strpbrk(s,a) -> offset_in_for(s,a)
-//      (if s and a are both constant strings)
-//   * strpbrk(s,"") -> 0
-//   * strpbrk(s,a) -> strchr(s,a[0]) (if a is constant string of length 1)
-//
 // strspn, strcspn:
 //   * strspn(s,a)   -> const_int (if both args are constant)
 //   * strspn("",a)  -> 0
diff --git a/test/Transforms/SimplifyLibCalls/StrPBrk.ll b/test/Transforms/SimplifyLibCalls/StrPBrk.ll
new file mode 100644
index 00000000000..29c3b7477b4
--- /dev/null
+++ b/test/Transforms/SimplifyLibCalls/StrPBrk.ll
@@ -0,0 +1,25 @@
+; RUN: opt < %s -simplify-libcalls -S | FileCheck %s
+
+target datalayout = "-p:64:64:64"
+
+@hello = constant [12 x i8] c"hello world\00"
+@w = constant [2 x i8] c"w\00"
+@null = constant [1 x i8] zeroinitializer
+
+declare i8* @strpbrk(i8*, i8*)
+
+define void @test(i8* %s1, i8* %s2) {
+	%hello_p = getelementptr [12 x i8]* @hello, i32 0, i32 0
+	%w_p = getelementptr [2 x i8]* @w, i32 0, i32 0
+	%null_p = getelementptr [1 x i8]* @null, i32 0, i32 0
+	%test1 = call i8* @strpbrk(i8* %null_p, i8* %s2)
+	%test2 = call i8* @strpbrk(i8* %s1, i8* %null_p)
+; CHECK-NOT: call i8* @strpbrk
+	%test3 = call i8* @strpbrk(i8* %s1, i8* %w_p)
+; CHECK: call i8* @strchr(i8* %s1, i32 119)
+	%test4 = call i8* @strpbrk(i8* %hello_p, i8* %w_p)
+; CHECK: getelementptr i8* %hello_p, i64 6
+	%test5 = call i8* @strpbrk(i8* %s1, i8* %s2)
+; CHECK: call i8* @strpbrk(i8* %s1, i8* %s2)
+	ret void
+}